Sign up to save your podcasts
Or
Share Show 1397: The Surprising Secrets of Sunlight’s Health Benefits (Archive)
Share to email
Share to Facebook
Share to X
Share to email
Share to Facebook
Share to X
Or
Show 1397: The Surprising Secrets of Sunlight’s Health Benefits (Archive)
In this episode, our guest is a dermatologist who wants us to consider sunlight’s health benefits. That is a minority opinion among dermatologists. Dr. Richard Weller tells us why vitamin D is overrated and not the most important aspect of sun exposure.
At The People’s Pharmacy, we bring you the latest research-backed insights on health, even when they challenge established views. In this episode, Dr. Richard Weller highlights how moderate sunlight may offer unexpected health benefits while placing melanoma risk in context. This content is provided for informational and educational purposes only. Always consult a qualified healthcare provider before making changes to your sun exposure habits or medical care.
You could listen through your local public radio station or get the live stream at 7 am EDT on your computer or smart phone (wunc.org). Here is a link so you can find which stations carry our broadcast. If you can’t listen to the broadcast, you may wish to hear the podcast later. You can subscribe through your favorite podcast provider, download the mp3 using the link at the bottom of the page, or listen to the stream on this post starting on Sept. 1, 2025.
The Secrets of Sunlight’s Health Benefits:
Dermatologists generally advise us to stay out of the sun as much as possible. After all, excessive sun exposure causes skin aging and skin cancer, conditions for which people frequently consult them. However, even if we could all live inside, wear protective clothing and high SPF sunscreen whenever we ventured out, would that be wise?
According to our guest, Dr. Richard Weller, and his colleagues, “insufficient sun exposure has become a real public health problem” (International Journal of Environmental Research and Public Health, July 13, 2020). While this problem is more acute in Europe than the US, they still estimate that more than 300,000 Americans die each year due to inadequate sun on their skin. What is going on?
How Does Sunlight Affect Skin?
For decades, we have heard that the principal effect of sunlight on skin is the production of vitamin D. Therefore, the dermatologists have concluded, rather than take the risk of exposing skin to sunshine, why not just swallow vitamin D supplements?
The problem with that proposal is that it hasn’t worked very well. Many studies show that people with low levels of circulating vitamin D are more vulnerable to high blood pressure, atrial fibrillation, heart disease, diabetes and infections, among other problems.
However, people who take vitamin D supplements don’t always get the expected benefits. Perhaps vitamin D is a marker for sun exposure rather than the most important outcome.
Human Evolution and Skin Color:
Humans evolved in Africa, where dark skin is an advantage, offering protection from the most harmful effects of ultraviolet radiation. By about 60,000 years ago, people were migrating to other parts of the world. Yet analyses suggest that although they arrived in Europe by about 40,000 years ago, genes for pale skin didn’t become common until less than 10,000 years ago.
Anthropologists have hypothesized that pale skin is an adaptation to inadequate sunlight in northern regions. Because vitamin D is a well-recognized consequence of sunlight on skin, they have assumed that was the driver. Dr. Weller suggests that nitric oxide was (and still is) more important. He notes that the evolution of pale skin happens around the same time that people begin to cluster together in farming communities, where they are more likely to be exposed to infectious diseases.
Is Nitric Oxide the Source of Sunlight’s Health Benefits?
In 1996, Dr. Weller was the first scientist to find that human skin creates a compound called nitric oxide (NO) under sunlight. This compound is then absorbed into the skin, where it helps relax blood vessels and lower blood pressure. Here is a link to his TED talk on the topic.
This is where Dr. Weller’s approach differs from that of more conventional dermatologists. With proper caveats that the US is at much lower latitudes, in general, than most of Europe, he proposes that more sunlight, not less, could lower mortality rates. (Lower latitudes get more sunshine.) His analysis was just published in the prestigious Journal of Investigative Dermatology (August 2024).
The data underpinning this claim are from an analysis of the UK Biobank, a remarkable treasure trove of information. Dr. Weller and his colleagues have found that in the UK, people who get more sunlight are less likely to die within a specified time frame. We call that lower all-cause mortality.
You can read the research report here (Health & Place, Sept. 2024). It was discussed in this article in The Economist (Aug. 12, 2024).
This Week’s Guest:
Richard Weller, MD, FRCP(Ed), is Professor of Medical Dermatology at the University of Edinburgh. He holds the Personal Chair of Medical Dermatology in the Deanery of Clinical Sciences. He is also Honorary Consultant Dermatologist at NHS Lothian and Principal Investigator at the Centre for Inflammation Research.
Dr. Weller serves as Programme Director for the M Med Sci at the University of Edinburgh and is President of the Scottish Dermatology Society. He is the Clinical Lead for the Dermatology Speciality Group at NHS Research Scotland, the Global Health Academy and Edinburgh Imaging.
Listen to the Podcast:
The podcast of this program will be available Monday, Sept. 1, 2025, after broadcast on Aug. 30. You can stream the show from this site and download the podcast for free.
Learn More:
Dr. Weller kindly shared links to some research by his colleagues that he mentioned during the show.
Here is an article by Joel Gelfland showing the benefits of home phototherapy for psoriasis.
This article by Adewole Adamson presents evidence that dark skin is not susceptible to UV-induced melanoma.
Download the mp3 of the show, or listen to the podcast on Apple Podcasts or Spotify.
Transcript of Show 1397: The Surprising Secrets of Sunlight’s Health Benefits
A transcript of this show was created using automated speech-to-text software (AI-powered transcription), then carefully reviewed and edited for clarity. While we’ve done our best to ensure both readability and accuracy, please keep in mind that some mistakes may remain. This transcript is copyrighted material. All rights reserved. No part of this transcript may be reproduced, distributed, or transmitted in any form without prior written permission.
Joe
00:00-00:01
I’m Joe Graedon.
Terry
00:01-00:05
And I’m Terry Graedon. Welcome to this podcast of the People’s Pharmacy.
Joe
00:06-00:27
You can find previous podcasts and more information on a range of health topics at peoplespharmacy.com. Do you avoid the sun? We’ve all heard that we should wear sunscreen all the time and stay inside from 10 till 2. This is the People’s Pharmacy with Terry and Joe Graedon.
Terry
00:33-00:45
Are there hidden health benefits from sunlight? Is it all about vitamin D? Why don’t supplements protect people against heart disease, cancer, diabetes, or depression?
Joe
00:45-00:52
New research suggests that some sun exposure may be helpful. Our dermatologist guest has done fascinating research.
Dr. Richard Weller
00:53-01:04
We have showed in Britain that after accounting for confounding factors, other factors, the more sunlight people have, the longer they live.
Joe
01:04-01:10
Coming up on the People’s Pharmacy, the surprising secrets of sunlight’s health benefits.
Terry
01:14-02:31
In the People’s Pharmacy Health Headlines, following a Mediterranean-type diet may help lower the risk of dementia in vulnerable people. People who carry a gene called APOE4 are particularly susceptible to developing Alzheimer disease. But an analysis of the Nurses’ Health Study and the Health Professionals Follow-up study published in Nature Medicine shows that those who come closest to a Mediterranean eating plan are less likely to come down with Alzheimer’s disease. There were more than 4,000 women and nearly 1,500 men included in the analysis, which covered three decades of data. People with two ApoE4 genes lowered their risk by 35% if they followed a Mediterranean diet high in vegetables, fruits, whole grains, fish, and olive oil. The lead author, Dr. Yuxi Liu, told CNN, “Not only did following a baseline Mediterranean diet reduce the probability of developing dementia by 35% in people with two APOE-e4 genes, but higher adherence to the diet further reduced their risk.”
Joe
02:30-03:36
The anti-vax movement has been gaining momentum, but there’s growing evidence that the shingles vaccine offers benefit far beyond protection against shingles. Several studies have demonstrated that the shingles vaccine can reduce the risk for dementia. A new study published in the journal Clinical Infectious Diseases reports that the recombinant herpes zoster vaccine Shingrix can reduce the risk of heart attack, stroke, and herpes zoster ophthalmicus, a potentially vision-robbing eye infection. The researchers compared over 100,000 vaccinated patients to over 400,000 unvaccinated patients. The median age was 68 years old. The average follow-up was two and a half years. The investigators concluded that two doses of Shingrix vaccine “were effective in preventing herpes zoster ophthalmicus in adults over 50, and were associated with significantly reduced risk of hospitalized acute myocardial infarction and stroke compared to unvaccinated individuals.”
Terry
03:36-04:27
The FDA has just approved a new and far more general indication for evolocumab, known by its brand name Repatha. Back in 2015, the agency approved this powerful injectable medication for lowering LDL cholesterol. At first it was used primarily for patients at high risk who couldn’t tolerate statins, or who didn’t respond adequately to statins for lowering cholesterol. Then the use was expanded to cover people with cardiovascular disease. Now, doctors can prescribe this medicine for any adult at risk for heart attacks, strokes, unstable angina, or other cardiovascular complications. Occasionally, people react to evolocumab with angioedema, which can be life-threatening. Such individuals will not be able to use it.
Joe
04:28-06:18
At one time, x-rays were the only tool doctors had to see inside the body. Since then, MRIs and CT or CAT scans have become widely available. Computed tomography imaging is performed on over sixty million patients annually. That number has increased by over thirty percent since 2007. Such images can be extremely helpful in making a diagnosis, but there are risks that many patients may not realize. The name CAT scan sounds innocuous, but in fact it represents ionizing radiation similar to X-rays. An investigation published in JAMA Internal Medicine projected the number of future cancers due to this radiation exposure. The researchers used data from the University of California, San Francisco International CT Dose Registry and modeled the effects of the radiation. They estimated that approximately 103,000 cancers are likely to result from the 93 million scans conducted in 2023 on 60 million people. The risks are highest in children and adolescents, but many more adults undergo CT scans. The scientists conclude that if current practices persist, CT associated cancer could eventually account for 5% of all new cancer diagnoses annually. And that’s the health news from the People’s Pharmacy this week.
Joe
06:15-06:17
Welcome to the People’s Pharmacy. I’m Joe Graedon.
Terry
06:18-06:35
And I’m Terry Graedon. For decades we’ve been told to stay out of the sun, especially in the summertime. If we venture out, we need to be wearing protective clothing, including a hat and high-SPF sunscreen. If we’re good, we’ll never get a tan in the summer.
Joe
06:36-06:51
Dermatologists worry about sun exposure because ultraviolet radiation is damaging to the skin. It causes premature aging and is linked to various forms of skin cancer, including the most dangerous, melanoma.
Terry
06:52-06:57
But could sunlight be more complicated? Does it have hidden health benefits?
Joe
06:58-07:24
To learn more about this very controversial topic, we turn to Dr. Richard Weller. He is a professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology at the Deanery of Clinical Sciences. His research interests include eczema, psoriasis, and the effects of sunlight on human skin.
Terry
07:24-07:28
Welcome to the People’s Pharmacy, Dr. Richard Weller.
Dr. Richard Weller
07:29-07:32
Hello, it’s very nice to be talking to you today.
Joe
07:32-07:40
Dr. Weller, there’s a rumor that you are a dermatologist. Do I have that right?
Dr. Richard Weller
07:41-07:52
I am. I’m perhaps not a conventional dermatologist in some of my views, but those have really developed over the years as a consequence of my research.
Joe
07:53-08:43
Well, speaking of your research, it kind of contradicts what American dermatologists have come to believe, which is: If you could just live in a cave, that would be ideal because that way you would never be exposed to ultraviolet radiation. In other words, sunlight. And the only time you’re allowed to go out in the sun is if you have slathered on a high SPF sunscreen, 50 or above. And definitely avoid being outside between 10 and 2 because sun is your enemy. It’ll cause cancer, it’ll cause wrinkling, it’ll mess up your life.
Terry
08:42-08:43
You are exaggerating.
Joe
08:44-08:44
Of course.
Terry
08:44-08:46
But not by very much.
Joe
08:46-08:58
So you’ve kind of come up with a different perspective, Dr. Weller. Can you tell us a little bit about your time in Australia and why that started you down this path in part?
