Qi Sun from Harvard Medical School and colleagues from China and the US 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 did not have diabetes, cardiovascular disease, or cancer at the time of inclusion. The total follow-up period was more than 4.8 million person-years. The results were published in The BMJ.
During the observation period, type 2 diabetes developed in almost 19,000 participants. After adjustment for individual risk factors, lifestyle, and diet, it turned out that 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 ate it or did not eat it at all (p = 0.07 for trend). Analysis by individual types of chocolate revealed a similar association only for dark chocolate — by 21 percent (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 decrease in the incidence (95 percent confidence interval 1–5). At the same time, the consumption of milk chocolate, but not dark chocolate, was positively correlated with weight gain.
