Charcoal is credited with getting rid of gas, bloating, hangovers and generally helping us cleanse and detox. Healthy or Hoax finds out if the claims are backed up by science.

By Liz Garton

Experts say we're witnessing a hijacking with the current trend of putting activated charcoal in our foods, drinks and beauty and dental products.

Activated charcoal is made by heating unactivated charcoal to a very high temperature in the presence of an inert gas.

Professor Ian Shaw, Director of Biochemistry and Professor of Toxicology at the University of Canterbury, said this process creates lots of pores in the charcoal, which makes it have a very, very high surface area.

"The chemistry of the charcoal enables it to bind to many, many different sorts of molecules and with this huge surface area, it can bind a very large amount of chemical material. So if you put some charcoal into a liquid, for example, that might have some chemicals in it, then the chemicals will bind to the charcoal and remove them from that liquid."

Which is one reason activated charcoal has long been used as a detoxifier.

"It looks like the Phoenicians in around about 400 BC actually made activated charcoal by heating charcoal in a fire to very high temperatures. And they use that powdered activated charcoal to purify their water," said Professor Shaw.

And for many years toxicologists have used charcoal as a treatment for poisoning.

"So, the whole trend around this whole activated charcoal movement is basically it stems from the fact that in medical settings, activated charcoal has been used to treat overdose of drugs and poisoning and things like that," he said.

But Dr Rajshri Roy says the idea of charcoal as a detoxifier has been hijacked by the food and beauty industry.

"So our body has organs that take care of the detoxing process. No particular food helps with detoxing. Your kidneys are going to do that, your lungs are going to do that, and your liver is going to do that," she said.

And Professor Shaw goes even further.

"I'm really unhappy about just adding something that indiscriminately binds to so many things on the grounds that it will stop you getting exposed to toxic chemicals in your food," he said…

Go to this episode on rnz.co.nz for more details