Chocolate comes from the seeds of the cacao plant, which is native to Africa and South America. Cacao, like other plant-derived foods, is a source of antioxidants. Antioxidants are compounds that keep you body cells healthy and intact. Antioxidants found in chocolate are known as cocoa phenols. One of these cocoa phenols, epicatechin, was featured in a study in the "Journal of the American Medical Association," which concluded that this antioxidant component of dark chocolate dilated veins and arteries leading to lower blood pressure in the study participants.
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An article in "Nutrition Reviews" reported that cocoa phenols improved health in three major ways: by prohibiting oxidation of low-density lipoprotein cholesterol, by dilating blood vessels leading to lower blood pressure and by reducing inflammation in the body. Low-density lipoprotein, or LDL cholesterol, is known as bad cholesterol due to its tendency to produce plaque when it is oxidized. Plaque is the substance that clogs veins and arteries leading to heart disease. Cocoa phenols do not decrease LDL levels, but they do help keep veins open and flowing by indirectly reducing plaque buildup.
In the JAMA study, participants were given 6.3 grams of dark chocolate daily, which is equivalent to about half of one miniature candy bar. The study participants had lower blood pressure levels after eating the chocolate daily. The study found that the participants had a small but scientifically significant reduction in systolic and diastolic blood pressure after the chocolate trials. Participants also had increased levels of S-nitrosothiols, substances formed from nitric oxide, in their blood. Researchers concluded that epicatechin, the aforementioned cocoa phenol, may have stimulated increased production of nitric oxide, which then formed the S-nitrosothiols that dilated the veins and arteries, leading to a decrease in blood pressure. In this study, white chocolate did not demonstrate a significant blood pressure-lowering effect.
Chocolate in the Diet
The three derivatives of the cacao bean that are used to make the chocolate that you eat are chocolate liquor, cocoa butter and cocoa powder. These three components make up cacao, or dark chocolate. Milk is added to cacao to make milk chocolate, and sugar, vanilla and other flavorings are added to produce the final flavor of the chocolate. A 2003 study published in "Nature" concluded that milk inhibits the absorption of antioxidants from chocolate. To get the full blood pressure-lowering effect, dark chocolate is a better choice than milk chocolate or white chocolate. Another study in the "Annals of Nutrition and Metabolism" showed that there is still some absorption of cocoa phenols when cocoa powder is dissolved in milk, such as in milk chocolate or even chocolate milk.
Dark and Darker
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You may have noticed various percentages listed on dark chocolate bars, such as 75 percent cacao or 86 percent cacao. The more cacao the bar contains, the darker the chocolate is and the more antioxidant activity you may expect from consuming the bar. In general, the more cacao the chocolate bar contains, the less sugar, vanilla, emulsifiers and other flavorings are present, so darker chocolate tastes more bitter and less sweet
- Journal of the American Medical Association: Effects of Low Habitual Cocoa Intake on Blood Pressure and Bioactive Nitric OxideA Randomized Controlled Trial
- Nature: Plasma Antioxidants From Chocolate
- Ghirardelli Chocolate: Chocolate Q & A
- Nutrition Reviews: The Emerging Role of Flavonoid-Rich Cocoa and Chocolate in Cardiovascular Health and Disease
- Annals of Nutrition and Metabolism: Milk Does Not Affect the Bioavailability of Cocoa Powder Flavonoid in Healthy Human
Tara Bzdok is a registered dietitian licensed in Texas, where she practices clinical nutrition as a renal dietitian. Bzdok completed her dietetic studies at Sage Colleges in Albany, N.Y. She also holds a bachelor's degree in English literature from University of Montana.