This episode is one of our Premium-exclusive AMA (ask me anything) episodes, where we answer questions submitted by Premium subscribers.

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Full List of Questions:

1. [01:50] How should one interpret the systematic reviews done by Hooper et al that report no association between modification or reduction of saturated fat intake with cardiovascular mortality, total mortality, non-fatal MI?
2. [22.10] Given most people don’t meet them, are public health targets for fruit and vegetables too high?
3. [29.10] What is the role of homocysteine in heart disese? Is it causal?
4. [40:45] Monounsaturated Fat: Good, Bad or Indifferent?
5. [50:13] Is there evidence to suggest an upper limit for BMI, where even individuals with a ‘healthy’ body composition would be at elevated risk?
6. [59:32] Where does the current research stand on the impact of diet on brain health?
7. [01:08:48] Based on recent findings, do we have to throw out previous research on diet’s impact on the gut microbiome?

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About This Episode:

Navigating the intricate landscape of sports nutrition is one that constantly evolves and challenges our understanding of optimal athletic performance.

The delicate balance between advancing research and ensuring practical applicability in the high-speed realm of sports nutrition is a perpetual struggle.

Decision-making is difficult, especially when faced with a scarcity of evidence. It’s a challenge that resonates with many professionals in the field, prompting reflections on the art of making informed choices in the absence of conclusive data.

In this episode, Dr. Andy Kasper, PhD shares his experiences and research in the field of elite sports nutrition.

Dr. Kasper, a PhD in Nutrition and Physiology from Liverpool John Moores University, currently spearheads the Performance Nutrition department at Newcastle United Football Club. His illustrious career spans across elite football, rugby union, and rugby league, with notable stints at clubs like Chelsea, Fulham, Derby, England Rugby Union, Sale Sharks, London Irish, and Wasps, to name a few.

A prolific contributor to academic publications, Dr. Kasper’s insights have not only shaped the scientific landscape but have also directly influenced the nutritional strategies employed by top-tier athletes.

Our conversation will traverse a myriad of topics, from the transformative changes witnessed in sports nutrition to invaluable advice for practitioners navigating this intricate terrain.

We’ll also delve into the delicate balance between advancing research and ensuring practical applicability in the fast-paced world of sports nutrition. Dr. Kasper will shed light on the Paper-to-Podium Matrix, a concept that bridges the gap between scientific discoveries and their real-world implementation in the pursuit of athletic excellence.

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About This Episode:

The Oslo Diet-Heart Study was one of the earliest randomized controlled trials to explore the relationship between diet and heart disease. It aimed to investigate the impact of dietary interventions, specifically the reduction of saturated fat intake and an increase in polyunsaturated fat intake, on cardiovascular health.

The Oslo Diet-Heart Study involved 412 men who had already suffered a myocardial infarction 1-2 years before the start of the intervention.

Despite some known limitations, the Oslo Diet-Heart Study played a role in shaping early understanding on the relationship between dietary fat, cholesterol levels, and heart disease. Subsequent research and larger studies have contributed to a more nuanced understanding of the complex factors influencing cardiovascular health.

In this episode we discuss why this trial is important in the history of diet-heart research and how it connects to other seminal work in the field.

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About This Episode:

In 1959 a landmark clinical trial, often referred to as the LA Veterans Study, began with the aim to investigate the effects of replacing dietary saturated fats with polyunsaturated fats, on the progression of atherosclerosis and cardiovascular outcomes.

This was an eight-year clinical trial in 846 domiciled male veterans in the US. The diets between the control and experimental groups differed by saturated fat and polyunsaturated fat (particularly linoleic acid) content, but were similar in calories and total dietary fat.

The findings of the study suggested that replacing saturated fat with polyunsaturated fat was beneficial for reducing heart disease risk. However, the study also reported an unexpected increase in non-cardiac mortality in the intervention group, which raised concerns.

In this episode, we discuss why the LA Veterans Study was such a seminal trial and what we can learn from it.

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About This Episode:

The Lyon Diet Heart Study (LDHS) is often cited as one of the pivotal studies that helped establish the Mediterranean diet as a recognized and recommended dietary pattern for cardiovascular health.

A clinical trial conducted in Lyon, France, the LDHS showed significant reduction in cardiac death could be achieved in secondary prevention patients using a dietary intervention.

Conducted between 1992 to 1996, the study involved 605 participants who had previously experienced a heart attack (myocardial infarction).

LDHS showed an incredible 75% lower risk of cardiac death in these patients. This remarkable reduction was unexpected and led to considerable attention from the medical and scientific communities.

LDHS is interesting to dig into for several reasons. First, it’s clever methodology was able to account for some challenges of doing nutrition research. Second, the dietary intervention, whilst named as a “Mediterranean diet”, should perhaps be considered differently.

