Many supplements work well on rodents, but are disappointing when given to humans. Resveratrol is not one of these supplements. Scientists at the University of Maastricht in the Netherlands gave the stuff to 11 overweight men, and found that resveratrol had almost the same effects as it does in animal experiments – they were just more modest.
Studies on simple organisms show that resveratrol extends lifespan. Give it to mice and their endurance capacity increases because they burn fat more efficiently. Animal studies have also shown that resveratrol has a slimming effect, and makes obese mice healthier. [Cell Metab. 2008 Aug;8(2):157-68.]
Resveratrol's effect works through the enzyme AMPK. AMPK becomes active when cells have less energy available and the amount of AMP in the cells increases. [AMPK stands for AMP-activated Kinase]. AMPK enables cells to absorb more glucose from the blood, to burn more fatty acids and prevents nutrients from being converted into glucose. AMPK also indirectly activates repair processes. Many of the positive health effects of physical exercise stem from the effect of AMPK.
The Dutch researchers gave their test subjects 150 mg resveratrol daily for 30 days. They used resVida, made by DSM.
For obvious reasons DSM did not fund the research. Animal studies have already resulted in so much positive exposure in the media for resveratrol that a human study – and this is the first – has little to add.
Although the effects that the researchers observed were all subtle ones, they did all point in the same direction: resveratrol's effects strongly resemble those caused by physical exercise or weight loss. The figures below show that resveratrol activates AMPK [pAMPK], and via AMPK also activates SIRT1, an enzyme that initiates repair processes in cells.
In the men's muscle cells there was an increase in the activity of enzymes that are involved in fatty acid burning, such as citrate synthase.
Muscle and liver cells stored more fat, probably in the form of a 'working supply' because the cells had started to burn more fat.
Resveratrol reduced the blood concentrations of the inflammatory protein TNF-alpha, insulin and glucose.
Energy expenditure went down, as did fat oxidation. This occurred during rest periods, for example when the subjects were asleep. Resveratrol probably makes metabolism more efficient in the same way that endurance sports also make athletes' metabolism more efficient.
In the dose used in the experiment and without physical exercise, resveratrol doesn't work as a slimming supplement. But the study does make one wonder about the effect resveratrol would have if it were combined with training or substances such as EGCG, capsaicin or caffeine.
Cell Metab. 2011 Nov 2;14(5):612-22.