Dr. Richard Weller
08:59-10:30
Sure. I mean, I think you’re you’re pretty accurate about the American dermatology view to sunlight. And I think what I really want to say is we need a more nuanced view on sunlight. And of course, the second thing to say to you is that I’m speaking to you from Scotland, and people forget how much further north Europe is than Scotland [Scotland is than the US]. So you know, the further away you are from the equator, the less sunlight there is. And as an example, if you live in the cold woolly fringes of Maine or New England, you’re actually at the same latitude as the Côte d’Azur, as Cannes, right down on the Mediterranean coast of France. And if you live in Florida, you’re on the same latitude as the Sahara. So the amount of sunlight Americans are getting is way more than we North Europeans are getting. So I’m speaking to you with someone from Scotland and probably what I see is different from what my American colleagues see. Nonetheless, sunlight has significant health benefits, as my research and that of other colleagues around the world is now showing. There has to be more to the message we give than just ‘sunlight is bad’ because that’s becoming outdated. And that’s really the message I’d like to get across.
Terry
10:31-10:38
I wonder if you could summarize for us, Dr. Weller, what some of those benefits of sun exposure might be.
Joe
10:38-10:45
And in particular, can you tell us a bit about Australia and cardiovascular disease?
Dr. Richard Weller
10:46-11:46
Sure. So yeah, I mean so look, I I suppose a bit about my career. I’m an academic dermatologist. I’ve been a dermatologist for about 30 years. Before I became a dermatologist, I did an internal medicine training and as part of that I worked in Australia, in Northern Australia and Queensland for a year. And Australia is much sunnier than the UK. So in Cairns, where I was living- the UV index is seven or above every single day of the year. So in mid-winter, the UV index, which is a measure for the burning ability of the sunshine, hits about seven, you know, for an hour or so around midday, and it rises to fourteen in midsummer. So in Scotland last year, the UV index hit seven for ten minutes. It was just after lunchtime on the 24th of June, if you want to know exactly when.
Terry
11:47-11:47
Okay.
Dr. Richard Weller
11:48-13:58
And yet we are given sunlight protection advice copied directly from the historical Australian advice. Designed for white Australians, you know, Australians of North European heritage who’ve moved to somewhere hugely sunnier and that is inappropriate [in Scotland]. You know, skin color is an evolutionary adaptation to sunlight. So, you know, Homo sapiens, that’s us, we’re about 160, 200,000 years old as a species. Non-African humans are the descendants of people who left Africa about 60,000 years ago And what is interesting is those humans who’ve moved to high latitude, so Europe and China, modern China have independently evolved pale skin repeatedly on moving to low light environments. So the pale skin gene variants that we see in Europe, um SLC 45A2 in particular, arose about 8,000 years ago. Independently pale skin gene variants arose in humans who had moved to high latitude modern China. So skin color determines your response to sunlight. That’s that’s what it’s about. And what’s happened is repeatedly humans who’ve lived in low-light areas have there’s been an evolutionary fitness advantage to getting to to developing pale skin which allows you to get more of sunlight’s benefits. But at the same time, if you fly down to or go by convict ship from Britain to Australia you’re very suddenly moving to somewhere with way more sunlight than your skin um is adapted to manage. And that’s when you see the problems of skin cancer and and sunburn and so on. Texas is the same as Australia in that sense.
Terry
13:59-14:38
Now, Dr. Weller, as an anthropologist, I’m familiar with what I guess is uh the hypothesis that as you say, uh, pale skin is an evolutionary adaptation to not getting enough sunlight, and therefore when we expose our pale skin to the uh sunlight that we can get in uh you know, North Carolina or New Jersey or France or where have you, we’re able to make the vitamin D we need. Are there other considerations beyond vitamin D?
Dr. Richard Weller
14:39-17:39
Yes, very much so. And of course the key question is, you know, that there must be a benefit because it keeps occurring. What are those benefits? And I and I have to say straight off, I think the benefits of vitamin D are hugely overstated. Vitamin D is less important than we have thought for much of the last hundred years. So we look, it may have played a part in the development of pale skin. We know that people with darker skin need more sunlight to get the rise, same rise in vitamin D. But you know, we don’t in Britain nowadays see rickets or problems that associate with vitamin D deficiency in African, you know, British African communities, for instance. And actually, skin color doesn’t enormously affect vitamin D synthesis. A lot of my research about sunlight has been looking at cardiovascular disease. We find that sunlight lowers blood pressure independently of vitamin D. There’s a substance called nitric oxide, which my research has shown is stored in the skin, and when sunlight hits the skin, it releases that nitric oxide, the circulation where it dilates blood vessels and lowers your blood pressure. And that has really quite a big effect at population level. So again hit here in Britain The average blood pressure is six millimeters of mercury systolic lower in summer than winter. And that appears, that’s probably a nitric oxide effect. It’s definitely not a vitamin D effect. In terms of the evolutionary history of skin, that gets more interesting. My feeling is that heart disease, blood pressure, high blood pressure related disease like heart attacks and strokes is unlikely to have been a problem in evolutionary times. You know, chasing after woolly mammoths, running away from saber toothed tigers. Pre-the invention of cigarettes, I think it is unlikely that heart disease was a big problem. What I’m looking at now with my research is we wonder if infection may have played a role. Because what’s fascinating is humans have been in Europe for about 40,000 years, been in Asia for about 60,000 years. And yet the development of those pale skin gene variants in Europe only starts about eight thousand years ago, and initially the that the that the white skin gene variants arise in in the fertile crescent, you know. Anatolia. And those white skin gene variants arise in East Asia around eleven thousand years ago. And it it arises at the time when we make the shift from being hunter-gatherers to farmers.
Terry
17:40-17:57
You’re listening to Dr. Richard Weller, Professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology in the Deanery of Clinical Sciences and participates in the Center for Inflammation Research.
Joe
17:58-18:07
After the break, we’ll find out more about how farming might have contributed to evolutionary changes in skin color.
Terry
18:07-18:11
Dr. Weller offers us a summary of the health benefits sunlight can provide.
Joe
18:12-18:16
Lack of sun exposure is actually associated with some health problems.
Terry
18:17-18:22
Studies on sunshine are mostly being done in the UK and Europe, not in the US.
Joe
18:22-18:31
Dermatologists sometimes suggest we could just take vitamin D supplements to make up for lack of sunlight. Why isn’t that adequate?
Terry
19:45-19:48
Welcome back to the People’s Pharmacy. I’m Terry Graedon.
Joe
19:49-20:12
And I’m Joe Graedon.
Terry
20:13-20:28
Why do people who live in northern latitudes tend to have pale skin? Presumably, there’s some evolutionary advantage. Anthropologists have suggested that pale skin is better at making vitamin D when sunlight is scarce.
Joe
20:29-20:49
Many dermatologists encourage people to avoid the sun as much as possible. To make up for the possible lack of vitamin D, they suggest taking vitamin D supplements. But research on vitamin D pills or injections has been strangely disappointing. Why would that be?
Terry
20:49-21:18
Does sun exposure have any other physiological effects beyond triggering vitamin D synthesis? Dermatologist Steve Feldman of Wake Forest University has found that Ultraviolet exposure can boost psychological mood, making people feel more relaxed. He also found it can help people with chronic pain such as fibromyalgia feel more comfortable. Our guest today has also been studying the impact of sunlight on skin for years.
Joe
21:18-21:40
We’re talking with Dr. Richard Weller. He’s professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology at the Deanery of Clinical Sciences. His research interests include eczema, psoriasis, and the effects of sunlight on human skin.
Terry
21:41-21:55
Dr. Weller, how would the rise of uh domestication and farming tie in to a change in skin color? How does that make sense?
Dr. Richard Weller
21:56-24:58
Yeah well this is the really interesting thing because being at high latitude, low light, by itself has not driven a move to pale skin. Because humans have been 40,000, you know, I mean if you go to the Dordogne in France, the amazing cave art, you know, the wonderful pictures of woolly mammoths and so on and ancient animals on the roofs of the caves, dates back twenty thousand years ago, when actually the people who painted that were dark-skinned. So this this move to, so it’s not just being at high latitude, because most of the time that Europe’s been inhabited, it’s been inhabited by dark-skinned people. And it’s not just being a farmer, because farming has arisen independently. I mean farming arose independently in what’s now Mexico, maize; it’s arisen independently in India; it’s arisen independently in Papua New Guinea. So either by themselves does not precipitate that move to pale skin. It’s when the two come together. It’s when you’re a farmer in a low light environment that pale skin arises. So that sort of information sets the question. It doesn’t give the answer.
It is possible that part of it’s dietary, you know, we know that that Neolithic transition from being a hunter-gatherer to a farmer actually led to a poorer diet. shorter people, probably higher infant mortality. You know, it wasn’t all milk and honey when we moved to being farmers. So it could be a dietary factor, it could be related to vitamin D. Sorry, vitamin D for an American audience. My but I have to say my feeling is it may be or it is likely to be infection. Because the thing that really happens when you make that Neolithic transition shift is that’s the advent of infectious disease. Because most infectious disease comes from animals, what we call zoonotic. You know, COVID comes from bats, TB comes from cows, influenza comes, you know, most infectious disease comes from animals. And when you’re a farmer, you’re living with animals. And the other thing, of course, is when you’re a farmer, you’re living in communities, you’re living in villages close to other people, rather than being hunter-gatherer bands dispersed across the landscape. And so most infectious disease arises from that time, we think. And I suspect that there are UV-driven processes which reduce infection. And that’s what we’re really looking at at the moment. And the point about skin color is it mediates your response to sunlight. It’s not pale skin itself that prevents you get infections. It’s the fact that pale skin allows you to maximize the biological effects of sunlight.
Joe
24:58-26:23
Dr. Weller, I’d like to go back and sort of summarize, if you don’t mind, all of the benefits of exposure to sunlight, because as I introduced a little bit tongue in cheek, American dermatologists believe that that sunlight is problematic, that it will cause all kinds of problems, and that we need to use these high SPF sunscreens or better yet stay out of the sun completely. So you’ve already suggested that blood pressure is affected by exposure to sunlight. You’re now alluding to the possibility that our immune system may be enhanced by sunlight, but there are a whole lot of other conditions as well. I think about inflammatory conditions like arthritis. I think about autoimmune conditions like eczema. I think about kidney disease and osteoporosis and diabetes. So can you just sort of summarize all of the potential health problems associated with lack of exposure to sunlight? How people in Australia may be quite different from people in Greenland, in terms of their risk of heart disease? So give us that big perspective.
Dr. Richard Weller
26:23-32:25
Yeah, look, I’m delighted to and of course I’ve start I’ve jumped straight into where my my current research is because that’s really exciting. So so sunlight’s got ups and downs, got a good side and a bad side. So look with my dermatologist hat on broad brimmed shady hat. Sunlight is a risk factor for skin cancer and it is a risk and it leads to skin aging. So that’s the kind of downside. But it’s also got an upside.
There is a wonderful means about looking at how do these risks and benefits weigh out. And that’s what we call all-cause mortality: death from any cause. And that gives you very robustly a summation of those two factors, the pluses and the minus. So we have a paper coming out actually next week. We’re just uh arranging uh stuff with the journal at the moment. which touches on this subject, but the first person to look at it uh was a colleague and friend of mine, Pelle Lindqvist, who is an obstetrician in Sweden. And he did a wonderful study called the Melanoma or the Melanoma in Southern Sweden study. So this was set up in 1990. It was designed, as the name suggests, to find what causes melanoma, and how does it kill people. And 30,000 Swedish women, 30,000 middle-aged Swedish women in southern Sweden. So that that at the time was a quarter of the population of southern Swedish and middle-aged women were recruited in 1990 and they were asked a series of questions about how much sunlight they got. But they were also asked an extensive range of other questions asking about lifestyle factors, education, income, health, you know, other smoking habits, medical conditions. So the baseline information was taken, they were then followed for 25 years, and then the investigators went back to find out what had happened to them. And the first thing to say is that those had most sunlight were more likely to have had a case of melanoma. But Pelle’s interest and my interest is what about the deaths? I’m not interested in cases of the diseases. I’m interested in death from any cause. And there, much to the surprise of the dermatologists who set the study up, the direction was in the opposite direction to melanoma cases. They found that the women who had the most sunlight after correcting for all of these other factors, you know, income, education, smoking, etc. , etc. , those that had the most sunlight were half as likely to be dead. 25 years after the study started, as those who had the least sunlight.
