Chocolate might be one sweet treat that’s actually good for people with diabetes. In a study in the Journal of the American College of Cardiology, researchers found that cocoa can reverse some of the damage that diabetes has on blood vessels, possibly protecting against heart disease.

Type 2 diabetes is a disease of modern times, linked to diets high in fat and simple carbohydrates like those found in white flour and sugar. Its prevalence is increasing around the globe and with it come complications like heart, kidney, and eye disease—most of which are related to blood vessel damage.

The power of chocolate

Plant chemicals called flavanols are found in cocoa, as well as in fruits, vegetables, tea, and red wine. Studies have found that flavanols can help lower blood pressure, decrease blood stickiness (preventing clot formation), increase insulin sensitivity, and lower LDL (“bad”) cholesterol. The new study looked at cocoa’s effect on blood vessel dilation, a key indicator of vessel health.

People with diabetes who were between 50 and 80 years old took part in the two-part study. First, 10 people were given cocoa drinks with low (75 mg), medium (371 mg), or high (963 mg) flavanol concentrations on three different occasions to determine safety and optimal dose. Second, 41 people were given either a high-flavanol cocoa (321 mg per serving) or a similar tasting drink with a negligible amount of flavanols (control drink) three times per day for 30 days. Blood vessel dilation and blood levels of flavanols were measured to assess the response to the cocoa drinks.

A sweet success story

All the people who drank the high-flavanol cocoa beverage in both parts of the study, had significant improvements in blood vessel dilation compared with baseline measurements, without any side effects.

The same effect was seen after 30 days, suggesting that cocoa’s effect didn’t wear off after repeated use. Cocoa actually reversed blood vessel damage after 30 days, so that measurements of blood vessel function were comparable to those of healthy people of the same age. The drink containing the lowest amount of flavanols did not improve vessel dilation and neither did the control drink.

“The degree of reversion of (blood vessel) dysfunction was comparable to the reported degree of improvement observed after using controlled exercise or the administration of [drugs], including insulin,” said the study’s authors. “Assuming that improvement of blood vessel dysfunction is associated with better cardiovascular prognosis, the regular intake of flavanol-containing cocoa should produce similar effects.”

Note that flavonal content varies among products and the way flavonols are metabolized may be influenced by other substances in the body, so results may vary. And since many chocolate products are high in sugar, fat, and calories, chocolate lovers with diabetes should keep in mind that reducing or preventing overweight and obesity is an important part of managing diabetes and heart health.

(J Am Coll Cardiol 2008;51:2141–9)

Kimberly Beauchamp, ND