From Ergo Log
Taking a supplement that contains piceatannol, a metabolite of resveratrol, may reduce fat mass and increase lean body mass. We base this speculation on Asian in-vitro studies, which have shown that piceatannol inhibits the uptake of glucose by fat cells but stimulates its uptake by muscle cells.
You'd expect muscle cells to grow better if they can absorb more nutrients from the blood. Researchers at Tokyo University of Agriculture and Technology in Japan announced last year that piceatannol may well have this effect on muscle cells. [Biochem Biophys Res Commun. 2012 Jun 8;422(3):469-75.]
The Japanese researchers exposed muscle cells to glucose and piceatannol in test tubes and observed that the piceatannol boosted the muscle cells' uptake of glucose. Piceatannol activates the energy sensor AMPK and GLUT4, a glucose transporter that is activated by intensive exercise and helps muscle cells to absorb glucose without the need for insulin.
Studies at cell level are interesting, but animal studies are more interesting. So the Japanese gave obese, insulin-resistant mice 50 mg piceatannol per kg bodyweight every day. The human equivalent of this dose would be in the region of 200-350 mg per day. The glucose level of the mice that had received the piceatannol went down more quickly than that of the mice that had not been given piceatannol. The mice that had been given piceatannol also gained a little weight.
The Japanese researchers didn't look at the effect of supplementation on body composition, but the results of a Korean-American in-vitro study done in 2012 indicate that there may well be an effect. [J Biol Chem. 2012 Mar 30;287(14):11566-78.]
In that study the researchers exposed fat cells to mixtures of piceatannol and insulin and observed that the higher the piceatannol concentration, the less fat the cells stored. The second figure below shows how that happens: as the piceatannol level rises in a fat cell, the insulin receptor's functioning declines.
The researchers were able to show that the piceatannol molecule attaches itself to the insulin receptor and then somehow hinders the signals that it transmits to the cell. The figure above shows how the researchers think this happens.
"Our finding of a direct binding between piceatannol and the insulin receptor and the inhibitory role of piceatannol in insulin receptor tyrosine kinase activity and its subsequent phosphorylation cascade of insulin-signaling pathway reveals a new mechanism by which a natural polyphenolic stilbene modulates adipogenesis", the researchers conclude.
Less glucose uptake in fat cells, more uptake of glucose in muscle cells, via GLUT4. Piceatannol is an interesting candidate for testing in sports drinks or post-workout supplements.
The idea that plant metabolites can reduce the absorption of nutrients from the blood by fat cells and increase it in muscle cells is not new. Biotest's bodybuilding supplement Indigo-3G is based on this principle and contains anthocyanin cyanidin-3-glucoside as active ingredient. Animal studies have been shown that anthocyanins can improve body composition.
Biochem Biophys Res Commun. 2012 Jun 8;422(3):469-75.