Dark chocolate: the next hot sports supplement?

In the search for performance improvements in exercise, researchers are now casting their eye over the growing benefits of dark chocolate. The known health benefits of this tasty treat may even translate into improved athletic performance as well.

There has been much scientific (and public) interest in the potential health benefits of dark chocolate. Dark chocolate contains large amounts of cocoa, which is the seed portion of the cocoa tree. Cocoa is rich in a group of compounds called flavanols. Originally discovered because of their potent antioxidant activity, these flavanols have been found to have many health benefits. While cocoa is rich in flavanols, fruits, vegetables, red wine and tea all contain significant amounts of these latest natural wonder substances.

What’s special about dark chocolate?

Far from being just an antioxidant, flavanols can improve blood flow, reduce oxygen cost, improve insulin sensitivity and improve immune responsiveness. It helps achieve this through increased bioavailability and bioactivity of nitric oxide. The potential benefits from flavanols on nitric oxide production tick many of the boxes that athletes are looking for in improving performance.

Most of the research on dark chocolate has looked at the cardiovascular health in people with pre-existing medical conditions. There has only been a limited focus put on exercise performance in a more healthy sporty population.

On your bike

Putting dark chocolate to the exercise supplement test, 9 moderately-trained male participants volunteered to undertake a series of baseline tests looking at their maximal oxygen uptake (VO_2max), lung gas exchange measures, and 2-minute exercise bike time trial performance. They performed each trial two weeks apart under conditions of either consuming daily 40 grams of dark or white chocolate (which contains no polyphenols) leading up to the trial.

Dark chocolate consumption improved time trial performance relative to both the baseline conditions and also white chocolate consumption conditions. This equated to a 17 percent greater distance covered when eating dark chocolate compared to the start of the experiment. And 13 percent more distance was covered compared to eating white chocolate.

There was also a significant 6 percent improvement in VO_2max under the dark chocolate conditions compared to baseline conditions. The same 6 percent improvement was also seen when dark chocolate was eaten compared to white chocolate, but this didn’t reach the level of statistical significance. There were no statistical differences in blood lactate, heart rate, or blood pressure between the different experimental conditions, but dark chocolate showed a trend for improving many of these measures.

Keep in mind with this study that the taste of dark chocolate is quite distinct so it was not possible to blind the participants to what they were eating. So some placebo effect could have played a role if participants expected the chocolate to have a benefit.

What it all means

This was only a very small study. But as far as proof of concept goes, it certainly gives a green light to more research in this area. When you put in context that all that is being used is a small amount of dark chocolate, then there appears little harm in athletes jumping the gun early and trialling it for themselves.