So that’s the first study. We have just done a much larger study looking at the UK Biobank. So the UK Biobank, uh half a million middle aged people in Britain were recruited (I was one of them) and examined in great depth over about it took about four years to recruit the whole cohort, um, all around Britain. And every subject went up to an investigation center where there was about three hours of questionnaires, investigations, measurements, you know, mass of information taken. And that was back in 2000 and uh, anyway, about about 20 years ago. And those people have followed up long term. And we have gone into that database and we’ve taken 400,000 people from that, and we have looked at measures of sunlight exposure. So the measures of sunlight exposure we have used have been how far south people live in Britain, because the further south you live, the more sunlight you get. And our other measure actually was people who use sun beds, not so much because of the sun beds themselves as because behaviorally we know that people that use sun beds sunbathe more, actively seek the sun more. Now, we then had to correct for all the confounders. You know, sun bed users are younger, more female, less educated, more likely to come from Manchester, etc etc and we had to correct for the same factors the further south people lived. And what we find is that the more sunlight people get the longer they live. They have a reduced all-cause mortality. They have a reduced cancer mortality.
Melanoma is an interesting one. There was an increase in diagnoses of melanoma in those that got more sun, but no increase in mortality from melanoma and pretty much all the other cancers had a reduced mortality. And cardiovascular mortality was also greatly reduced. So just as Pelle showed in Sweden, we have showed in Britain that after accounting for confounding factors, other factors, the more sunlight people have the longer they live. Now one big caveat I’m gonna throw in for your audience is these are North European studies. And our sunlight levels here are much lower than your levels in America. You know, white skin has developed in Europe because we don’t have much sunlight. And this data applies here. I’m not sure how much it’s going to apply in America. And of course the studies haven’t been done because all people have thought about sunlight is oh gosh, it’s dangerous, it’s bad. But really interesting. Certainly for us in northern Europe, I think a really important, really important finding.
Terry
32:26-32:46
So you’re not aware of any American colleagues who are doing anything similar? Of course, we don’t have a resource like the UK Biobank, which is an extraordinary resource of a huge amount of information, I don’t believe anything of that sort has been collected in the US.
Dr. Richard Weller
32:47-35:46
No, I mean these studies can’t really be done in America. I mean most of these studies come out of Scandinavia and Britain because we have universal health systems. So if you get sick or have disease or die, you know, all our data are collected centrally. America has such a bizarre health system and it’s so fractured and broken up into small things, it’s not really possible to do there. What America has been very good at at doing though is things like clinical trials and I need to mention vitamin D, vitamin D. Because the other thing to say here is vitamin D’s benefits have been vastly overplayed. Now we know that so sunlight is responsible for making vitamin D. Vitamin D has some important benefits, rickets, you know, it prevents rickets. And we know that when you measure vitamin D People with higher measured vitamin D levels are healthier in almost every way you can mention. Less heart disease, less strokes, less multiple sclerosis, less diabetes, etc. , etc., etc. The problem is when you give vitamin D, there are you know, it prevents rickets, which we’ve known for a hundred years. And there is an enormous rearguard action going on by the vitamin D industry saying, oh, well, what about this? What about this? What about this? Um and the vitamin D industry, I mean it’s a it’s worth, I think, it’s about two billion dollars a year. It is a huge industry.
The biggest study of all on vitamin D supplementation was run in America. You’re fantastic at this, you know, NIH comes in with its funding. And there was a study called the Vital Study, run by Joanne Manson 25,000 Americans, 25,000 adult Americans were recruited. Half of them were given vitamin D supplements for five years and half of them were given a placebo, a sham control. And at the end of five years and really the study has now ended, but the patients are being followed up. And what it confirms, and it confirms the findings from lots of other smaller studies, is vitamin D has absolutely no effect on heart disease, on strokes. Probably doesn’t do much for cancers. Um, you know, the results came back negative, negative, negative. And there was an editorial in the New England Journal of Medicine 18 months ago. summarizing all this saying stop taking vitamin D supplements. You know, unless you are one of those very few people with incredibly low levels of vitamin D, it’s not doing anything. And people come up saying I’ve got vitamin D deficiency. And you say, what do you mean? Oh, I had a blood test. Doctors do not treat blood tests. We treat disease. A blood test is not a disease. You know, you wouldn’t know if you hadn’t had it done. But there is a huge industry out there pushing this.
Terry
35:46-36:11
So, Dr. Weller, we actually have spoken with uh Dr. Manson and with one of her colleagues, and there was one area in which the VITAL study showed some benefit for vitamin D supplements and that was it reduced the likelihood that someone would be diagnosed with a new autoimmune condition. So you know…
Dr. Richard Weller
36:12-37:16
Yes, I look I’m I am not saying vitamin D is absolutely irrelevant. I think we know about rickets, the autoimmune condition is is interesting. But the vast array of benefits that have been claimed for vitamin D are not held up by that amazing study. So what is interesting is that sunlight acts in multiple ways. Now a bit of it is vitamin D. but there’s so many other areas by vitamin D independent mechanisms. And that’s really exciting. And the problem is our focus has been so much exclusively on vitamin D. We have just ignored this. We’ve said, oh yeah, I know the fact that people are healthier. It’s vitamin D. Live in a cave, take vitamin D supplements. And those vitamin D supplements only account for some of sunlight’s benefits. And we need to move on and look for what the other mechanisms are.
Terry
37:17-37:36
You’re listening to Dr. Richard Weller, Professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology in the Deanery of Clinical Sciences and participates in the Center for Inflammation Research.
Joe
37:36-37:42
After the break: Why can’t we compensate for sun exposure by taking vitamin D supplements?
Terry
37:43-37:48
Well, could it be that maybe, as doctor Weller says, vitamin D is just a marker for sun exposure?
Joe
37:49-37:51
What exactly does that mean, a marker?
Terry
37:52-37:58
Well, it means we can measure vitamin D, and there are things we can’t measure. We don’t measure nitric oxide that well.
Joe
37:59-38:02
Well, what’s a reasonable amount of sun exposure?
Terry
38:02-38:10
We’ll also find out more about Dr. Weller’s research on how sunlight triggers nitric oxide formation and how that affects us.
Joe
38:10-38:15
What does nitric oxide do for the immune system?
Terry
38:32-38:37
You’re listening to the People’s Pharmacy with Joe and Terry Graedon.
Joe
38:45-38:48
Welcome back to the People’s Pharmacy. I’m Joe Graedon.
Terry
38:48-39:13
And I’m Terry Graedon,
Joe
39:13-39:34
Today on the People’s Pharmacy, we are exploring the controversial concept that some sun exposure might have hidden health benefits. Of course, we want to emphasize that no one should get burned by the sun. In addition to being painful, sunburn creates the risk for melanomas.
Terry
39:34-40:04
To find out more about phototherapy and how ultraviolet light acts to produce nitric oxide in the skin, we turn back to our conversation with Dr. Richard Weller. He’s a professor at the University of Edinburgh College of Medicine and Veterinary Medicine, and holds the personal chair of medical dermatology in the Deanery of Clinical Sciences. He also participates in the Center for Inflammation Research.
Joe
40:05-40:59
So Dr. Weller, you have just put into perspective the fact that vitamin D is not the answer to lack of sun exposure. And I want to just quickly go back and summarize all of the benefits of sunlight And what happens when you don’t get exposed to sunlight? And you’ve alluded to things like hypertension, cardiovascular disease, cancer. You’ve mentioned kidneys, you’ve mentioned diabetes. What about autoimmune conditions such as multiple sclerosis? What about eczema, which I believe is something that you have a lot of experience with? Tell us why sunlight is so important for our body’s health.
Dr. Richard Weller
40:59-45:54
Yeah, great question, thank you. And I’m delighted you bring multiple sclerosis up. So multiple sclerosis It is the classic sunlight deprivation disease. So, you know, even when I was at medical school, and that was a frighteningly long time ago, We knew that MS was a disease that was most common in people who grew up in areas without much sunlight. So I’m in Scotland and we have the highest rates of MS in the world here. And in fact, the highest of the highest is the Orkney Islands, which are just off the north of Scotland. Beautiful place. But something like I think about one in eight hundred people there has MS. Incredibly common. So a colleague and friend of mine, Prue Hart in Australia. And so and again, the classic story. people with low measured vitamin D levels are more likely to get MS. You give vitamin D you know, kinda iffy you know, the the observational effect is huge. This huge great relationship measured vitamin D. You give vitamin D supplements, not very much happens. So it’s got to be more than just the vitamin D.
And I might say there’s a super company in America, Cytokines, led by a wonderful guy John McMahon, which is setting up a phototherapy study of MS in the United States. So there’s really good preliminary work done in Australia where people who when they had their very first diagnosis of MS, their very first demyelinating episode, were randomized either to get phototherapy, the kind of stuff that dermatologists use on their offices, well established, incredibly safe treatments, They were randomized either to get phototherapy or to get a control. And there was a really strong move towards a reduction in progress of MS, and a really marked improvement in the the biomarkers that are a good indicator of whether people are going to progress or not. Really exciting. The big problem, of course, was it was done in Australia. So your control group not getting phototherapy, well, they’re still in Australia under quite a bit of sunlight. And of course the other reason there isn’t much MS in Australia. It’s a very sunny country. There’s masses in Britain. So John McMahon and his company are leading this to me really exciting trial of phototherapy for MS in America. And I am watching with huge, I mean just really exciting, because here is a disease which should absolutely go along with phototherapy. And also the narrowband UVB phototherapy that we dermatologists use to treat eczema and psoriasis. has been around for twenty or thirty years incredibly safe. I think utterly over-medicalized. I mean It’s been around for 20 or 30 years. There’s no signal for skin cancer being found in Britain for people having UVB phototherapy. So it’s sunlight. We don’t see a skin cancer signal. And yet you have to see a doctor. You have to see a dermatologist to get it. Um, I think it should be used far more widely.
Great American dermatologist called Joel Gelfland, again, fantastic guy. Has just done a wonderful trial of home phototherapy, people with phototherapy lamps at home. And he’s compared how well they do to people who go to their dermatologist office to get phototherapy. And he finds people with their lamps at home do amazingly well. They do as well in terms of reduction in their psoriasis as patients receiving these biologic treatments, these incredibly expensive but highly effective monoclonal antibody treatments. Well actually phototherapy, Joel showed, is as good. And I might say a fraction of the cost and, you know, I mean basically it’s it’s sunlight in a box. And I think we greatly underuse it. And we underuse it because we’ve demonized sunlight. So here is a sunlight-based treatment. And of course, that really threw dermatologists in the quandary. Hang on. We run around saying Don’t go in the sun. And then suddenly we’ve got a treatment which is based on ultraviolet. What do we do? What are oh no, we’re gonna surround it with caveats and cautions and warning signs. I think we’ve gone completely overboard with that and it means we are not using this safe and effective and clean treatment nearly as much as we should be. So I’m delighted that people like Joel Gelflands as a dermatologist and John McMahon with his MS studies is really restoring, you know, kind of rejuvenating this wonderful and underused treatment modality.
Joe
45:54-47:02
Dr. Weller, I want to come back to your research with nitric oxide, because I’ve been fascinated by nitric oxide for decades. But first, you know, w we’ve been talking about sunlight exposure, and for the most part Americans have a kind of love-hate relationship with the sun. They want to go out to the beaches, they wanna play outside, they wanna be golfing and playing tennis and going for hikes. But they wouldn’t dare go out without their SPF 50 or 100. I’m just wondering, can you give us some practical guidelines about how we can expose our skin to sunlight for a quote unquote reasonable or safe amount of time that won’t do damage, that won’t burn our skin and lead to wrinkling and squamous or basal cell carcinomas. How do we use the sun without getting into the sunbox that you were talking about a moment ago in in a safe way?
Dr. Richard Weller
47:02-48:45
Yeah, I mean a really good question. I mean the really key thing is to avoid sunburn and particularly for children to avoid sunburn because it’s sunburn particularly in children which is the major risk factor for melanoma, the serious skin cancer. Sunlight is photoaging. Sunlight is a risk factor for skin cancer. And you know, non-melanoma with skin cancers in particular, the more sunlight you get, the greater your risk. Look, I uh you know I have a kind of conflict of interest in here because I have, I’ve developed a a a compound you can add to sunscreen that will release nitric oxide in the sunscreen. You know, it’s it’s sort of in development. We’d love to get it out there. I I think sunscreens could be better than they are. I mean at the moment sunscreens are all about blocking sunlight, and blocking the sunlight will reduce the aging, it will reduce the burning, it will reduce the cancer. My concern is it’s also going to block the good things. I think sunscreens could be better than they are. It certainly my, in Britain I am pretty quite relaxed about sunscreen use because we live in a much less sunny place than it than America. Um in America you do have an awful lot of sunlight. Now I suppose what I’m going to say is more research is needed. I think sunscreens could be better. I think we haven’t looked hard enough at the benefits of sunlight and how much sunlight is required to get them to be able to give a really robust answer. And the reason we haven’t done that is because we’ve purely been focused on sunlight is bad, vitamin D will make up for the absence of it. And clearly the story is much more nuanced and complex than that.
