New Research Throws Doubt on Resveratrol

| May 28, 2013 | 1 Comment

A meta-analysis of multiple studies across animal species has found no evidence that resveratrol, the ingredient trumpeted as a health benefit in red wine, actually leads to higher-order species’ such as humans living longer.

The benefits of resveratrol have been hotly debated in scientific journals in recent years, with many promoting resveratrol as a magic bullet to help extend life expectancy. A multimillion dollar international supplement industry has now grown selling resveratrol pills. The marketing of these supplements often describes as evidence the ‘French Paradox’ – the belief that the health risks of rich diets such as those in French culture can be mitigated by moderate consumption of red wine.

But research published in Biology Letters journal and international press by University of Otago researchers, who were funded by Gravida, NZ’s Centre for Growth and Development, says this may be true for lower life forms – but not complex beings or humans.

The researchers systematically compared 19 separate resveratrol studies across 6 species and mined their data, methodology and results. They found that while resveratrol contributed to life extension in lower-level species such as yeast and nematodes (breed of worms), there was no consistent evidence of the same effect in higher-order species including fruit flies or mice, the closest species to humans that has been covered in published research to date.

In comparison, another meta-analysis by the same group looking at the effects of dietary restriction of either calories or proteins on life expectancy showed more consistent results across species (published in Aging Cell journal, 2012)

“At a glance, our results confirm the claims that resveratrol extends longevity. However, the analytical method we have used allows us to observe where this statement is unable to be supported. Both the species model and our ‘best’-fit meta-analytic model show a stark contrast between our hermaphrodite/asexual reference group (yeast and nematodes) and the higher-order animals,” co-authors Katie Hector, Malgorzata Lagisz and Shinichi Nakagawa say in Biology Letters.

“At a time when human trials testing for health benefits from resveratrol are in their early days, we believe it is inappropriate for resveratrol to be marketed as a life-extending health supplement when our analysis of the current knowledge provides such varied results,” they conclude.

Meanwhile supporters are now shifting their focus to look at whether resveratrol offers other health benefits such as protection against metabolic diseases such as obesity and diabetes as well as high cholesterol and clotting. In March this year for example, Professor David Sinclair, Harvard Medical School who is also co-founder of Sirtris, a GlaxoSmithKline supplements company, published research that described how resveratrol increases the activity of a specific sirtuin,SIRT1, that protects the body from diseases by revving up the mitochondria.

Dr Nakagawa is clear that his group’s meta-analysis did not look at other health claims and was focused on anti-aging evidence. “There could be something in these other effects, but we haven’t looked at that in this study,” he says. “Especially with clinical trials coming, it would be good to look at this evidence and we might well do that next.”

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