Monday, August 22, 2011

Resveratrol derivative helps obese lab mice live longer – so what?

Do the new findings about the resveratrol derivative SRT-1720 extending the normally shortened lifespan of obese mice tell us anything new? It’s been a long and ultimately disappointing road with the red wine derivative resveratrol, once touted as the basis for miracle anti-aging drugs and now a fading star. As I have described here before, resveratrol was purported to activate an enzyme system known as sirtuins, which in turn activate anti-aging genes that trigger a unique lifespan extension phenomenon normally associated with severe caloric restriction. Take a pill and skip the starvation diet was the promise, and live up to 40% longer. The idea was so compelling that the biotech company Sirtris was founded to exploit more potent (and patentable) resveratrol derivatives such as SRT-1720.


This latest report showed that giving mice resveratrol after rendering them morbidly obese through an unhealthy diet helped them live longer than they normally would have, by improving insulin sensitivity and otherwise normalizing metabolic parameters thrown out of whack by the diet. But there are problems with the study: firstly, the subject mice still didn’t live as long as mice on a healthy diet. Secondly, there isn’t really anything new here; this has all been reported before.

The real problem is that neither resveratrol nor any of its derivatives has been proven to directly activate sirtuins in the first place. In fact, several labs other than Sirtris have definitely concluded that it doesn’t, that the initial reports were an artifact of the testing method. SRT-1720 may prove to be a useful drug for type 2 diabetes, joining a crowded market. But – and here’s the interesting twist – another diabetes drug, metformin, does extend lifespan in mice on a normal diet.

I have always been a little bit uncomfortable with attributing wine’s well-established health benefits to resveratrol. There isn’t enough resveratrol in wine to explain all of the good things that a glass or two with dinner imparts. There are a lot of things in wine besides resveratrol, including alcohol, and a lot of healthy habits that moderate wine drinkers have. So while I wish the good people at Sirtris all the best of luck, let’s not forget the simple things we can do for a long and healthy life now.

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