Joe
48:46-49:07
Well, even if you are unwilling to make a recommendation because there’s a lack of science. What would be a reasonable amount of sun exposure, and at what time should we contemplate that sun exposure if we want to avoid sunburn and some of those damages you mentioned?
Dr. Richard Weller
49:07-51:42
Well if you live in Florida or Texas you’re gonna need some protection. You’re living in an African latitude, and if you’ve got white skin, you’ve got you I think you’ve just got to be protecting your skin a great deal out around the middle of the day. If you’re farther north, you know, it gets less of an issue, but you’re still in a very sunny climate I think Americans do need more sun protection than Europeans because you live so far south. And of course the other thing is skin color. Because um so really I work in Ethiopia a lot, although sadly with the political situation there, uh not for the last three or four years. So UV-induced melanoma really does not occur in dark-skinned people. Jay Adamson, a wonderful dermatologist, American dermatologist in Texas, has really shown that UV-induced melanoma does not occur in African Americans. When I work in Ethiopia, we do not see UV-induced melanoma. On at two and a half thousand meters altitude, eight thousand feet, in the tropics in Ethiopia. Incredibly sunny is the point. Dark-skinned Ethiopians do not get UV-induced melanoma. They get these rare subtypes of melanoma, not related to sunlight, but but skin color really determines your risks of of skin cancer. And I am concerned by the way that the American Academy of Dermatology regards all skin types as the same when it comes to sun protection Because certainly the work that we have done uh in America. So we looked at how sunlight lowers blood pressure in America, a big study on three hundred and thirty thousand Americans. And we showed that African Americans need more sunlight to lower their blood pressure than white Americans. So just as skin color determines your risks of getting skin cancer, It also determines how much UV you need to get the benefits of sunlight. You know, skin color is all about response to UV. And I am concerned that by putting out the same message to everyone of every skin color, that’s not wise because that risk-benefit ratio for sunlight is absolutely determined by your by your skin color. And it needs to be a different message dependent on your skin color.
Joe
51:42-51:56
Dr. Weller, we just have a couple of minutes left. I wonder if you could briefly summarize your research with nitric oxide and why it’s so incredibly important for so many physiologic functions.
Dr. Richard Weller
51:56-53:20
Yeah. Well the biggest killer in the world today is heart disease. So half, basically half of deaths in the world are caused by high blood pressure-related diseases, heart attacks and strokes. Sunlight lowers blood pressure and with it the risk of having a stroke or a heart attack. And the mechanism by which it does it is release of nitric oxide from the skin into the circulation. Hugely important. If you’re a male in Scotland, you are 30% more likely to drop dead of any cause in a week in December than a week in July. I’m pretty mellow at the moment, It’s July, It’s a good time of year. I’ll get through to the end of the week. I start getting a little nervous as the year gets later. And a lot of that is driven by nitric oxide from the skin and its effects on the cardiovascular system. So it’s not sunlight has benefits as well as risks. Those benefits are not just vitamin D. There’s other mechanisms. The mechanisms include importantly for cardiovascular disease, nitric oxide, but also I suspect other mechanisms that really just started to look at, like immune function in particular. So I really think we need to be reconsidering our approach to sunlight in a more balanced way, considering benefits and not just risks.
Joe
53:21-53:47
And Dr. Weller, in the one minute we have left, the role of sunlight and perhaps nitric oxide on the immune system, because goodness knows, we have certainly learned a lot from COVID-19 and the pandemic. A lot of people would prefer to reduce their risk from infection. How does sunlight help there?
Dr. Richard Weller
53:47-55:33
So well so interesting. So, so we looked at so we um at at the same time as, uh as a rival group in Harvard were looking at the effects of sunlight on COVID mortality. And we found in the very first three months of the pandemic that the sunnier it was after accounting for other factors, the less deaths there were from uh COVID. And that the Harvard group showed that the more sunlight there was, the less growth in cases. Now that’s observational studies, but we uh colleagues in America ran a pilot study in Louisiana giving phototherapy or, or a control to patients admitted to hospital with COVID. And it was a small study, only fifteen in each group, but they found a trend to reduce deaths in the sunlight group. And the third bit of evidence is people with high measured levels of vitamin D were less likely to get COVID or die of it, but multiple trials giving people vitamin D supplements, it had no effect. The usual story, measured vitamin D is a marker for sunlight exposure, not necessarily causative. So look, so I think there’s some really interesting data there suggesting that sunlight is driving processes which we’re now looking at that reduce your risk um of death from COVID. And that may apply to other infectious diseases, but the work needs to be done. And I suspect in evolutionary terms, that’s what has driven this move to pale skin in humans who move to low light areas.
Joe
55:33-56:04
So, Dr. Weller, you’ve described the benefits of sunlight as being more than just vitamin D.
Dr. Richard Weller
55:42-55:43
Yep.
Joe
55:43-56:04
That nitric oxide is also a critical factor, and it’s manufactured in the skin and then circulates in the bloodstream and lowers blood pressure and probably has a lot of other benefits as well. What else is going on? Do we know what sunlight exposure does beyond vitamin D and nitric oxide?
Dr. Richard Weller
56:04-59:08
Yeah, uh well I, I strongly suspect it’s having effects on the immune system and and in fact we’ve got f Pretty good evidence showing that. And that’s what I’m actually looking at at the moment with my current PhD student. So we’re so a really good early study in this area which we’re building on now by a chap called Dopico in Cambridge. Came to I think into Edinburgh actually. And he did one of these studies where you use other people’s data um very well. And they looked at um gene expression patterns in blood. Now what they did was they used about eight studies where people had had blood, and the studies have been done for various reasons. Everybody had their blood taken throughout the year during these studies, and the gene expression pattern, what genes were turned on and off in the whole blood, um, was looked at. And what Dopico and colleagues did was they looked, they analyzed the gene expression in these data sets by the month of the year in which the blood was taken. The studies were done for different reasons, but they happened to run over 12 months. And so he went in and thought, gosh, I’ll just analyze it by month of the year. And what he showed was that 30% of all the genes in your blood, you know, which are uh immune genes are very important there, show seasonal variation. So there is a huge uh seasonal variation, possibly I would imagine sparked off by UV, uh which occurs in immune cells. And broadly what he found was that inflammatory genes were turned on in winter and anti-inflammatory genes in summer. And the the, they suggest that maybe, you know, infectious disease flies around in winter. Maybe your body turns up the immune system to be able to jump on infectious disease. That was the hypothesis. So there’s now a technique called single cell RNA sequencing where you can look at every single individual cell, and so you can take, draw blood, you can look at ten thousand different cells, and you can look at every single gene turned on in every single cell. So the experiments I’m doing at the moment we do in winter. We take healthy volunteers. We load them up with vitamin D at the beginning, so they’re full of vitamin D at the start. Take their blood, look at all of their gene expression pattern, we then give them two weeks of daily solar-simulated UV, as if they were on in the Mediterranean, and we then repeat it. And we’re early days, don’t want to talk about the results yet, but we’re getting very interesting effects on gene expression patterns in in immune genes, T cell genes in particular. So it looks as if sunlight has significant effects on the immune system. And we’re really we’ll see where it takes us, but but really exciting stuff.
Joe
59:08-59:53
Dr. Weller, if we were to dial back, what, 100, maybe 150 years to a day when tuberculosis was rampant and a terrible killer around the world. There were sanatoriums where people would go and they were often exposed to sunlight. Even in the winter, they would take people outside, bundle them up and exposed them to the sun, they somehow thought that exposure to sunlight could help people dealing with tuberculosis recover or at the very least survive better. Did they know something we didn’t know?
Dr. Richard Weller
59:53-01:02:34
Yeah, I mean it’s really interesting and and I think sadly they never did, they had not yet invented robust, placebo-controlled clinical trials as we would understand them. But they weren’t fools. And of course, places like Davos, now an expensive ski resort and uh financial center. Davos was set up initially as a heliotherapy center, a center where people would go to get the sunlight for their tuberculosis. I I gave the opening address at the meeting of the Swiss the annual meeting of the Swiss Dermatology Association last year. And I pointed out and I was talking about the work we’ve been discussing today, and I pointed out to them that had I been there a hundred years ago, I would have been going as a disciple of the great Rollier, you know, the Swiss doctors who developed heliotherapy to treat tuberculosis. And instead, here I was a hundred years later, coming along to remind them of what they’d done previously. So absolutely, you know, we had it, you had it in America, we had it here in Britain. That was before antibiotics, the treatment for tuberculosis. And of course, and then for tuberculosis of the skin, a chap called Finsen in Denmark, developed ultraviolet lamp treatment for treatment of lupus vulgaris, tuberculosis of the skin. And he actually got the Nobel Prize for Medicine for this in I think it was 1904, really one of the very early Nobel Prizes for Medicine. So there is actually a history of UV having been used to treat infectious disease. And certainly since then we’ve had antibiotics and vaccines and we’ve had sewers and we’ve had clean airs, you know, we’ve had all of these measures that have reduced infectious disease death now. You know, the miracle of vaccination has basically eradicated infectious disease from our day-to-day life. So COVID was, I mean it was very tragic. It was also scientifically very interesting because suddenly you had a new infectious disease against which we had none of our usual defenses. You know, before the vaccines came, it was us and the virus. And you began to be able to see what happens to populations with a new virus. And it certainly looks as if those that had more sunlight had less deaths from COVID. And that for me was really very interesting. What the mechanisms are, we don’t yet know, and that’s what we’re looking for now.
Terry
01:02:34-01:02:41
Dr. Richard Weller, thank you so much for talking with us on the People’s Pharmacy today.
Dr. Richard Weller
01:02:41-01:02:44
Well thank you. I’ve enjoyed the conversation.
Joe
01:02:44-01:03:15
You’ve been listening to Dr. Richard Weller, professor at the University of Edinburgh, College of Medicine, and Veterinary Medicine. He holds the personal chair of medical dermatology in the Deanery of Clinical Sciences and participates in the Center for Inflammation Research. The show notes for today’s show have a link to the recent article in The Economist about his research and a link to his paper in the Journal of Investigative Dermatology.
Terry
01:03:15-01:03:26
Lynn Siegel produced today’s show. Al Wodarski engineered. Dave Graedon edits our interviews. B. J. Leiderman composed our theme music.
Joe
01:03:26-01:03:32
This show is a co-production of North Carolina Public Radio, WUNC, with The People’s Pharmacy.
Joe
01:03:57-01:04:12
Today’s show is number 1397. You can find it online at peoplespharmacy.com. That’s where you can share your comments about today’s show. You can also reach us through email radio at peoplespharmacy.com.
Terry
01:04:12-01:04:32
Our interviews are available through your favorite podcast provider, and now you can find them on YouTube as well. You’ll find the podcast on our website on Monday morning, and this week it’ll have some extra information about Dr. Weller’s research on sunlight, vitamin D and nitric oxide.
Joe
01:04:32-01:04:50
At peoplespharmacy.com you can sign up for our free online newsletter to get the latest news about important health stories. When you subscribe you can also have regular access to information about our weekly podcasts so you can find out ahead of time what topics we’ll be covering. In Durham, North Carolina, I’m Joe Graedon.
Terry
01:04:50-01:05:24
And I’m Terry Graedon. Thanks for listening. Please join us again next week. Thank you for listening to the People’s Pharmacy Podcast. It’s an honor and a pleasure to bring you our award-winning program week in and week out. But producing and distributing this show as a free podcast takes time and costs money.
Joe
01:05:25-01:05:34
If you like what we do and you’d like to help us continue to produce high-quality, independent healthcare journalism please consider chipping in.
Terry
01:05:35-01:05:39
All you have to do is go to peoplespharmacy.com/donate.
Joe
01:05:40-01:05:53
Whether it’s just one time or a monthly donation, you can be part of the team that makes this show possible. Thank you for your continued loyalty and support. We couldn’t make our show without you.
Citations
View all episodes
By Joe and Terry Graedon
4.5
966966 ratings
In this episode, our guest is a dermatologist who wants us to consider sunlight’s health benefits. That is a minority opinion among dermatologists. Dr. Richard Weller tells us why vitamin D is overrated and not the most important aspect of sun exposure.
