By Alimat Aliyeva

A new study conducted by the Department of Nutrition at the Harvard T.H. Chan School of Public Health has shown that eating dark chocolate, rather than milk chocolate, is associated with a reduced risk of type 2 diabetes (T2D). This result is considered a significant breakthrough in the field of nutrition and health.

The lead author of the study, graduate student Binkai Liu from the Department of Nutrition, said, "Our results show that not all chocolates are the same."

According to Liu, there are significant health differences between dark and milk chocolate consumption. He added that this finding is an important signal for chocolate lovers: choosing dark chocolate over milk chocolate may be more beneficial to health.

The study used data from two major medical surveys — the Nurses' Health Study I and II — as well as a follow-up study of medical professionals. For over 30 years, 192,000 non-diabetic adult participants tracked their eating habits, including chocolate consumption, and the development of diabetes. During this period, 19,000 participants were diagnosed with T2D. Among the 112,000 people who reported consuming chocolate, including both dark and milk varieties, approximately 5,000 were diagnosed with T2D. This large sample size provided a solid foundation to compare the effects of different types of chocolate on diabetes risk.

The researchers found that participants who consumed at least five servings of any type of chocolate per week had a 10% reduced risk of developing T2D compared to those who rarely consumed chocolate. Dark chocolate had an even greater effect: those who ate at least five servings of dark chocolate per week had a 21% lower risk of developing T2D. For every additional serving of dark chocolate, the risk decreased by 3%. On the other hand, milk chocolate consumption did not reduce the risk of T2D, but was instead associated with long-term weight gain. This difference is attributed to the positive health effects of the polyphenols found in dark chocolate.

Qi Sun, associate professor of Nutrition and Epidemiology and corresponding author of the study, said that the clear distinction between the effects of dark and milk chocolate on diabetes risk and long-term weight management was surprising. Although dark and milk chocolates contain similar amounts of calories and saturated fats, the polyphenols in dark chocolate appear to counteract the negative effects of sugar and saturated fats, he explained. However, additional research is needed to confirm these findings.

The study was funded by several grants from the U.S. National Institutes of Health. This research provides new insights into the relationship between chocolate consumption and the risk of T2D. The results suggest that the polyphenols in dark chocolate may aid in weight management and reduce the risk of diabetes. However, the authors noted that participants’ chocolate consumption was relatively low compared to national averages, and these findings may not apply to individuals who consume chocolate in larger quantities.

This study contributes important new evidence to the growing body of research on the health benefits of dark chocolate, offering valuable insights for public health policymakers. The researchers emphasize the need for further investigation in this area to better understand the long-term effects of chocolate on health.