Qi Sun of Harvard Medical School and colleagues from China and the United States conducted a prospective cohort study and concluded that dark (but not milk) chocolate consumption is associated with a reduced risk of developing type 2 diabetes. The analysis included more than 190,000 participants in the NHS (1986–2018), NHSII (1991–2021), and HPFS (1986–2020) cohorts who were free of diabetes, cardiovascular disease, and cancer at enrollment. The total follow-up period was more than 4.8 million person-years. The results were published in The BMJ.
During the follow-up period, type 2 diabetes developed in nearly 19,000 participants. After adjusting for individual risk factors, lifestyle, and diet, those who consumed at least five servings of any chocolate per week had a 10 percent lower incidence of the disease (95 percent confidence interval 2–17) than those who rarely or never ate it (p = 0.07 for trend). Analysis by type of chocolate revealed a similar association only for dark chocolate—a 21 percent lower incidence (95 percent confidence interval 5–34, p = 0.006 for trend), but not for milk chocolate. Moreover, the amount of dark chocolate consumed and the risk of diabetes showed a linear relationship: an increase of one serving per week was associated with a 3 percent lower incidence (95 percent confidence interval 1–5). Furthermore, consumption of milk chocolate, but not dark chocolate, was positively correlated with weight gain.