At The People’s Pharmacy, we bring you the latest research-backed insights on health, even when they challenge established views. In this episode, Dr. Richard Weller highlights how moderate sunlight may offer unexpected health benefits while placing melanoma risk in context. This content is provided for informational and educational purposes only. Always consult a qualified healthcare provider before making changes to your sun exposure habits or medical care.
You could listen through your local public radio station or get the live stream at 7 am EDT on your computer or smart phone (wunc.org). Here is a link so you can find which stations carry our broadcast. If you can’t listen to the broadcast, you may wish to hear the podcast later. You can subscribe through your favorite podcast provider, download the mp3 using the link at the bottom of the page, or listen to the stream on this post starting on Sept. 1, 2025.
The Secrets of Sunlight’s Health Benefits:
Dermatologists generally advise us to stay out of the sun as much as possible. After all, excessive sun exposure causes skin aging and skin cancer, conditions for which people frequently consult them. However, even if we could all live inside, wear protective clothing and high SPF sunscreen whenever we ventured out, would that be wise?
According to our guest, Dr. Richard Weller, and his colleagues, “insufficient sun exposure has become a real public health problem” (International Journal of Environmental Research and Public Health, July 13, 2020). While this problem is more acute in Europe than the US, they still estimate that more than 300,000 Americans die each year due to inadequate sun on their skin. What is going on?
How Does Sunlight Affect Skin?
For decades, we have heard that the principal effect of sunlight on skin is the production of vitamin D. Therefore, the dermatologists have concluded, rather than take the risk of exposing skin to sunshine, why not just swallow vitamin D supplements?
The problem with that proposal is that it hasn’t worked very well. Many studies show that people with low levels of circulating vitamin D are more vulnerable to high blood pressure, atrial fibrillation, heart disease, diabetes and infections, among other problems.
However, people who take vitamin D supplements don’t always get the expected benefits. Perhaps vitamin D is a marker for sun exposure rather than the most important outcome.
Human Evolution and Skin Color:
Humans evolved in Africa, where dark skin is an advantage, offering protection from the most harmful effects of ultraviolet radiation. By about 60,000 years ago, people were migrating to other parts of the world. Yet analyses suggest that although they arrived in Europe by about 40,000 years ago, genes for pale skin didn’t become common until less than 10,000 years ago.
Anthropologists have hypothesized that pale skin is an adaptation to inadequate sunlight in northern regions. Because vitamin D is a well-recognized consequence of sunlight on skin, they have assumed that was the driver. Dr. Weller suggests that nitric oxide was (and still is) more important. He notes that the evolution of pale skin happens around the same time that people begin to cluster together in farming communities, where they are more likely to be exposed to infectious diseases.
Is Nitric Oxide the Source of Sunlight’s Health Benefits?
In 1996, Dr. Weller was the first scientist to find that human skin creates a compound called nitric oxide (NO) under sunlight. This compound is then absorbed into the skin, where it helps relax blood vessels and lower blood pressure. Here is a link to his TED talk on the topic.
This is where Dr. Weller’s approach differs from that of more conventional dermatologists. With proper caveats that the US is at much lower latitudes, in general, than most of Europe, he proposes that more sunlight, not less, could lower mortality rates. (Lower latitudes get more sunshine.) His analysis was just published in the prestigious Journal of Investigative Dermatology (August 2024).
The data underpinning this claim are from an analysis of the UK Biobank, a remarkable treasure trove of information. Dr. Weller and his colleagues have found that in the UK, people who get more sunlight are less likely to die within a specified time frame. We call that lower all-cause mortality.
You can read the research report here (Health & Place, Sept. 2024). It was discussed in this article in The Economist (Aug. 12, 2024).
This Week’s Guest:
Richard Weller, MD, FRCP(Ed), is Professor of Medical Dermatology at the University of Edinburgh. He holds the Personal Chair of Medical Dermatology in the Deanery of Clinical Sciences. He is also Honorary Consultant Dermatologist at NHS Lothian and Principal Investigator at the Centre for Inflammation Research.
Dr. Weller serves as Programme Director for the M Med Sci at the University of Edinburgh and is President of the Scottish Dermatology Society. He is the Clinical Lead for the Dermatology Speciality Group at NHS Research Scotland, the Global Health Academy and Edinburgh Imaging.
Listen to the Podcast:
The podcast of this program will be available Monday, Sept. 1, 2025, after broadcast on Aug. 30. You can stream the show from this site and download the podcast for free.
Learn More:
Dr. Weller kindly shared links to some research by his colleagues that he mentioned during the show.
Here is an article by Joel Gelfland showing the benefits of home phototherapy for psoriasis.
This article by Adewole Adamson presents evidence that dark skin is not susceptible to UV-induced melanoma.
Download the mp3 of the show, or listen to the podcast on Apple Podcasts or Spotify.
Transcript of Show 1397: The Surprising Secrets of Sunlight’s Health Benefits
A transcript of this show was created using automated speech-to-text software (AI-powered transcription), then carefully reviewed and edited for clarity. While we’ve done our best to ensure both readability and accuracy, please keep in mind that some mistakes may remain. This transcript is copyrighted material. All rights reserved. No part of this transcript may be reproduced, distributed, or transmitted in any form without prior written permission.
Joe
00:00-00:01
I’m Joe Graedon.
Terry
00:01-00:05
And I’m Terry Graedon. Welcome to this podcast of the People’s Pharmacy.
Joe
00:06-00:27
You can find previous podcasts and more information on a range of health topics at peoplespharmacy.com. Do you avoid the sun? We’ve all heard that we should wear sunscreen all the time and stay inside from 10 till 2. This is the People’s Pharmacy with Terry and Joe Graedon.
Terry
00:33-00:45
Are there hidden health benefits from sunlight? Is it all about vitamin D? Why don’t supplements protect people against heart disease, cancer, diabetes, or depression?
Joe
00:45-00:52
New research suggests that some sun exposure may be helpful. Our dermatologist guest has done fascinating research.
Dr. Richard Weller
00:53-01:04
We have showed in Britain that after accounting for confounding factors, other factors, the more sunlight people have, the longer they live.
Joe
01:04-01:10
Coming up on the People’s Pharmacy, the surprising secrets of sunlight’s health benefits.
Terry
01:14-02:31
In the People’s Pharmacy Health Headlines, following a Mediterranean-type diet may help lower the risk of dementia in vulnerable people. People who carry a gene called APOE4 are particularly susceptible to developing Alzheimer disease. But an analysis of the Nurses’ Health Study and the Health Professionals Follow-up study published in Nature Medicine shows that those who come closest to a Mediterranean eating plan are less likely to come down with Alzheimer’s disease. There were more than 4,000 women and nearly 1,500 men included in the analysis, which covered three decades of data. People with two ApoE4 genes lowered their risk by 35% if they followed a Mediterranean diet high in vegetables, fruits, whole grains, fish, and olive oil. The lead author, Dr. Yuxi Liu, told CNN, “Not only did following a baseline Mediterranean diet reduce the probability of developing dementia by 35% in people with two APOE-e4 genes, but higher adherence to the diet further reduced their risk.”
Joe
02:30-03:36
The anti-vax movement has been gaining momentum, but there’s growing evidence that the shingles vaccine offers benefit far beyond protection against shingles. Several studies have demonstrated that the shingles vaccine can reduce the risk for dementia. A new study published in the journal Clinical Infectious Diseases reports that the recombinant herpes zoster vaccine Shingrix can reduce the risk of heart attack, stroke, and herpes zoster ophthalmicus, a potentially vision-robbing eye infection. The researchers compared over 100,000 vaccinated patients to over 400,000 unvaccinated patients. The median age was 68 years old. The average follow-up was two and a half years. The investigators concluded that two doses of Shingrix vaccine “were effective in preventing herpes zoster ophthalmicus in adults over 50, and were associated with significantly reduced risk of hospitalized acute myocardial infarction and stroke compared to unvaccinated individuals.”
Terry
03:36-04:27
The FDA has just approved a new and far more general indication for evolocumab, known by its brand name Repatha. Back in 2015, the agency approved this powerful injectable medication for lowering LDL cholesterol. At first it was used primarily for patients at high risk who couldn’t tolerate statins, or who didn’t respond adequately to statins for lowering cholesterol. Then the use was expanded to cover people with cardiovascular disease. Now, doctors can prescribe this medicine for any adult at risk for heart attacks, strokes, unstable angina, or other cardiovascular complications. Occasionally, people react to evolocumab with angioedema, which can be life-threatening. Such individuals will not be able to use it.
Joe
04:28-06:18
At one time, x-rays were the only tool doctors had to see inside the body. Since then, MRIs and CT or CAT scans have become widely available. Computed tomography imaging is performed on over sixty million patients annually. That number has increased by over thirty percent since 2007. Such images can be extremely helpful in making a diagnosis, but there are risks that many patients may not realize. The name CAT scan sounds innocuous, but in fact it represents ionizing radiation similar to X-rays. An investigation published in JAMA Internal Medicine projected the number of future cancers due to this radiation exposure. The researchers used data from the University of California, San Francisco International CT Dose Registry and modeled the effects of the radiation. They estimated that approximately 103,000 cancers are likely to result from the 93 million scans conducted in 2023 on 60 million people. The risks are highest in children and adolescents, but many more adults undergo CT scans. The scientists conclude that if current practices persist, CT associated cancer could eventually account for 5% of all new cancer diagnoses annually. And that’s the health news from the People’s Pharmacy this week.
Joe
06:15-06:17
Welcome to the People’s Pharmacy. I’m Joe Graedon.
Terry
06:18-06:35
And I’m Terry Graedon. For decades we’ve been told to stay out of the sun, especially in the summertime. If we venture out, we need to be wearing protective clothing, including a hat and high-SPF sunscreen. If we’re good, we’ll never get a tan in the summer.
Joe
06:36-06:51
Dermatologists worry about sun exposure because ultraviolet radiation is damaging to the skin. It causes premature aging and is linked to various forms of skin cancer, including the most dangerous, melanoma.
Terry
06:52-06:57
But could sunlight be more complicated? Does it have hidden health benefits?
Joe
06:58-07:24
To learn more about this very controversial topic, we turn to Dr. Richard Weller. He is a professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology at the Deanery of Clinical Sciences. His research interests include eczema, psoriasis, and the effects of sunlight on human skin.
Terry
07:24-07:28
Welcome to the People’s Pharmacy, Dr. Richard Weller.
Dr. Richard Weller
07:29-07:32
Hello, it’s very nice to be talking to you today.
Joe
07:32-07:40
Dr. Weller, there’s a rumor that you are a dermatologist. Do I have that right?
Dr. Richard Weller
07:41-07:52
I am. I’m perhaps not a conventional dermatologist in some of my views, but those have really developed over the years as a consequence of my research.
Joe
07:53-08:43
Well, speaking of your research, it kind of contradicts what American dermatologists have come to believe, which is: If you could just live in a cave, that would be ideal because that way you would never be exposed to ultraviolet radiation. In other words, sunlight. And the only time you’re allowed to go out in the sun is if you have slathered on a high SPF sunscreen, 50 or above. And definitely avoid being outside between 10 and 2 because sun is your enemy. It’ll cause cancer, it’ll cause wrinkling, it’ll mess up your life.
Terry
08:42-08:43
You are exaggerating.
Joe
08:44-08:44
Of course.
Terry
08:44-08:46
But not by very much.
Joe
08:46-08:58
So you’ve kind of come up with a different perspective, Dr. Weller. Can you tell us a little bit about your time in Australia and why that started you down this path in part?
Dr. Richard Weller
08:59-10:30
Sure. I mean, I think you’re you’re pretty accurate about the American dermatology view to sunlight. And I think what I really want to say is we need a more nuanced view on sunlight. And of course, the second thing to say to you is that I’m speaking to you from Scotland, and people forget how much further north Europe is than Scotland [Scotland is than the US]. So you know, the further away you are from the equator, the less sunlight there is. And as an example, if you live in the cold woolly fringes of Maine or New England, you’re actually at the same latitude as the Côte d’Azur, as Cannes, right down on the Mediterranean coast of France. And if you live in Florida, you’re on the same latitude as the Sahara. So the amount of sunlight Americans are getting is way more than we North Europeans are getting. So I’m speaking to you with someone from Scotland and probably what I see is different from what my American colleagues see. Nonetheless, sunlight has significant health benefits, as my research and that of other colleagues around the world is now showing. There has to be more to the message we give than just ‘sunlight is bad’ because that’s becoming outdated. And that’s really the message I’d like to get across.
