The red-wine chemical resveratrol has the potential to fight diabetes, cancer, heart disease and dementia, according to a flurry of studies in the past decade. And a more tantalizing theory for some medical researchers suggests that the chemical, found in grape skins and other plants, could extend lifespan. But a new study casts serious doubt on the original research that suggested that theory. Resveratrol is no fountain of youth, the authors argue.
Resveratrol activates sirtuins, a group of proteins that regulate cell metabolism. That fact has been a cornerstone of recent medical research into longevity because of a 2001 study that showed that sirtuins extend lifespan on a cellular level. But an international team of gerontology researchers, lead by the Institute of Healthy Aging and the genetics department of University College London, was unable to replicate the results of that study.
The belief that resveratrol kicks sirtuins into gear and extends lifespan, originally observed in worms in 2001, was the foundation of multiple longevity studies. Just two years after the initial research, another study theorized that sirtuins increased the endurance of lab mice and attributed that to resveratrol's contributions to cellular energy levels.
These results spurred multimillion dollar investments in resveratrol, in hopes of creating a pharmacological fountain of youth. In 2008, pharmaceutical giant GlaxoSmithKline paid $720 million to buy Sirtris, a biotechnology company that was developing drugs to stimulate sirtuins. Recently though, doubts have emerged on whether or not resveratrol can directly increase lifespan, as originally observed in lesser species. And it may be, as the current study suggests, that sirtuins have no impact on aging in the first place.
In the recent study, published in Nature, worms were genetically manipulated so that their sirtuin gene was overactive. As expected, these worms lived longer than the control worms. However, the team concluded that the longer lifespan was due to an unrelated mutation at a second location in the genome. When that second mutation was bred out, they found no evidence that sirtuins boosted lifespan.
"We found that sirtuins don't actually increase lifespan in the animals that we looked at, the nematode worms and fruit flies," said co-author David Gems, a geneticist at the university. "This suggests that even a drug that did activate sirtuins would not slow aging."
Leonard Guarente, the sirtuins researcher at the Massachusetts Institute of Technology who published the original 2001 study, disputed the new findings. He argued that while a mutation is responsible for some of the anti-aging seen in the worms, sirtuins also have an impact.
So far, no one is suggesting that the resveratrol doesn't still work with anticancer and anti-inflammatory properties. The potential reduction of chronic disease risks associated with red-wine consumption may still help humans live longer through the prevention of ailments. Gems said that he believed his research will allow scientists to focus on sirtuins' (and resveratrol's) real health benefits, rather than on suspect anti-aging properties.
"The new paper is not a witch hunt," said Johan Auwerx, co-author of the 2006 report on mouse endurance and currently a professor of energy metabolism at the Laboratory of Integrative and Systems Physiology in Lausanne, Switzerland. "Most likely, sirtuins are not extending lifespan but it is a health-span gene, which is a rather discrete difference. It protects us against various stresses inflicted by our unhealthy lifespan. Whether it is a lifespan gene does not really matter for humans, because what counts is that it improves health."
"From what I have read over the years, my impression is that moderate consumption of alcohol in various forms can have health benefits," said Gems. "The idea that wine has some bioactive things in it apart from alcohol that are beneficial to health is an interesting one—more work should be done on it. As for red wine in particular, I just don't know—I prefer whiskey myself."