Chocolate May Cut Common Disease Risk, Nutrition Scientists Claim

Eating five or more servings of chocolate per week was found to be linked to a 10 percent lower risk of developing type 2 diabetes, according to a study published on Wednesday. "Chocolate, particularly dark chocolate, is rich in bioactive compounds called flavonoids, such as flavan-3-ols, which have been shown to improve insulin sensitivity," study lead author Binkai Liu told Newsweek. "These mechanisms may contribute to better blood sugar regulation and a lower risk of type 2 diabetes among those who consume dark chocolate in moderation." Type 2 diabetes is a metabolic disease that affects approximately 11.6 percent of the U.S. population, according to the Centers for Disease Control and Prevention—and more than a third of American adults are believed to have prediabetes, otherwise known as insulin resistance. The disease involves the malfunctioning of the hormone insulin, which is meant to process sugar in the body, taking it out of the bloodstream to be used elsewhere as energy. Nutrition scientists at Harvard University's T.H. Chan School of Public Health found that eating at least five weekly servings of dark chocolate was associated with a 21 percent lower risk of type 2 diabetes, compared to those who rarely or never ate chocolate. But eating more milk chocolate was not associated with lower diabetes risk, instead linked with long-term weight gain, a risk factor for type 2 diabetes. "Dark chocolate contains a higher cocoa content, which is the source of beneficial flavonoids," explained Liu. "Milk chocolate, on the other hand, often has lower cocoa content." These findings were based on data from 192,000 adults who were studied for 30 or more years in the Nurses' Health Studies and Health Professional Follow-up Study, from 1986 to 2021. They were all free from diabetes at the start of the study and reported on their food habits, diabetes status and body weight as the years went on, during which nearly 19,000 participants reported being diagnosed with type 2 diabetes. "We hope readers take away the message that small dietary choices, like incorporating flavonoid-rich foods such as dark chocolate, can potentially support metabolic health when consumed in moderation," said Liu. "However, it's important to view these findings within the context of an overall balanced diet and healthy lifestyle. Dark chocolate is not the solution to diabetes, but moderation and balance is key."

The study, which was published online in the British Medical Journal on Wednesday, has already been met with a mixed reaction by the scientific community. Professor Baukje de Roos, from the Rowett Institute at the University of Aberdeen, said in a statement: "As dark chocolate has a much higher cocoa content, this means that bioactive compounds in cocoa, and in dark chocolate, such as flavanols, may contribute to the lowering of diabetes risk, possibly by increasing insulin sensitivity. "However, if and how flavanols on their own reduce diabetes risk remains to be established; a recent large-scale randomized controlled trial (the COSMOS study) found that cocoa flavanol supplements did not affect the risk of type 2 diabetes." Professor George Davey Smith, an epidemiologist at the University of Bristol, went further, stating: "At the risk of being a Grinch at Christmas, it has to be said that this is, frankly, a meaningless paper." He said that the scientists' findings reflected "residual confounding and selection bias" caused by the fact that higher-income, wealthier and healthier groups tend to consume dark chocolate, and milk chocolate tends to be eaten by the less well-off. However, Liu told Newsweek: "While we cannot completely rule out the influence of other factors, our analyses accounted for many potential confounders, including overall dietary quality and socioeconomic status, and the results stayed robust after these sensitivity analyses." Do you have a tip on a food story that Newsweek should be covering? Is there a nutrition concern that's worrying you? Let us know via science@newsweek.com. We can ask experts for advice, and your story could be featured in Newsweek.

Reference

Liu, B., Zong, G., Zhu, L., Hu, Y., Manson, J. E., Wang, M., Rimm, E. B., Hu, F. B., Sun, Q. (2024). Chocolate intake and risk of type 2 diabetes: prospective cohort studies, BMJ 387: e078386. https://doi.org/10.1136/bmj-2023-078386