Terry
10:31-10:38
I wonder if you could summarize for us, Dr. Weller, what some of those benefits of sun exposure might be.
Joe
10:38-10:45
And in particular, can you tell us a bit about Australia and cardiovascular disease?
Dr. Richard Weller
10:46-11:46
Sure. So yeah, I mean so look, I I suppose a bit about my career. I’m an academic dermatologist. I’ve been a dermatologist for about 30 years. Before I became a dermatologist, I did an internal medicine training and as part of that I worked in Australia, in Northern Australia and Queensland for a year. And Australia is much sunnier than the UK. So in Cairns, where I was living- the UV index is seven or above every single day of the year. So in mid-winter, the UV index, which is a measure for the burning ability of the sunshine, hits about seven, you know, for an hour or so around midday, and it rises to fourteen in midsummer. So in Scotland last year, the UV index hit seven for ten minutes. It was just after lunchtime on the 24th of June, if you want to know exactly when.
Terry
11:47-11:47
Okay.
Dr. Richard Weller
11:48-13:58
And yet we are given sunlight protection advice copied directly from the historical Australian advice. Designed for white Australians, you know, Australians of North European heritage who’ve moved to somewhere hugely sunnier and that is inappropriate [in Scotland]. You know, skin color is an evolutionary adaptation to sunlight. So, you know, Homo sapiens, that’s us, we’re about 160, 200,000 years old as a species. Non-African humans are the descendants of people who left Africa about 60,000 years ago And what is interesting is those humans who’ve moved to high latitude, so Europe and China, modern China have independently evolved pale skin repeatedly on moving to low light environments. So the pale skin gene variants that we see in Europe, um SLC 45A2 in particular, arose about 8,000 years ago. Independently pale skin gene variants arose in humans who had moved to high latitude modern China. So skin color determines your response to sunlight. That’s that’s what it’s about. And what’s happened is repeatedly humans who’ve lived in low-light areas have there’s been an evolutionary fitness advantage to getting to to developing pale skin which allows you to get more of sunlight’s benefits. But at the same time, if you fly down to or go by convict ship from Britain to Australia you’re very suddenly moving to somewhere with way more sunlight than your skin um is adapted to manage. And that’s when you see the problems of skin cancer and and sunburn and so on. Texas is the same as Australia in that sense.
Terry
13:59-14:38
Now, Dr. Weller, as an anthropologist, I’m familiar with what I guess is uh the hypothesis that as you say, uh, pale skin is an evolutionary adaptation to not getting enough sunlight, and therefore when we expose our pale skin to the uh sunlight that we can get in uh you know, North Carolina or New Jersey or France or where have you, we’re able to make the vitamin D we need. Are there other considerations beyond vitamin D?
Dr. Richard Weller
14:39-17:39
Yes, very much so. And of course the key question is, you know, that there must be a benefit because it keeps occurring. What are those benefits? And I and I have to say straight off, I think the benefits of vitamin D are hugely overstated. Vitamin D is less important than we have thought for much of the last hundred years. So we look, it may have played a part in the development of pale skin. We know that people with darker skin need more sunlight to get the rise, same rise in vitamin D. But you know, we don’t in Britain nowadays see rickets or problems that associate with vitamin D deficiency in African, you know, British African communities, for instance. And actually, skin color doesn’t enormously affect vitamin D synthesis. A lot of my research about sunlight has been looking at cardiovascular disease. We find that sunlight lowers blood pressure independently of vitamin D. There’s a substance called nitric oxide, which my research has shown is stored in the skin, and when sunlight hits the skin, it releases that nitric oxide, the circulation where it dilates blood vessels and lowers your blood pressure. And that has really quite a big effect at population level. So again hit here in Britain The average blood pressure is six millimeters of mercury systolic lower in summer than winter. And that appears, that’s probably a nitric oxide effect. It’s definitely not a vitamin D effect. In terms of the evolutionary history of skin, that gets more interesting. My feeling is that heart disease, blood pressure, high blood pressure related disease like heart attacks and strokes is unlikely to have been a problem in evolutionary times. You know, chasing after woolly mammoths, running away from saber toothed tigers. Pre-the invention of cigarettes, I think it is unlikely that heart disease was a big problem. What I’m looking at now with my research is we wonder if infection may have played a role. Because what’s fascinating is humans have been in Europe for about 40,000 years, been in Asia for about 60,000 years. And yet the development of those pale skin gene variants in Europe only starts about eight thousand years ago, and initially the that the that the white skin gene variants arise in in the fertile crescent, you know. Anatolia. And those white skin gene variants arise in East Asia around eleven thousand years ago. And it it arises at the time when we make the shift from being hunter-gatherers to farmers.
Terry
17:40-17:57
You’re listening to Dr. Richard Weller, Professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology in the Deanery of Clinical Sciences and participates in the Center for Inflammation Research.
Joe
17:58-18:07
After the break, we’ll find out more about how farming might have contributed to evolutionary changes in skin color.
Terry
18:07-18:11
Dr. Weller offers us a summary of the health benefits sunlight can provide.
Joe
18:12-18:16
Lack of sun exposure is actually associated with some health problems.
Terry
18:17-18:22
Studies on sunshine are mostly being done in the UK and Europe, not in the US.
Joe
18:22-18:31
Dermatologists sometimes suggest we could just take vitamin D supplements to make up for lack of sunlight. Why isn’t that adequate?
Terry
19:45-19:48
Welcome back to the People’s Pharmacy. I’m Terry Graedon.
Joe
19:49-20:12
And I’m Joe Graedon.
Terry
20:13-20:28
Why do people who live in northern latitudes tend to have pale skin? Presumably, there’s some evolutionary advantage. Anthropologists have suggested that pale skin is better at making vitamin D when sunlight is scarce.
Joe
20:29-20:49
Many dermatologists encourage people to avoid the sun as much as possible. To make up for the possible lack of vitamin D, they suggest taking vitamin D supplements. But research on vitamin D pills or injections has been strangely disappointing. Why would that be?
Terry
20:49-21:18
Does sun exposure have any other physiological effects beyond triggering vitamin D synthesis? Dermatologist Steve Feldman of Wake Forest University has found that Ultraviolet exposure can boost psychological mood, making people feel more relaxed. He also found it can help people with chronic pain such as fibromyalgia feel more comfortable. Our guest today has also been studying the impact of sunlight on skin for years.
Joe
21:18-21:40
We’re talking with Dr. Richard Weller. He’s professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology at the Deanery of Clinical Sciences. His research interests include eczema, psoriasis, and the effects of sunlight on human skin.
Terry
21:41-21:55
Dr. Weller, how would the rise of uh domestication and farming tie in to a change in skin color? How does that make sense?
Dr. Richard Weller
21:56-24:58
Yeah well this is the really interesting thing because being at high latitude, low light, by itself has not driven a move to pale skin. Because humans have been 40,000, you know, I mean if you go to the Dordogne in France, the amazing cave art, you know, the wonderful pictures of woolly mammoths and so on and ancient animals on the roofs of the caves, dates back twenty thousand years ago, when actually the people who painted that were dark-skinned. So this this move to, so it’s not just being at high latitude, because most of the time that Europe’s been inhabited, it’s been inhabited by dark-skinned people. And it’s not just being a farmer, because farming has arisen independently. I mean farming arose independently in what’s now Mexico, maize; it’s arisen independently in India; it’s arisen independently in Papua New Guinea. So either by themselves does not precipitate that move to pale skin. It’s when the two come together. It’s when you’re a farmer in a low light environment that pale skin arises. So that sort of information sets the question. It doesn’t give the answer.
It is possible that part of it’s dietary, you know, we know that that Neolithic transition from being a hunter-gatherer to a farmer actually led to a poorer diet. shorter people, probably higher infant mortality. You know, it wasn’t all milk and honey when we moved to being farmers. So it could be a dietary factor, it could be related to vitamin D. Sorry, vitamin D for an American audience. My but I have to say my feeling is it may be or it is likely to be infection. Because the thing that really happens when you make that Neolithic transition shift is that’s the advent of infectious disease. Because most infectious disease comes from animals, what we call zoonotic. You know, COVID comes from bats, TB comes from cows, influenza comes, you know, most infectious disease comes from animals. And when you’re a farmer, you’re living with animals. And the other thing, of course, is when you’re a farmer, you’re living in communities, you’re living in villages close to other people, rather than being hunter-gatherer bands dispersed across the landscape. And so most infectious disease arises from that time, we think. And I suspect that there are UV-driven processes which reduce infection. And that’s what we’re really looking at at the moment. And the point about skin color is it mediates your response to sunlight. It’s not pale skin itself that prevents you get infections. It’s the fact that pale skin allows you to maximize the biological effects of sunlight.
Joe
24:58-26:23
Dr. Weller, I’d like to go back and sort of summarize, if you don’t mind, all of the benefits of exposure to sunlight, because as I introduced a little bit tongue in cheek, American dermatologists believe that that sunlight is problematic, that it will cause all kinds of problems, and that we need to use these high SPF sunscreens or better yet stay out of the sun completely. So you’ve already suggested that blood pressure is affected by exposure to sunlight. You’re now alluding to the possibility that our immune system may be enhanced by sunlight, but there are a whole lot of other conditions as well. I think about inflammatory conditions like arthritis. I think about autoimmune conditions like eczema. I think about kidney disease and osteoporosis and diabetes. So can you just sort of summarize all of the potential health problems associated with lack of exposure to sunlight? How people in Australia may be quite different from people in Greenland, in terms of their risk of heart disease? So give us that big perspective.
Dr. Richard Weller
26:23-32:25
Yeah, look, I’m delighted to and of course I’ve start I’ve jumped straight into where my my current research is because that’s really exciting. So so sunlight’s got ups and downs, got a good side and a bad side. So look with my dermatologist hat on broad brimmed shady hat. Sunlight is a risk factor for skin cancer and it is a risk and it leads to skin aging. So that’s the kind of downside. But it’s also got an upside.
There is a wonderful means about looking at how do these risks and benefits weigh out. And that’s what we call all-cause mortality: death from any cause. And that gives you very robustly a summation of those two factors, the pluses and the minus. So we have a paper coming out actually next week. We’re just uh arranging uh stuff with the journal at the moment. which touches on this subject, but the first person to look at it uh was a colleague and friend of mine, Pelle Lindqvist, who is an obstetrician in Sweden. And he did a wonderful study called the Melanoma or the Melanoma in Southern Sweden study. So this was set up in 1990. It was designed, as the name suggests, to find what causes melanoma, and how does it kill people. And 30,000 Swedish women, 30,000 middle-aged Swedish women in southern Sweden. So that that at the time was a quarter of the population of southern Swedish and middle-aged women were recruited in 1990 and they were asked a series of questions about how much sunlight they got. But they were also asked an extensive range of other questions asking about lifestyle factors, education, income, health, you know, other smoking habits, medical conditions. So the baseline information was taken, they were then followed for 25 years, and then the investigators went back to find out what had happened to them. And the first thing to say is that those had most sunlight were more likely to have had a case of melanoma. But Pelle’s interest and my interest is what about the deaths? I’m not interested in cases of the diseases. I’m interested in death from any cause. And there, much to the surprise of the dermatologists who set the study up, the direction was in the opposite direction to melanoma cases. They found that the women who had the most sunlight after correcting for all of these other factors, you know, income, education, smoking, etc. , etc. , those that had the most sunlight were half as likely to be dead. 25 years after the study started, as those who had the least sunlight.
So that’s the first study. We have just done a much larger study looking at the UK Biobank. So the UK Biobank, uh half a million middle aged people in Britain were recruited (I was one of them) and examined in great depth over about it took about four years to recruit the whole cohort, um, all around Britain. And every subject went up to an investigation center where there was about three hours of questionnaires, investigations, measurements, you know, mass of information taken. And that was back in 2000 and uh, anyway, about about 20 years ago. And those people have followed up long term. And we have gone into that database and we’ve taken 400,000 people from that, and we have looked at measures of sunlight exposure. So the measures of sunlight exposure we have used have been how far south people live in Britain, because the further south you live, the more sunlight you get. And our other measure actually was people who use sun beds, not so much because of the sun beds themselves as because behaviorally we know that people that use sun beds sunbathe more, actively seek the sun more. Now, we then had to correct for all the confounders. You know, sun bed users are younger, more female, less educated, more likely to come from Manchester, etc etc and we had to correct for the same factors the further south people lived. And what we find is that the more sunlight people get the longer they live. They have a reduced all-cause mortality. They have a reduced cancer mortality.
