When you think of foods that improve athletic performance, chocolate probably isn’t the first option that comes to mind.
We’ve known for a while that certain compounds found in chocolate, known as flavanols, are associated with health benefits to the heart and the brain. Epicatechin, in particular, has exhibited widespread effects throughout the body.
But some emerging evidence suggests that chocolate may also aid in exercise performance – weird as it may sound.
Here’s what the research says so far, and why it seems to work.
Effects of Cocoa on Aerobic Metabolism
A few years ago, researchers became interested in how compounds in chocolate might influence aerobic performance.
To test this, they randomized mice into four different conditions:
- Water + exercise
- Epicatechin-infused water
- Epicatechin-infused water + exercise
Groups 2 and 4 were put on a fifteen-day exercise program via treadmill. The other mice chilled and presumably did typical mouse things for the ensuing period.
The researchers performed biopsies of their hind legs. They found that the mice that were given epicatechin developed more capillaries in the leg muscles, which would enable their muscles to get more blood flow.
Additionally, the muscle cells appeared to be generating more mitochondria. More mitochondria result in greater energy production and better resistance to fatigue by skeletal muscle. Both of these factors would be expected to improve aerobic metabolism in the muscles. So the researchers put this to the test, by forcing all of the rodents to run on a treadmill to exhaustion.
Sure enough, the control mice drinking plain water became fatigued more rapidly than their counterparts that were assigned epicatechins. In fact, the mice that had been drinking water and training on the treadmill did about the same on the treadmill test as the mice that were given the cocoa polyphenols but didn’t work out!
Overall, though, the fittest rodents were in the group that both exercised and consumed epicatechins. This group ran approximately 50% further than the animals that did not consume the flavanols.
Effects of Cocoa on Circulation
Improvement in mitochondria and capillarization isn’t the whole story, though. Epicatechins from chocolate are also known to increase the bioavailability of nitric oxide. This effect is also a hallmark of nitrate-rich beetroot juice, which is a popular ergogenic.
Given that most people would find chocolate to be a hell of a lot more palatable than beetroot, researchers became curious about whether supplementing with chocolate could convey similar performance benefits.
They took nine amateur cyclists and divided them into two different groups. One group added 40 grams of dark chocolate to their diet; the other added 40 grams of white chocolate (devoid of epicatechin) in their diet as a control. After two weeks of this regimen, the cyclists performed a series of exercise tests. Then the cyclists switched chocolate types and repeated the experiment. This way, every participant was tested with both treatments.
The researchers found that when the cyclists consumed dark chocolate, they consumed significantly less oxygen when they were riding – and were able to ride one-tenth of a mile further – compared to when they were eating the white chocolate. The performance effects were not quite as pronounced as with the mice in the earlier study, but still impressive for such a small lifestyle change.
The researchers attributed the finding to increases in nitric oxide and nitrate levels. Nitric oxide dilates blood vessels and improves blood flow to skeletal muscles. This reduces the rate of oxygen use and should allow athletes to train longer and more intensely without fatiguing. This is indeed what the investigators found when they put the cyclists to the test.
First of all, it appears that the type of chocolate that you choose makes a big difference. The relevant polyphenols like epicatechin are most concentrated in dark chocolate – the darker, the better.
Epicatechins are most rich in cocoa powder and unsweetened baking chips. Dark chocolate (70%+) has about half as much, but is a lot less bitter and might be a little easier for people to eat. White chocolate contains little to none, which is likely why it has not been associated with performance improvements.
Also, it’s important to address how much chocolate you really need. The appropriate dose, in the context of exercise performance, is modest. In the mouse study, the rodents were given 1 milligram of epicatechin per kilogram of body mass. This translates to roughly five grams of dark chocolate when scaled up to humans. The cyclists in the other study ate 40 grams of Dove dark chocolate (about five pieces).
Finally, the research does suggest that plant compounds like epicatechin can provoke beneficial physiological responses in sedentary individuals. In fact, epicatechin is being investigated as a potential exercise mimetic (i.e., it mimics the effects of exercise). But the stimulus of exercise appears to dramatically increase the health and performance benefits. Alas, just eating chocolate and sitting on the couch is still not the optimal strategy for fitness.
Overall, it appears that modest amounts of dark chocolate moderately improve exercise performance. The ideal dose, and the extent to which the animal research applies to humans, is not entirely clear. But given that it’s delicious, it seems like one of those rare occurrences where something that seems bad is actually good for you.
Here is how I get my dose each morning: 2 scoops in my morning coffee!
Nogueira L, Ramirez-Sanchez I, Perkins GA, Murphy A, Taub PR, Ceballos G, Villarreal FJ, Hogan MC, Malek MH. Epicatechin enhances fatigue resistance and oxidative capacity in mouse muscle. 2011. J Physiol 589(Pt 18):4615-31.
Miller KB, Hurst WJ, Flannigan N, Ou B, Lee CY, Smith N, Stuart DA. Survey of commercially available chocolate- and cocoa-containing products in the United States. 2. Comparison of flavan-3-ol content with nonfat cocoa solids, total polyphenols, and percent cacao. 2009. J Agric Food Chem 57(19):9169-80.
Rishikesh Kankesh Patel, James Brouner, Owen Spendiff. Dark chocolate supplementation reduces the oxygen cost of moderate-intensity cycling. 2015. Journal of the International Society of Sports Nutrition 12:47.