Dark chocolate is the healthiest food that also doubles as dessert. Who doesn’t enjoy an indulgent square of dark chocolate on occasion? Fortunately, you don’t have to feel guilty about eating a square or two as the health benefits of dark chocolate are proven.
Dark chocolate is often touted for its heart-healthy benefits due to its ability to lower blood pressure and improve blood vessel function. But, if you exercise, you might enjoy another benefit of nibbling on dark chocolate in moderation. A small study shows that munching on this satisfying treat may boost exercise endurance. This means that dark chocolate may improve performance in some sports, especially endurance events like long-distance running or cycling.
Chocolate and Exercise: What the Study Showed
Researchers at Kingston University enlisted nine amateur cyclists. First, they asked the cyclists to complete a fitness test to measure their baseline level of aerobic fitness. Then, they divided the subjects into two groups. One cycling group replaced one of their snacks each day with four squares of dark chocolate. The chocolate was tested and confirmed to be high in flavanols. The other group ate a similar quantity of white chocolate. White chocolate doesn’t contain flavanols at all. In total, the participants ate 40 grams of chocolate per day in place of another snack.
Then, the cyclists took part in cycling fitness tests where they recorded how much oxygen the participants used during their workouts. After a week, the cyclists switched the chocolate type they consumed. The dark chocolate eaters consumed white chocolate and vice versa and the tests were repeated. After tabulating the results, the researchers found the cyclists required less oxygen during a cycling workout when they ate dark chocolate as opposed to white chocolate. The cyclists were also able to cover more distance during time trials. So, in this trial, dark chocolate improved exercise endurance while white chocolate did not.
Dark Chocolate and Endurance
Why might dark chocolate improve exercise endurance? The key seems to stem from dark chocolate’s ability to boost nitric oxide, a gaseous chemical produced by the endothelium, a layer of tissue that lines blood vessels. When cells within the endothelium produce more nitric oxide, blood vessels dilate and can deliver more oxygen delivery to muscles and tissues. When muscles receive more oxygen, they fatigue less quickly, and you can exercise longer. Another food, beetroot juice, also boosts nitric oxide production and is linked with greater exercise endurance. So, beetroot juice and dark chocolate may both be beneficial for people who play certain types of sports or do endurance exercise.
This isn’t the first study to show dark chocolate improves exercise endurance. A study involving cyclists found that those who ate dark chocolate before cycling sessions used less oxygen when they cycled at a moderate intensity. They also cycled a longer distance during a timed, 2-minute trial.
Chocolate, Flavanols, and Epicatechin
How does dark chocolate boost nitric oxide production? We know that dark chocolate is rich in antioxidants called flavanols. One flavanol, epicatechin, seems to trigger the endothelium of the blood vessel to produce more nitric oxide. It’s the cocoa bean itself that contains epicatechin. To get the benefits, you have to consume dark chocolate with enough epicatechin. White chocolate is devoid of it and milk chocolate contains far less than dark chocolate. So, choose your chocolate wisely.
Even if you choose a dark chocolate bar, there’s no guarantee that it contains enough epicatechin to make a difference. You’ll need a dark chocolate bar that is at least 70% cacao, a measure of how much of the bar is made of some part of the cocoa bean. In most cases, the higher, the better. However, independent testing of chocolate bars shows that a higher cacao content isn’t always indicative of an epicatechin-rich bar. For example, independent testing of bars shows that some bars labeled as 80% cacao may have less than one marked as 60% cacao. So, cacao content is only a guideline. It pays to do your research if you’re looking for a bar that maximizes exercise endurance.
Also, avoid dark chocolate bars that were alkalinized or Dutch processed. Cocoa beans in their natural state are bitter and Dutch processing or exposing the beans to alkali helps cut the bitterness. Unfortunately, it also destroys many of the flavanols, including epicatechin, that gives dark chocolate its health benefits. So, steer clear of alkalinized chocolate and cocoa.
Other Reasons to Enjoy Dark Chocolate
Improved exercise endurance isn’t the only reason to enjoy dark chocolate. Preliminary studies show that ingredients in dark chocolate may improve cognitive function and the benefits may be short-term AND long-term. One study found that reaction time and memory were better two hours after a group of young adults consumed dark chocolate.
In another study, older adults who took a supplement made with high-flavanol cocoa for 3 months performed better on memory tests. Other studies suggest that ingredients in dark chocolate, likely flavanols, increase insulin sensitivity and reduce inflammation. This may partially explain why dark chocolate is such a heart-healthy snack.
The Bottom Line
Now, you have one more reason to add modest amounts of dark chocolate to your diet. That’s a tough prescription, isn’t it? If you’re an athlete, munching on some may improve your endurance and help you cover a little more ground before you have to stop due to fatigue. Choose wisely though. Avoid dark chocolate with a high sugar content or one that was Dutch processed. Don’t overdo it either. Chocolate is still a calorie-dense food, but it’s good to know that something that tastes so decadent is actually good for you.
Kingston University – London. “Eating dark chocolate every day could help boost athletic performance, Kingston University research reveals”
Eur J Nutr. 2011 Oct;50(7):595-9. doi: 10.1007/s00394-011-0172-9. Epub 2011 Feb 16.
Appetite. Volume 100, 1 May 2016, Pages 126-132.
Harvard Health Publishing. “Your Brain on Chocolate”
Scientific American. “Why Is Dark Chocolate Good for You? Thank Your Microbes”