Melanoma is an interesting one. There was an increase in diagnoses of melanoma in those that got more sun, but no increase in mortality from melanoma and pretty much all the other cancers had a reduced mortality. And cardiovascular mortality was also greatly reduced. So just as Pelle showed in Sweden, we have showed in Britain that after accounting for confounding factors, other factors, the more sunlight people have the longer they live. Now one big caveat I’m gonna throw in for your audience is these are North European studies. And our sunlight levels here are much lower than your levels in America. You know, white skin has developed in Europe because we don’t have much sunlight. And this data applies here. I’m not sure how much it’s going to apply in America. And of course the studies haven’t been done because all people have thought about sunlight is oh gosh, it’s dangerous, it’s bad. But really interesting. Certainly for us in northern Europe, I think a really important, really important finding.
Terry
32:26-32:46
So you’re not aware of any American colleagues who are doing anything similar? Of course, we don’t have a resource like the UK Biobank, which is an extraordinary resource of a huge amount of information, I don’t believe anything of that sort has been collected in the US.
Dr. Richard Weller
32:47-35:46
No, I mean these studies can’t really be done in America. I mean most of these studies come out of Scandinavia and Britain because we have universal health systems. So if you get sick or have disease or die, you know, all our data are collected centrally. America has such a bizarre health system and it’s so fractured and broken up into small things, it’s not really possible to do there. What America has been very good at at doing though is things like clinical trials and I need to mention vitamin D, vitamin D. Because the other thing to say here is vitamin D’s benefits have been vastly overplayed. Now we know that so sunlight is responsible for making vitamin D. Vitamin D has some important benefits, rickets, you know, it prevents rickets. And we know that when you measure vitamin D People with higher measured vitamin D levels are healthier in almost every way you can mention. Less heart disease, less strokes, less multiple sclerosis, less diabetes, etc. , etc., etc. The problem is when you give vitamin D, there are you know, it prevents rickets, which we’ve known for a hundred years. And there is an enormous rearguard action going on by the vitamin D industry saying, oh, well, what about this? What about this? What about this? Um and the vitamin D industry, I mean it’s a it’s worth, I think, it’s about two billion dollars a year. It is a huge industry.
The biggest study of all on vitamin D supplementation was run in America. You’re fantastic at this, you know, NIH comes in with its funding. And there was a study called the Vital Study, run by Joanne Manson 25,000 Americans, 25,000 adult Americans were recruited. Half of them were given vitamin D supplements for five years and half of them were given a placebo, a sham control. And at the end of five years and really the study has now ended, but the patients are being followed up. And what it confirms, and it confirms the findings from lots of other smaller studies, is vitamin D has absolutely no effect on heart disease, on strokes. Probably doesn’t do much for cancers. Um, you know, the results came back negative, negative, negative. And there was an editorial in the New England Journal of Medicine 18 months ago. summarizing all this saying stop taking vitamin D supplements. You know, unless you are one of those very few people with incredibly low levels of vitamin D, it’s not doing anything. And people come up saying I’ve got vitamin D deficiency. And you say, what do you mean? Oh, I had a blood test. Doctors do not treat blood tests. We treat disease. A blood test is not a disease. You know, you wouldn’t know if you hadn’t had it done. But there is a huge industry out there pushing this.
Terry
35:46-36:11
So, Dr. Weller, we actually have spoken with uh Dr. Manson and with one of her colleagues, and there was one area in which the VITAL study showed some benefit for vitamin D supplements and that was it reduced the likelihood that someone would be diagnosed with a new autoimmune condition. So you know…
Dr. Richard Weller
36:12-37:16
Yes, I look I’m I am not saying vitamin D is absolutely irrelevant. I think we know about rickets, the autoimmune condition is is interesting. But the vast array of benefits that have been claimed for vitamin D are not held up by that amazing study. So what is interesting is that sunlight acts in multiple ways. Now a bit of it is vitamin D. but there’s so many other areas by vitamin D independent mechanisms. And that’s really exciting. And the problem is our focus has been so much exclusively on vitamin D. We have just ignored this. We’ve said, oh yeah, I know the fact that people are healthier. It’s vitamin D. Live in a cave, take vitamin D supplements. And those vitamin D supplements only account for some of sunlight’s benefits. And we need to move on and look for what the other mechanisms are.
Terry
37:17-37:36
You’re listening to Dr. Richard Weller, Professor at the University of Edinburgh College of Medicine and Veterinary Medicine. He holds the personal chair of medical dermatology in the Deanery of Clinical Sciences and participates in the Center for Inflammation Research.
Joe
37:36-37:42
After the break: Why can’t we compensate for sun exposure by taking vitamin D supplements?
Terry
37:43-37:48
Well, could it be that maybe, as doctor Weller says, vitamin D is just a marker for sun exposure?
Joe
37:49-37:51
What exactly does that mean, a marker?
Terry
37:52-37:58
Well, it means we can measure vitamin D, and there are things we can’t measure. We don’t measure nitric oxide that well.
Joe
37:59-38:02
Well, what’s a reasonable amount of sun exposure?
Terry
38:02-38:10
We’ll also find out more about Dr. Weller’s research on how sunlight triggers nitric oxide formation and how that affects us.
Joe
38:10-38:15
What does nitric oxide do for the immune system?
Terry
38:32-38:37
You’re listening to the People’s Pharmacy with Joe and Terry Graedon.
Joe
38:45-38:48
Welcome back to the People’s Pharmacy. I’m Joe Graedon.
Terry
38:48-39:13
And I’m Terry Graedon,
Joe
39:13-39:34
Today on the People’s Pharmacy, we are exploring the controversial concept that some sun exposure might have hidden health benefits. Of course, we want to emphasize that no one should get burned by the sun. In addition to being painful, sunburn creates the risk for melanomas.
Terry
39:34-40:04
To find out more about phototherapy and how ultraviolet light acts to produce nitric oxide in the skin, we turn back to our conversation with Dr. Richard Weller. He’s a professor at the University of Edinburgh College of Medicine and Veterinary Medicine, and holds the personal chair of medical dermatology in the Deanery of Clinical Sciences. He also participates in the Center for Inflammation Research.
Joe
40:05-40:59
So Dr. Weller, you have just put into perspective the fact that vitamin D is not the answer to lack of sun exposure. And I want to just quickly go back and summarize all of the benefits of sunlight And what happens when you don’t get exposed to sunlight? And you’ve alluded to things like hypertension, cardiovascular disease, cancer. You’ve mentioned kidneys, you’ve mentioned diabetes. What about autoimmune conditions such as multiple sclerosis? What about eczema, which I believe is something that you have a lot of experience with? Tell us why sunlight is so important for our body’s health.
Dr. Richard Weller
40:59-45:54
Yeah, great question, thank you. And I’m delighted you bring multiple sclerosis up. So multiple sclerosis It is the classic sunlight deprivation disease. So, you know, even when I was at medical school, and that was a frighteningly long time ago, We knew that MS was a disease that was most common in people who grew up in areas without much sunlight. So I’m in Scotland and we have the highest rates of MS in the world here. And in fact, the highest of the highest is the Orkney Islands, which are just off the north of Scotland. Beautiful place. But something like I think about one in eight hundred people there has MS. Incredibly common. So a colleague and friend of mine, Prue Hart in Australia. And so and again, the classic story. people with low measured vitamin D levels are more likely to get MS. You give vitamin D you know, kinda iffy you know, the the observational effect is huge. This huge great relationship measured vitamin D. You give vitamin D supplements, not very much happens. So it’s got to be more than just the vitamin D.
And I might say there’s a super company in America, Cytokines, led by a wonderful guy John McMahon, which is setting up a phototherapy study of MS in the United States. So there’s really good preliminary work done in Australia where people who when they had their very first diagnosis of MS, their very first demyelinating episode, were randomized either to get phototherapy, the kind of stuff that dermatologists use on their offices, well established, incredibly safe treatments, They were randomized either to get phototherapy or to get a control. And there was a really strong move towards a reduction in progress of MS, and a really marked improvement in the the biomarkers that are a good indicator of whether people are going to progress or not. Really exciting. The big problem, of course, was it was done in Australia. So your control group not getting phototherapy, well, they’re still in Australia under quite a bit of sunlight. And of course the other reason there isn’t much MS in Australia. It’s a very sunny country. There’s masses in Britain. So John McMahon and his company are leading this to me really exciting trial of phototherapy for MS in America. And I am watching with huge, I mean just really exciting, because here is a disease which should absolutely go along with phototherapy. And also the narrowband UVB phototherapy that we dermatologists use to treat eczema and psoriasis. has been around for twenty or thirty years incredibly safe. I think utterly over-medicalized. I mean It’s been around for 20 or 30 years. There’s no signal for skin cancer being found in Britain for people having UVB phototherapy. So it’s sunlight. We don’t see a skin cancer signal. And yet you have to see a doctor. You have to see a dermatologist to get it. Um, I think it should be used far more widely.
Great American dermatologist called Joel Gelfland, again, fantastic guy. Has just done a wonderful trial of home phototherapy, people with phototherapy lamps at home. And he’s compared how well they do to people who go to their dermatologist office to get phototherapy. And he finds people with their lamps at home do amazingly well. They do as well in terms of reduction in their psoriasis as patients receiving these biologic treatments, these incredibly expensive but highly effective monoclonal antibody treatments. Well actually phototherapy, Joel showed, is as good. And I might say a fraction of the cost and, you know, I mean basically it’s it’s sunlight in a box. And I think we greatly underuse it. And we underuse it because we’ve demonized sunlight. So here is a sunlight-based treatment. And of course, that really threw dermatologists in the quandary. Hang on. We run around saying Don’t go in the sun. And then suddenly we’ve got a treatment which is based on ultraviolet. What do we do? What are oh no, we’re gonna surround it with caveats and cautions and warning signs. I think we’ve gone completely overboard with that and it means we are not using this safe and effective and clean treatment nearly as much as we should be. So I’m delighted that people like Joel Gelflands as a dermatologist and John McMahon with his MS studies is really restoring, you know, kind of rejuvenating this wonderful and underused treatment modality.
Joe
45:54-47:02
Dr. Weller, I want to come back to your research with nitric oxide, because I’ve been fascinated by nitric oxide for decades. But first, you know, w we’ve been talking about sunlight exposure, and for the most part Americans have a kind of love-hate relationship with the sun. They want to go out to the beaches, they wanna play outside, they wanna be golfing and playing tennis and going for hikes. But they wouldn’t dare go out without their SPF 50 or 100. I’m just wondering, can you give us some practical guidelines about how we can expose our skin to sunlight for a quote unquote reasonable or safe amount of time that won’t do damage, that won’t burn our skin and lead to wrinkling and squamous or basal cell carcinomas. How do we use the sun without getting into the sunbox that you were talking about a moment ago in in a safe way?
Dr. Richard Weller
47:02-48:45
Yeah, I mean a really good question. I mean the really key thing is to avoid sunburn and particularly for children to avoid sunburn because it’s sunburn particularly in children which is the major risk factor for melanoma, the serious skin cancer. Sunlight is photoaging. Sunlight is a risk factor for skin cancer. And you know, non-melanoma with skin cancers in particular, the more sunlight you get, the greater your risk. Look, I uh you know I have a kind of conflict of interest in here because I have, I’ve developed a a a compound you can add to sunscreen that will release nitric oxide in the sunscreen. You know, it’s it’s sort of in development. We’d love to get it out there. I I think sunscreens could be better than they are. I mean at the moment sunscreens are all about blocking sunlight, and blocking the sunlight will reduce the aging, it will reduce the burning, it will reduce the cancer. My concern is it’s also going to block the good things. I think sunscreens could be better than they are. It certainly my, in Britain I am pretty quite relaxed about sunscreen use because we live in a much less sunny place than it than America. Um in America you do have an awful lot of sunlight. Now I suppose what I’m going to say is more research is needed. I think sunscreens could be better. I think we haven’t looked hard enough at the benefits of sunlight and how much sunlight is required to get them to be able to give a really robust answer. And the reason we haven’t done that is because we’ve purely been focused on sunlight is bad, vitamin D will make up for the absence of it. And clearly the story is much more nuanced and complex than that.
Joe
48:46-49:07
Well, even if you are unwilling to make a recommendation because there’s a lack of science. What would be a reasonable amount of sun exposure, and at what time should we contemplate that sun exposure if we want to avoid sunburn and some of those damages you mentioned?
