Sir

There has been much debate in the media about the potential health benefits of moderate wine consumption, and the components of wine that may be responsible. Recently, Konrad Howitz and colleagues reported an increased lifespan for yeast treated with resveratrol through the activation of sirtuins (Nature 425, 191–196; 2003). Because resveratrol is a polyphenol found in wine, these findings have been linked in media reports to studies suggesting that regular wine drinking can increase longevity (for example, see http://www.nature.com/nsu/030825/030825-1.html; and S. S. Hall, Science 301, 1165; 2003).

However, the claims being made for resveratrol are unjustified. There is no evidence that it would provide these benefits as part of a normal diet — even for wine drinkers.

It is not a simple matter to extrapolate the results of yeast studies to human health, especially when the studies on yeast used much higher concentrations of resveratrol than are available from wine drinking. Levels of resveratrol in wine are generally less than 5 mg per l, and it is heavily metabolized during the absorption process, resulting in extremely low plasma concentrations (D. M. Goldberg et al. Clin. Biochem. 36, 79–87; 2003).

In addition, the link between regular wine consumption and longevity is still not proven. Deaths from coronary heart disease and from all other causes are lower in people drinking two to three glasses of wine a day. This has been interpreted as evidence that regular wine drinking could increase longevity, but it has not yet been confirmed by population studies showing, for example, a large increase in the number of people who live beyond 80 years.

Wine drinking in the pursuit of a longer life should not be encouraged until we have a better understanding of the link between diet and health.