Eating dark, but not milk, chocolate may be associated with a lower risk of developing type 2 diabetes.

Liu B, Zong G, Zhu L, et al. Chocolate intake and risk of type 2 diabetes: prospective cohort studies. BMJ. 2024;387:e078386.

 

Research published in The BMJ found that those who ate at least five servings of dark chocolate per week had a 21% lower risk of developing type 2 diabetes compared with those who never or rarely ate dark chocolate.

“Our findings suggest that not all chocolate is created equal,” Binkai Liu, lead author of the study and a doctoral student at the Harvard Kenneth C. Griffin Graduate School of Arts and Sciences, studying in the Harvard T.H. Chan School of Public Health’s Department of Nutrition, said in a press statement.

Brownstein M. Eating dark chocolate linked with reduced risk of type 2 diabetes. Harvard T.H. Chan School of Public Health. December 6, 2024.

 

For anyone who loves chocolate, this is a reminder that making small choices, like choosing dark chocolate over milk chocolate, can make a positive difference to their health.

While some research has examined the association between chocolate and type 2 diabetes, the conclusions have been inconsistent, and many studies didn’t differentiate between types of chocolate like milk and dark.

Liu B, Zong G, Zhu L, et al. Chocolate intake and risk of type 2 diabetes: prospective cohort studies. BMJ. 2024;387:e078386.

 

To explore this, the researchers examined data from three large studies. These included the Nurses’ Health Study and Nurses’ Health Study II, as well as the Health Professionals Follow-Up Study. The studies ran for more than 30 years and involved a total of more than 289,500 adults who did not have diabetes at the time the studies began.

Throughout the study, participants self-reported their eating habits, body weight, diabetes status, and chocolate consumption.)

 

Not all chocolate is created equal

 

For each serving of dark chocolate eaten per week, a 3% reduction in risk was observed. The same reduction was not found for milk chocolate.

Instead, increased consumption of milk chocolate was associated with long-term weight gain.

“We were surprised by the clear split between dark and milk chocolate’s impact on diabetes risk and long-term weight management,” Qi Sun, MD, co-author of the study and an associate professor in the Departments of Nutrition and Epidemiology, said in a press statement.

Brownstein M. Eating dark chocolate linked with reduced risk of type 2 diabetes. Harvard T.H. Chan School of Public Health. December 6, 2024.

 

 

Chocolate should be eaten in moderation

 

Marilyn Tan, MD, an endocrinologist and Clinical Associate Professor of Medicine at Stanford University School of Medicine, says that while the findings are important, chocolate should still be consumed mindfully.

“To reduce relative risk for type 2 diabetes by 10% is significant and meaningful. Based on this study, dark chocolate is probably better than milk chocolate, but it's important to keep in mind that all chocolate should be consumed in moderation,” she tells MDLinx.

“It's not so much a concern about the cacao as what comes with it (ie, sugar). In my mind, chocolate doesn't necessarily need to be 100% off-limits for people with diabetes, but it's important to limit the amount consumed, and, if someone has diabetes, to cover for it with medications/insulin if needed. For a diet to be successful, it has to be sustainable, and if that includes occasionally having a small square of chocolate, it's unlikely to hurt.”

 

The benefits of dark chocolate

 

The research published in The BMJ is the latest to examine the relationship between chocolate and type 2 diabetes risk. Dr. Tan says it is likely that numerous factors could contribute to the benefits of dark chocolate.

“For many years, there has been an interest in the benefits of dark chocolate, and many studies have shown the benefits of dark chocolate. It's not surprising that milk chocolate was not associated with a similar reduced risk since milk chocolate usually has more sugar. It's also possible that when people consume dark chocolate, they are consuming them with foods/drinks different from [those] consumed with milk chocolate, so it's likely there's more to it than just the type of chocolate. In addition, dark chocolate has more dietary flavonoids,” she says.

 

Dietary flavonoids and diabetes risk

 

A higher consumption of flavonoids has been found to decrease risk of type 2 diabetes. Flavonoids can be found in fruits and vegetables. Chocolate is made from beans from the cacao tree and is one of the most flavanol-rich foods.

Liu B, Zong G, Zhu L, et al. Chocolate intake and risk of type 2 diabetes: prospective cohort studies. BMJ. 2024;387:e078386.

 

Research suggests that a diet that includes fresh fruits and vegetables, whole grains, fish, lean dairy, and nuts can reduce the risk of type 2 diabetes.

Basiak-Rasała A, Różańska D, Zatońska K. Food groups in dietary prevention of type 2 diabetes. Roczniki Państwowego Zakładu Higieny. 2019;70(4):347–357.

By comparison, processed and red meats, sugar-sweetened beverages, and refined grains increase risk.

 

“Food has a significant impact on the risk of type 2 diabetes. Weight gain from high-calorie foods is associated with a higher risk of diabetes, and consumption of highly processed foods and high sugar content is also associated with a higher risk of type 2 diabetes. Even in someone with established prediabetes or diabetes, dietary content makes a significant impact on glucose control. Certain foods will drive up glucose, while others may not cause such a rise in glucose,” Dr. Tan says.

“We know that increased consumption of fiber, fresh produce, and lean protein can help reduce diabetes risk. Some of it is the food content itself—fiber, vitamins, minerals—and some of it is the macronutrient composition: more protein, fewer carbohydrates.  We also know it's not just the types of foods, but also how they are prepared, and the less processed a food is, the better.”