Like certain other foods such as berries and green tea, cocoa powder is high in antioxidant chemicals known as polyphenols. In cocoa, the polyphenol family known as the flavanols predominates. Studies have shown that these polyphenols are good for the heart.
One of the first studies to examine how these polyphenols affect cholesterol levels was conducted by researchers from the University of Hull, England, and published in the journal Diabetic Medicine in 2010. The experiment was a crossover study, meaning that participants were randomly assigned to one of two conditions (experimental or control), and then the two groups were switched. In this manner, the researchers could compare the effects of the intervention on specific individuals as well as the group as a whole.
The randomized, double-blind study involved 12 participants with type 2 diabetes. The experimental intervention involved feeding them 45 g of high-polyphenol chocolate per day, while the control intervention involved an equal amount of low-polyphenol chocolate. The researchers found that consumption of high-polyphenol chocolate was associated with an increase in HDL ("good") cholesterol and a decrease in the total cholesterol to HDL ratio.
Chocolate also lowers LDL cholesterolThese findings were confirmed and expanded in two other studies conducted over the next two years. The first, published in the European Journal of Clinical Nutrition in 2011, was a meta-analysis of 10 prior clinical trials on cocoa consumption and cholesterol. The researchers found that in short-term interventions, increases in cocoa consumption significantly reduced levels of both LDL ("bad") and total cholesterol, without significant effects on HDL cholesterol.
A second study, conducted by San Diego State University researchers and presented at Experimental Biology 2012, compared 31 people who were assigned to eat either white chocolate (zero percent cocoa) or dark chocolate (70 percent cocoa). The researchers found that those who ate 50 g of dark chocolate per day for 15 days had significantly higher levels of HDL cholesterol and lower levels of LDL cholesterol. Notably, they also had significantly lower levels of blood sugar!
The news gets even better. According to a 2012 study led by Penn State researchers and published in the American Journal of Clinical Nutrition, chocolate doesn't just lower your levels of LDL cholesterol, but also slows the rate at which LDL oxidizes. This is important because the oxidation of LDL is believed to play a key role in the hardening of arteries. Slowing this oxidation may actually slow the development and progression of heart disease.
The crossover study was performed by assigning 23 participants to eat either a standard U.S. diet with the flavonoids deliberately stripped away, or the same diet with an added 1.25 oz of cocoa powder and dark chocolate per day. Both diets contained equivalent amounts of caffeine and theobromine (both found in chocolate). Cocoa butter was added to the control diet to compensate for the extra cocoa butter found in the chocolate added to the other diet.
The researchers found that LDL extracted from study participants oxidized significantly more slowly following the chocolate diet than following the control diet. In addition, total antioxidant capacity and HDL cholesterol were significantly higher after the chocolate diet.
Consumers should note that much commercial chocolate is low in polyphenols and high in sugar and saturated fat. A good way to get the health benefits of chocolate without the risks is to add dark unsweetened cocoa powder to your meal.