Dark Chocolate Linked to Lower Risk of Type 2 Diabetes, Study Finds

Americans love chocolate and climbing food costs have not affected this love affair. The National Confectioners Association reports that even with the increase in food costs, Americans spent $21.4 billion on chocolate in 2024.[1] So, a new study on the health benefits of dark chocolate should warm the hearts of our chocolate-loving society.

Recently announced by Harvard T.H. Chan School of Public Health, the new study[2] suggests that dark chocolate might reduce the Type 2 diabetes risk by as much as 21%.  The study was published online December 4 in The BMJ, formerly the British Medical Journal.

Dark chocolate study

While there have been earlier studies on the relationship between chocolate and Type 2 diabetes, the findings were inconsistent. Also, few studies differentiated between chocolate subtypes, or dark versus milk. Harvard researchers wanted to investigate the associations between dark, milk and total chocolate consumption and Type 2 diabetes risk in three US groups.

Researchers used data from the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study, which included data from 192,000 adult participants over the course of 30+ years who were diabetes free at the start. Participants reported on their food habits, including chocolate consumption, as well as their diabetes status and body weight.

By the end of the study period, nearly 19,000 of the total participants reported being diagnosed with Type 2 diabetes. Of the nearly 112,000 who reported specifically on their dark and milk chocolate intake, nearly 5,000 were diagnosed with Type 2 diabetes.  

Study findings about dark chocolate

The study found that participants who consumed at least five ounces of any type of chocolate per week had a 10 percent lower Type 2 diabetes risk compared to those who never or rarely consumed chocolate. Dark chocolate had an even bigger impact: Participants who consumed at least five servings of this chocolate per week showed a 21 percent lower Type 2 diabetes risk.

Researchers also observed a 3 percent reduction in risk for every serving of dark chocolate consumed per week. Consumption of milk chocolate, meanwhile, was not associated with reduced Type 2 diabetes risk. Also, increased consumption of milk chocolate, but not dark chocolate, was associated with long-term weight gain, a potential contributor to the development of Type 2 diabetes.

Researchers said of the findings, even though dark and milk chocolate both have similar levels of calories and saturated fat, the rich polyphenols (plant compounds that have antioxidant and anti-inflammatory properties) in dark chocolate might offset the effects of saturated fat and sugar on weight gain and diabetes.

The study authors also pointed out that chocolate consumption of participants was low compared to recorded national averages. For this reason, the findings might not apply to individuals whose chocolate consumption was high.

Researchers said that further research, especially randomized controlled trials among middle aged participants and of longer duration, is needed to confirm these findings.

Other health benefits of dark chocolate

The Harvard study is not the first showing the benefits of dark chocolate. Studies have shown that dark chocolate may be beneficial in reducing the risk of heart and cardiovascular disease. Other studies suggest that moderate amounts of dark chocolate may reduce insulin resistance and improve insulin sensitivity (the body’s ability to effectively respond to insulin) due to the flavonoids (naturally occurring compounds in many plants with antioxidant and anti-inflammatory properties) in cocoa.