Dr. Richard Weller
49:07-51:42
Well if you live in Florida or Texas you’re gonna need some protection. You’re living in an African latitude, and if you’ve got white skin, you’ve got you I think you’ve just got to be protecting your skin a great deal out around the middle of the day. If you’re farther north, you know, it gets less of an issue, but you’re still in a very sunny climate I think Americans do need more sun protection than Europeans because you live so far south. And of course the other thing is skin color. Because um so really I work in Ethiopia a lot, although sadly with the political situation there, uh not for the last three or four years. So UV-induced melanoma really does not occur in dark-skinned people. Jay Adamson, a wonderful dermatologist, American dermatologist in Texas, has really shown that UV-induced melanoma does not occur in African Americans. When I work in Ethiopia, we do not see UV-induced melanoma. On at two and a half thousand meters altitude, eight thousand feet, in the tropics in Ethiopia. Incredibly sunny is the point. Dark-skinned Ethiopians do not get UV-induced melanoma. They get these rare subtypes of melanoma, not related to sunlight, but but skin color really determines your risks of of skin cancer. And I am concerned by the way that the American Academy of Dermatology regards all skin types as the same when it comes to sun protection Because certainly the work that we have done uh in America. So we looked at how sunlight lowers blood pressure in America, a big study on three hundred and thirty thousand Americans. And we showed that African Americans need more sunlight to lower their blood pressure than white Americans. So just as skin color determines your risks of getting skin cancer, It also determines how much UV you need to get the benefits of sunlight. You know, skin color is all about response to UV. And I am concerned that by putting out the same message to everyone of every skin color, that’s not wise because that risk-benefit ratio for sunlight is absolutely determined by your by your skin color. And it needs to be a different message dependent on your skin color.
Joe
51:42-51:56
Dr. Weller, we just have a couple of minutes left. I wonder if you could briefly summarize your research with nitric oxide and why it’s so incredibly important for so many physiologic functions.
Dr. Richard Weller
51:56-53:20
Yeah. Well the biggest killer in the world today is heart disease. So half, basically half of deaths in the world are caused by high blood pressure-related diseases, heart attacks and strokes. Sunlight lowers blood pressure and with it the risk of having a stroke or a heart attack. And the mechanism by which it does it is release of nitric oxide from the skin into the circulation. Hugely important. If you’re a male in Scotland, you are 30% more likely to drop dead of any cause in a week in December than a week in July. I’m pretty mellow at the moment, It’s July, It’s a good time of year. I’ll get through to the end of the week. I start getting a little nervous as the year gets later. And a lot of that is driven by nitric oxide from the skin and its effects on the cardiovascular system. So it’s not sunlight has benefits as well as risks. Those benefits are not just vitamin D. There’s other mechanisms. The mechanisms include importantly for cardiovascular disease, nitric oxide, but also I suspect other mechanisms that really just started to look at, like immune function in particular. So I really think we need to be reconsidering our approach to sunlight in a more balanced way, considering benefits and not just risks.
Joe
53:21-53:47
And Dr. Weller, in the one minute we have left, the role of sunlight and perhaps nitric oxide on the immune system, because goodness knows, we have certainly learned a lot from COVID-19 and the pandemic. A lot of people would prefer to reduce their risk from infection. How does sunlight help there?
Dr. Richard Weller
53:47-55:33
So well so interesting. So, so we looked at so we um at at the same time as, uh as a rival group in Harvard were looking at the effects of sunlight on COVID mortality. And we found in the very first three months of the pandemic that the sunnier it was after accounting for other factors, the less deaths there were from uh COVID. And that the Harvard group showed that the more sunlight there was, the less growth in cases. Now that’s observational studies, but we uh colleagues in America ran a pilot study in Louisiana giving phototherapy or, or a control to patients admitted to hospital with COVID. And it was a small study, only fifteen in each group, but they found a trend to reduce deaths in the sunlight group. And the third bit of evidence is people with high measured levels of vitamin D were less likely to get COVID or die of it, but multiple trials giving people vitamin D supplements, it had no effect. The usual story, measured vitamin D is a marker for sunlight exposure, not necessarily causative. So look, so I think there’s some really interesting data there suggesting that sunlight is driving processes which we’re now looking at that reduce your risk um of death from COVID. And that may apply to other infectious diseases, but the work needs to be done. And I suspect in evolutionary terms, that’s what has driven this move to pale skin in humans who move to low light areas.
Joe
55:33-56:04
So, Dr. Weller, you’ve described the benefits of sunlight as being more than just vitamin D.
Dr. Richard Weller
55:42-55:43
Yep.
Joe
55:43-56:04
That nitric oxide is also a critical factor, and it’s manufactured in the skin and then circulates in the bloodstream and lowers blood pressure and probably has a lot of other benefits as well. What else is going on? Do we know what sunlight exposure does beyond vitamin D and nitric oxide?
Dr. Richard Weller
56:04-59:08
Yeah, uh well I, I strongly suspect it’s having effects on the immune system and and in fact we’ve got f Pretty good evidence showing that. And that’s what I’m actually looking at at the moment with my current PhD student. So we’re so a really good early study in this area which we’re building on now by a chap called Dopico in Cambridge. Came to I think into Edinburgh actually. And he did one of these studies where you use other people’s data um very well. And they looked at um gene expression patterns in blood. Now what they did was they used about eight studies where people had had blood, and the studies have been done for various reasons. Everybody had their blood taken throughout the year during these studies, and the gene expression pattern, what genes were turned on and off in the whole blood, um, was looked at. And what Dopico and colleagues did was they looked, they analyzed the gene expression in these data sets by the month of the year in which the blood was taken. The studies were done for different reasons, but they happened to run over 12 months. And so he went in and thought, gosh, I’ll just analyze it by month of the year. And what he showed was that 30% of all the genes in your blood, you know, which are uh immune genes are very important there, show seasonal variation. So there is a huge uh seasonal variation, possibly I would imagine sparked off by UV, uh which occurs in immune cells. And broadly what he found was that inflammatory genes were turned on in winter and anti-inflammatory genes in summer. And the the, they suggest that maybe, you know, infectious disease flies around in winter. Maybe your body turns up the immune system to be able to jump on infectious disease. That was the hypothesis. So there’s now a technique called single cell RNA sequencing where you can look at every single individual cell, and so you can take, draw blood, you can look at ten thousand different cells, and you can look at every single gene turned on in every single cell. So the experiments I’m doing at the moment we do in winter. We take healthy volunteers. We load them up with vitamin D at the beginning, so they’re full of vitamin D at the start. Take their blood, look at all of their gene expression pattern, we then give them two weeks of daily solar-simulated UV, as if they were on in the Mediterranean, and we then repeat it. And we’re early days, don’t want to talk about the results yet, but we’re getting very interesting effects on gene expression patterns in in immune genes, T cell genes in particular. So it looks as if sunlight has significant effects on the immune system. And we’re really we’ll see where it takes us, but but really exciting stuff.
Joe
59:08-59:53
Dr. Weller, if we were to dial back, what, 100, maybe 150 years to a day when tuberculosis was rampant and a terrible killer around the world. There were sanatoriums where people would go and they were often exposed to sunlight. Even in the winter, they would take people outside, bundle them up and exposed them to the sun, they somehow thought that exposure to sunlight could help people dealing with tuberculosis recover or at the very least survive better. Did they know something we didn’t know?
Dr. Richard Weller
59:53-01:02:34
Yeah, I mean it’s really interesting and and I think sadly they never did, they had not yet invented robust, placebo-controlled clinical trials as we would understand them. But they weren’t fools. And of course, places like Davos, now an expensive ski resort and uh financial center. Davos was set up initially as a heliotherapy center, a center where people would go to get the sunlight for their tuberculosis. I I gave the opening address at the meeting of the Swiss the annual meeting of the Swiss Dermatology Association last year. And I pointed out and I was talking about the work we’ve been discussing today, and I pointed out to them that had I been there a hundred years ago, I would have been going as a disciple of the great Rollier, you know, the Swiss doctors who developed heliotherapy to treat tuberculosis. And instead, here I was a hundred years later, coming along to remind them of what they’d done previously. So absolutely, you know, we had it, you had it in America, we had it here in Britain. That was before antibiotics, the treatment for tuberculosis. And of course, and then for tuberculosis of the skin, a chap called Finsen in Denmark, developed ultraviolet lamp treatment for treatment of lupus vulgaris, tuberculosis of the skin. And he actually got the Nobel Prize for Medicine for this in I think it was 1904, really one of the very early Nobel Prizes for Medicine. So there is actually a history of UV having been used to treat infectious disease. And certainly since then we’ve had antibiotics and vaccines and we’ve had sewers and we’ve had clean airs, you know, we’ve had all of these measures that have reduced infectious disease death now. You know, the miracle of vaccination has basically eradicated infectious disease from our day-to-day life. So COVID was, I mean it was very tragic. It was also scientifically very interesting because suddenly you had a new infectious disease against which we had none of our usual defenses. You know, before the vaccines came, it was us and the virus. And you began to be able to see what happens to populations with a new virus. And it certainly looks as if those that had more sunlight had less deaths from COVID. And that for me was really very interesting. What the mechanisms are, we don’t yet know, and that’s what we’re looking for now.
Terry
01:02:34-01:02:41
Dr. Richard Weller, thank you so much for talking with us on the People’s Pharmacy today.
Dr. Richard Weller
01:02:41-01:02:44
Well thank you. I’ve enjoyed the conversation.
Joe
01:02:44-01:03:15
You’ve been listening to Dr. Richard Weller, professor at the University of Edinburgh, College of Medicine, and Veterinary Medicine. He holds the personal chair of medical dermatology in the Deanery of Clinical Sciences and participates in the Center for Inflammation Research. The show notes for today’s show have a link to the recent article in The Economist about his research and a link to his paper in the Journal of Investigative Dermatology.
Terry
01:03:15-01:03:26
Lynn Siegel produced today’s show. Al Wodarski engineered. Dave Graedon edits our interviews. B. J. Leiderman composed our theme music.
Joe
01:03:26-01:03:32
This show is a co-production of North Carolina Public Radio, WUNC, with The People’s Pharmacy.
Joe
01:03:57-01:04:12
Today’s show is number 1397. You can find it online at peoplespharmacy.com. That’s where you can share your comments about today’s show. You can also reach us through email radio at peoplespharmacy.com.
Terry
01:04:12-01:04:32
Our interviews are available through your favorite podcast provider, and now you can find them on YouTube as well. You’ll find the podcast on our website on Monday morning, and this week it’ll have some extra information about Dr. Weller’s research on sunlight, vitamin D and nitric oxide.
Joe
01:04:32-01:04:50
At peoplespharmacy.com you can sign up for our free online newsletter to get the latest news about important health stories. When you subscribe you can also have regular access to information about our weekly podcasts so you can find out ahead of time what topics we’ll be covering. In Durham, North Carolina, I’m Joe Graedon.
Terry
01:04:50-01:05:24
And I’m Terry Graedon. Thanks for listening. Please join us again next week. Thank you for listening to the People’s Pharmacy Podcast. It’s an honor and a pleasure to bring you our award-winning program week in and week out. But producing and distributing this show as a free podcast takes time and costs money.
Joe
01:05:25-01:05:34
If you like what we do and you’d like to help us continue to produce high-quality, independent healthcare journalism please consider chipping in.
Terry
01:05:35-01:05:39
All you have to do is go to peoplespharmacy.com/donate.
Joe
01:05:40-01:05:53
Whether it’s just one time or a monthly donation, you can be part of the team that makes this show possible. Thank you for your continued loyalty and support. We couldn’t make our show without you.
Citations
More shows like The People's Pharmacy
View all
Science Friday
6,333 Listeners
The Splendid Table: Conversations & Recipes For Curious Cooks & Eaters
3,065 Listeners
A Way with Words - language, linguistics, and callers from all over
2,284 Listeners
KERA's Think
934 Listeners
On Point with Meghna Chakrabarti | Podcast
3,933 Listeners
Radiolab
43,943 Listeners
Fresh Air
38,479 Listeners
The Moth
27,285 Listeners
MARGARET ROACH A WAY TO GARDEN
680 Listeners
To The Best Of Our Knowledge
945 Listeners
TED Radio Hour
21,947 Listeners
Hidden Brain
43,713 Listeners
Christopher Kimball’s Milk Street Radio
2,986 Listeners
1A
4,653 Listeners
Throughline
16,242 Listeners