A popular health supplement often promoted as an anti-ageing substance helps yeasts and worms live longer, but there is no evidence it does the same for humans, an Otago University study has found.
Resveratrol, believed by some to be the miracle substance in red wine that explains why French people who consume a high-fat diet suffer comparatively low rates of heart disease, is taken in supplement form by as many as 40,000 New Zealanders, an industry figure estimated.
Its benefits are said to include improved cardiovascular health, decreased likelihood of cancer, improved joint mobility, digestive health and brain function.
While there is no reason to suspect those benefits - many of which are backed by scientific studies on animals - don't occur, there is no evidence to suggest resveratrol promotes a longer life, said Dr Shinichi Nakagawa, from Otago University.
"It's marketed as an elixir of life, that extends life, and there is very little evidence for that."
Dr Nakagawa conducted a meta-analysis of 19 published papers on resveratrol which assessed its effect on survival. His research found evidence that resveratrol extended the life of yeasts and worms but was not proven to be effective in higher order lifeforms such as animals and humans.
"As such, we question the practice of the substance being marketed as a life-extending health supplement for humans," Dr Nakagawa said.
A separate study by Harvard Medical Researchers earlier this month concluded resveratrol does contain anti-ageing properties.
Auckland-based supplement company Abeeco promotes resveratrol as capable of slowing the ageing process and decreasing "its impact on the way you look and feel". Abeeco business manager Raewyn Bone said the multiple health benefits meant the product probably did increase life expectancy.
About Health, the company that first introduced resveratrol into New Zealand in 2006 and markets it under the brand Res-V Plus, makes no claim about the product's ability to extend life.
"It's definitely on the rise as a supplement, but not really for longevity reasons," About Health director Daniel King said. "There are some people who think it may well help people live longer, but you couldn't make an honest claim that it [will]."
Mr King, who has a science degree from the University of Auckland, said the company had published an article in its newsletter to customers that confirmed the lack of evidence the product was life-extending. The article stated resveratrol might not make people live longer but it could make them healthier for longer.
Mr King didn't dispute the Otago study's findings. "You'd have to say that is true. Look, it made mice live longer but in order to prove it makes a person live longer you'd have to wait an entire lifespan."
The Otago study hasn't debunked the theory red wine may have health benefits, including longevity.
"It doesn't negate that it's probably good for you," Dr Nakagawa said. "I have a red wine every now and then. However, this is probably not the answer for what they call the French paradox. Resveratrol in red wine is not the substance, I suspect, that is extending French people's lives."