In this episode, Alan and Danny dig into all the details, highlighting some important lessons we can take from LDHS.

Links:

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• Past episodes referenced: Episodes 493, 481 & 317
• Further reading: How Diet Influences Heart Disease Risk

About This Episode:

The Sydney Diet-Heart Study was a clinical trial conducted in the 1960s and 1970s that aimed to examine the hypothesis that reducing saturated fat intake in the diet would lead to a reduced risk of heart disease.

However, it really only gained attention after a more recent re-analysis by Ramsden et al., which in recent years has been used as supporting evidence for the idea that increased polyunsaturated fat (PUFA), and specifically linoleic acid, in addition to reduced saturated fat intake, can increase heart disease risk.

This was based on the findings that substituting linoleic acid in place of saturated fat increased all-cause, CVD and CHD mortality.

This is of course counter to prevailing consensus and guidelines in this area, which routinely show reduced risk on replacing SFA with PUFA.

Could this trial undermine the common conclusions that replacing saturated fat with polyunsaturated fat decreases heart disease risk?

In this episode Alan and Danny discuss some of the crucial aspects to understand about this study and what it means for what conclusions can be made about the impact of PUFA broadly, and linoleic acid specifically, on our health.

Note: This is a Premium-exclusive episode, so in order to listen to the full episode you’ll need to subscribe to Sigma Nutrition Premium. 

About This Episode

Nutritional epidemiology has faced strong criticism over time. While some of the methodological limitations are fair, often there are criticisms that are misguided and inaccurate.

In this episode, Danny touches on a few examples of the misunderstandings of the field and how such claims can be addressed in a more accurate manner.

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Links:

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• Sigma's Recommended Resources

About This Episode:

The field of research exploring sex differences in exercise response has yielded intriguing findings, shedding light on the complex interplay between biology, physiology, and training adaptations.

One of the fundamental areas of investigation pertains to sex disparities in strength, power, and hypertrophy. Historically, it’s been well-established that males, on average, exhibit greater absolute strength and muscle mass compared to females. This discrepancy often traces its roots back to inherent physiological distinctions.

However, when it comes to responses to strength and hypertrophy training, the narrative becomes more nuanced. Research indicates that, when individuals of both sexes follow matched resistance training protocols, the relative improvements in strength and hypertrophy are quite similar.

So, do women need to be trained differently than men? The answer, it appears, is not as much as one might assume. The principles of progressive overload, specificity, and other training fundamentals remain constant. While individualization is key, the idea of drastically distinct training guidelines based on sex lacks compelling empirical support.

The guest in this episode, Dr. David Nolan, is a researcher in the area of sex differences in exercise response, and has looked at the influences of menstrual cycle and hormonal contraceptive use in female athletes on their performance.

In this episode, we discuss the research to date, and what this means practically for athletes and coaches.

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Previous episodes referenced:

• SNP17: Is Personalized Nutrition Superior to General Nutrition Advice?
• 414: Will Machine Learning Overtake Traditional Nutrition Research Methods?
• 469: Chrononutrition – New Findings & Updated Views

About This Episode: To mark the 500th episode of the podcast, Danny and Alan take a look at some of the current outstanding questions in nutrition science, what areas have largely been resolved, and how their own thinking has evolved and changed over time. This brings them into areas such as personalized nutrition, ultra-processed foods, time-restricted eating, salt & health, and the difference between being “evidence-based” and “reference-based”. We Discuss:

• Outstanding questions in nutrition science
  • Personalized nutrition
  • Ultra-prosessed foods (UPFs)
  • Diet-Microbiome-Health
  • Omega-3 Fatty Acids
• Largely resolved questions
  • Sodium & CVD risk
  • TRE/TRF
  • Macronutrient breakdown & weight loss
• Evolution in our thinking
  • Epistemology at the forefront
  • “Reference-based” to evidence-based
  • Reading research: understanding “highest quality evidence”

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About This Episode:

Sensory cues, comprising taste, smell, texture, and appearance, serve as the initial drivers that influence our food preferences and liking for particular items. These sensory cues can be both inherent, such as the natural sweetness of fruit, and learned, as in the association between a particular aroma and a favorite dish.

One crucial aspect of this research is delving into how sensory properties of food, like texture and taste, contribute to our choices and consumption patterns. Food texture, for example, plays a key role in determining how quickly we consume a meal, with softer textures often being associated with faster eating rates.

Sensory intensity and palatability are also central themes in this research. Moreover, research into dietary fat reveals intriguing phenomena like “fat blindness,” where the ability to discriminate different levels of fat diminishes as taste intensity increases. Understanding these relationships can help shed light on factors contributing to overeating and potential avenues for behavior modification.

To give us a better insight into this field of research, Professor in Sensory Science and Eating Behavior at Wageningen University, Prof. Ciarán Forde, is on the podcast to discuss these ideas.