Daily supplements of resveratrol may improve how the human body responds to insulin, the hormone responsible for sugar and fat metabolism, Hungarian researchers report for the first time.
According to findings published in the British Journal of Nutrition, a daily 10 milligram dose of resveratrol was associated with reductions in insulin resistance in type-2 diabetics.
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.
“Whether resveratrol (or some of its future derivatives) becomes a useful tool in combating type 2 diabetes is difficult to tell, although the fact that recent studies (including the present study) have demonstrated that the efficacy of resveratrol at low doses might increase the possibility for its medicinal application,” report researchers from the University of Pécs.
“On the other hand, the present study definitely suggests that resveratrol could become a useful tool in gaining a deeper understanding of the mechanisms underlying the development of insulin resistance and oxidative stress.”
Resveratrol’s rosy potential
Resveratrol, a powerful polyphenol and anti-fungal chemical, is often touted as the bioactive compound in grapes and red wine, and has particularly been associated with the so-called 'French Paradox'. The phrase, coined in 1992 by Dr Serge Renaud from Bordeaux University, describes the low incidence of heart disease and obesity among the French, despite their relatively high-fat diet and levels of wine consumption.
Interest in the compound exploded in 2003 when research from David Sinclair and his team from Harvard reported that resveratrol was able to increase the lifespan of yeast cells. The research, published in Nature, was greeted with international media fanfare and ignited flames of hope for an anti-ageing pill.
According to Sinclair’s findings, resveratrol could activate a gene called sirtuin1 (Sirt1 – the yeast equivalent was Sir2), which is also activated during calorie restriction in various species, including monkeys.
Since then studies in nematode worms, fruit flies, fish, and mice have linked resveratrol to longer lives. Other studies with only resveratrol have reported anti-cancer effects, anti-inflammatory effects, cardiovascular benefits, anti-diabetes potential, energy endurance enhancement, and protection against Alzheimer’s.
The Hungarian researchers recruited 19 people type-2 diabetics and randomly assigned them to receive either resveratrol supplements (two 5 milligram doses from Argina Nutraceuticals, Hungary) or placebo for four weeks.
Results showed that after four weeks of resveratrol supplementation, the participants showed a significant decrease in insulin resistance, compared to the placebo group.
In terms of a potential mode of action for the polyphenol, the researchers noted that this may be related to its antioxidant activity, because oxidative stress is “widely accepted” as a key driver in the onset of insulin resistance.
There is also the possibility that resveratrol’s potential benefits are linked to its ability to activate Akt phosphorylation - an intracellular insulin dependent protein that facilitates the uptake of glucose into cells. Indeed, an increase in the levels of phosphorylated Akt (activated) to Akt was observed.
“The present study shows for the first time that resveratrol improves insulin sensitivity in humans, which might be due to a resveratrol-induced decrease in oxidative stress that leads to a more efficient insulin signalling via the Akt pathway,” concluded the researchers.
Source: British Journal of Nutrition