via NYTimes Well...
"Adding a little dark chocolate to a training diet may effortlessly improve endurance performance, according to a new study of sports nutrition. The findings provide ammunition both for athletes looking for an edge and those hoping for an excuse to indulge.
For some time, dark chocolate has been touted as a relatively healthy treat, with studies showing that small amounts may have benefits for the heart and brain. Most of this research has focused on the role of a substance called epicatechin, a plant nutrient found in cocoa. Dark chocolate is generally rich in epicatechin, though levels vary, depending on how the sweet was produced.
Epicatechin is known to prompt cells that line blood vessels to release extra nitric oxide, a substance that has multiple effects in the body. Nitric oxide slightly increases vasodilation, or a widening of the veins and arteries, improving blood flow and cardiac function. It also gooses muscle cells to take in more blood sugar, providing them with more energy, and it enhances the passage of oxygen into cells.
The upshot of these findings would seem to be that “recreational athletes who would like to improve their performance” might consider swapping a daily cookie or soda for a square or two of dark chocolate, said Rishikesh Kankesh Patel, a graduate student at Kingston University who led the study."