The controversy on resveratrol, the antioxidant compound of wine

Some doctors think that, although popular, benefits aren’t proven but a recent research shows that resveratrol activates sirtuins, so in future could be used against diabetes

by Aliona Avduhova

Resveratrol (trans-resveratrol) is a phytoalexin produced naturally by several plants, most famous is grapewine, when under attack by pathogens such as bacteria or fungi.

This compound is an antioxidant dietary supplement that is widely promoted to help prevent several age-related and malignant diseases.
This reputation is obtained in particular by the French paradox, the observation that the French suffer a relatively low incidence of coronary heart disease, despite having a diet relatively rich in saturated fats.
All attention concentrate on resveratrol but the quantity in wine seems too low to account for the French paradox.
Professor Roger Corder and team have identified a particular group of polyphenols, known as oligomeric procyanidins, which they believe offer the greatest degree of protection to human blood-vessel cells. Tests with 165 wines showed that these are found in greatest concentration in European red wines from certain areas, which correlates with longevity in those regions.

Some doctors begin to doubt about health benefits of resveratrol, most of all, for the the difficulty in translating these effects to humans is the problem of absorption.
The studies on this compound was, indeed, in vitro or on mices or other animals.

In 2006, Italian scientists obtained the first positive result of resveratrol supplementation in a vertebrate. Using a short-lived fish, Nothobranchius furzeri, with a median life span of nine weeks, they found that a maximal dose of resveratrol increased the median lifespan by 56%.

Also interesting the results about relations between cancer and resveratrol.
Resveratrol treatment appeared to prevent the development of mammary tumors in animal models; however, it had no effect on the growth of existing tumors. Paradoxically, treatment of pre-pubertal mice with high doses of resveratrol enhanced formation of tumors. Injected in high doses into mice, resveratrol slowed the growth of neuroblastomas.

About humans, once consumed, it should be rapidly metabolized by the intestines and liver, the first organs to process it.
The theory that resveratrol from wine could have higher absorption than from a pill has been disproven by two studies.

A recent study by the Southwestern Medical Center of University of Texas, that will be published on scientific magazine Endocrinology in the December 2009. illustrates that resveratrol activates sirtuins, a class of proteins that are thought to underlie many of the beneficial effects of calorie restriction. Previous studies in mice have provided compelling evidence that when sirtuins are activated by resveratrol, diabetes is improved. Sirtuin activators are now being tested in humans as anti-diabetic compounds.
Sirtuins are expressed virtually everywhere throughout the body and until now, little has been known about what tissues mediate resveratrol's beneficial effects. Knowing where in the body the beneficial effects of activated sirtuins are mediated could help in the development of more effective targeted diabetes medications.
"These findings may lead to new strategies in the fight against type 2 diabetes – said Roberto Coppari, co.author of the study - by knowing that the brain mediates resveratrol's anti-diabetic actions, industry can now focus on developing sirtuin activators that directly target the brain. When orally-delivered, these drugs will likely improve diabetes without affecting the other organs in which activation of sirtuins may not always be beneficial."

Long term effects of using resveratrol are as of yet unknown