Heart-Healthy Chocolate? How Sweet It Is!

By Robin Hindery

The holidays are here, with all their culinary delights — and sometimes morning-after remorse. But before you feel too guilty about devouring that chocolate Santa, here’s an early Christmas present from UCSF Professor Mary Engler, PhD, RN: Chocolate may improve heart health. The key, says Engler, is chocolate’s rich supply of flavonoids, a group of plant-derived micronutrients that are believed to act as antioxidants, lower blood pressure, reduce inflammation and improve vascular health, among other benefits. While all types of chocolate contain flavonoids, dark chocolate is by far the best choice for those seeking to make both their heart and their sweet tooth happy, Engler said. “As amazing as it sounds, we’re finding that in regular, small amounts, dark chocolate has numerous heart-healthy benefits,” she said during a Nov. 20 talk sponsored by the UCSF National Center of Excellence in Women’s Health and the Center for Gender Equity. Engler, who directs the Cardiovascular and Genomics Advanced Practice program in UCSF’s Department of Physiological Nursing, has long been interested in nutritional interventions to prevent heart disease, but her research was previously confined to health food staples such as fruits and vegetables, which are known to be high in antioxidants. By the late 1990s, however, advances in technology and analytical methods allowed scientists to study more complex flavonoids, including those found in chocolate. Engler said she was “astounded” to see that when compared with other flavonoid-rich foods such as blueberries, tomatoes and tea, chocolate was the clear winner. Dark chocolate has 13 times the antioxidant capacity of broccoli, for example. Further study has only strengthened Engler’s faith in chocolate’s health-boosting abilities. In 2004, she published the results of a clinical trial of 21 healthy adults, each of whom consumed 1.6 ounces of either low-flavonoid or high-flavonoid dark chocolate every day for two weeks. Those who received the high-flavonoid chocolate experienced a significant improvement in blood vessel dilation, or expansion, without any weight gain or increase in blood cholesterol. Later, in a 2006 article for Nutrition Reviews, Engler compared dozens of studies documenting chocolate’s ability not only to improve blood vessel dilation, but also to lower blood pressure, reduce inflammation and prevent the formation of blood clots, which can lead to strokes and heart attacks. In addition, studies have shown, chocolate appears to produce an antioxidant effect, limiting the accumulation of harmful LDL cholesterol in the blood vessels. But before you start sprinkling M&M’s on your salad, Engler cautions, remember that a little bit of chocolate can go a long way. She recommends about 6.7 grams of dark chocolate per day for healthy adults. That’s less than one-tenth of a standard, 100-gram chocolate bar. Engler said she plans to continue her study of chocolate’s hidden wonders. She is currently seeking funding for a large, long-term clinical trial testing either dark chocolate with varying amounts of flavonoids or a purified chocolate flavonoid supplement. While her findings have obviously delighted others, Engler herself seems equally enthusiastic about what she describes as “a tasty treat with healthy benefits.” She ended her Nov. 20 talk with a quote from Marcia and Frederic Morton, authors of Chocolate: An Illustrated History: “Life without chocolate is life lacking something important.”