Tigst Assefa Breaks Women’s-Only Marathon WR RW+ Membership Benefits. Best Running Headphones new research from Kingston University in England, epicatechin, a nutrient found in cocoa beans, may also have measurable performance benefits for athletes, similar to those of beetroot juice (a popular choice for a performance boost). 

The researchers selected nine leisurely, yet dedicated, healthy cyclists and measured the effects of daily chocolate consumption on two stationary bicycle tests. They monitored the athletes’ overall fitness level and oxygen uptakes during 20 minutes of steady cycling, and during a two-minute full-speed sprint.

Over the next two weeks they were divided into two groups. Both groups incorporated 40 grams of chocolate into their daily diets, but the first group ate dark chocolate while the second was given white chocolate, which has little to no epicatechin nutrients due to processing. 

After two weeks the cycle tests were repeated. Then participants swapped groups—those who ate dark chocolate were now given white, and vice versa, and the tests were given again two weeks later.

The results were clear. The group that consumed dark chocolate during the sprints displayed slight, but undeniable improvements in distance. The cyclists traveled one tenth of a mile longer than their initial tests.

More significantly, dark chocolate caused participants to require less oxygen intake than both the white chocolate and baseline 20-minute tests. Dark chocolate consumption revealed a 21 percent improvement when compared to the tests without it and 11 percent to white chocolate tests.

It’s that decreased oxygen demand that interests Jane Burrell Uzcategui, M.S., R.D., and nutrition instructor at Syracuse University. 

“What this research shows us is that [dark chocolate] might be useful for those that are running 5Ks. That moderate intensity, short duration exercise,” she said. “Think of a relatively competitive, runner going to run a 5K in 20 minutes.” 

Dark chocolate may enhance such a runner’s endurance, like beetroot juice, but Uzcategui thinks results will dwindle with prolonged race time. For example, epicatechin likely won’t help individuals taking 45 minutes to complete a 5K, she said.

“My reservation [to dark chocolate] would be that if people just start adding it to their diet without really thinking about,” said Uzcategui.

She advises those thinking of eating more dark chocolate (that's at least 70 percent cacao) to be mindful, remaining aware of portions (it's still high in calories), how often they eat it, and what results they hope to achieve with it. Scientists don’t yet know how much chocolate is the sweet spot.