Thursday, May 3, 2012

New study reveals how resveratrol might work (don’t lose your SIRT)

The latest study on resveratrol, the touted polyphenol from red wine, seems at first glance to restore some lost credibility to its increasingly questioned anti-aging capabilities. It has been widely reported but we know from experience by now that a single study never tells the whole story. The whole story would take more space than I have here so here is what you need to know:

There is a unique phenomenon called caloric restriction that extends lifespan dramatically, at least in experimental animals and organisms. By limiting caloric intake severely, a metabolic change occurs that results from activation of a family of genes know as SIRT, which code for proteins known as sirtuins. Resveratrol has been reported to activate sirtuins and thereby cause lifespan extension, at least for yeast cells, fruitflies and worms. Getting it to do the same thing in mammals such as mice and men has been problematic however, casting doubt on the use of resveratrol as a miracle anti-aging tonic. Some labs have reported that resveratrol does not in fact activate SIRT. Meanwhile, the company founded to develop resveratrol-based pharmaceuticals (Sirtris) has scrambled to maintain their case.

This latest study, from Dr. David Sinclair (cofounder of Sirtris) employed a strategy using mice with the SIRT gene “knocked out.” So by testing resveratrol’s effects in knockout vs normal mice, the role of sirtuins can be determined. What they found was that metabolic measurements were healthier in the normal mice given a high-fat diet plus resveratrol, but not the SIRT knockout mice. So resveratrol’s effects do depend on SIRT, (as well as an unhealthy diet) implying that it is a sirtuin activator after all. We are still left, however, with the question of how much this relates to human health.

Recall from previous posts here that there isn’t enough resveratrol in wine to explain the well-established health benefits including longer lifespan associated with moderate consumption. There is also the problem that resveratrol is quickly transformed after ingestion into a different molecule called piceatannol.  So before concluding that this recent study confirms that resveratrol works as a supplement, have a glass of wine and mull it over.