There’s been a lot of scientific (and public) interest in the potential health benefits of dark chocolate.

Dark chocolate contains large amounts of cocoa, 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, flavanols have many health benefits.

Some fruits, vegetables, red wine and tea contain significant amounts of these substances. 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 meet many of the criteria that athletes are looking for to improve performance.

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

Putting dark chocolate to the exercise supplement test, nine moderately trained male participants volunteered to undertake a series of baseline tests looking at their maximal oxygen uptake (VO2 max ), lung gas exchange measures and two minute exercise bike time trial performance.

They performed each trial two weeks apart under conditions of either consuming 40 grams of dark chocolate or white chocolate (which contains no polyphenols) each day leading up to the trial.

Dark chocolate consumption improved time trial performance relative to both the baseline conditions and also white chocolate consumption.

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 covered compared to eating white chocolate.

There was also a significant six percent improvement in VO2 max under the dark chocolate conditions compared to baseline conditions. The same six 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.

Implications

This was only a small study however it prompts further research in the area. There also seems to be little harm in athletes trialling it for themselves.

Last Reviewed: 29/07/2019

© Norman Swan Medical Communications.



References

Patel RK et al. Dark chocolate supplementation reduces the oxygen cost of moderate intensity cycling. Journal of the International Society of Sports Nutrition 2015;:12:47.