Over the years, studies have attempted to back up the purported health benefits of indulgent foods and drinks like red wine and chocolate. A new study out of Harvard University shows some promising news for chocolate lovers, but it depends on what kind of chocolate you like.

The research, published Dec. 4 in the British Medical Journal, found that eating dark chocolate was associated with a lower risk of developing type 2 diabetes. That doesn't hold true for milk chocolate, however. It's one of the few studies of its kind to specifically compare milk and dark chocolate, and also one of the largest studies on the topic to date.

To reach their conclusions, the scientists analyzed the health data of roughly 192,000 men and women in the U.S. who were followed for a period of more than 30 years and regularly answered questions about things like their diet, weight, and physical activity. The team found that people who ate least five ounces of dark chocolate per week-or five servings-had a 21 percent lower risk of developing type 2 diabetes compared to those who rarely or never ate dark chocolate. The risk of developing diabetes fell by three percent for every ounce of dark chocolate consumed.

Meanwhile, milk chocolate seemingly had no metabolic health benefits, and actually proved harmful to health. The more people consumed milk chocolate throughout the study, the likelier they were to gain weight, especially if they were already obese.

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Past studies have shown that dark chocolate can reduce inflammation and improve insulin sensitivity, which could be a result of the food's lower sugar content and higher levels of polyphenols. Other studies have found that eating chocolate is associated with a lower risk of developing type 2 diabetes; two found that eating dark chocolate every day for two weeks lowered participant blood pressure, improved their insulin sensitivity, and improved a number of cardiovascular and metabolic health markers when compared to those who ate white chocolate.

"In general, polyphenols have been demonstrated to be beneficial for diabetes biomarkers in randomized controlled trials," study lead author Binkai Liu told The Washington Post. "That's well established."

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Still, Liu cautioned that this doesn't mean you should binge eat dark chocolate for your health, as the studies imply correlation but not causation.

"We can't say for certain that eating dark chocolate will lower your risk of type 2 diabetes," Liu said. "We can say that eating it is associated with a lower risk. But we don't want people to overinterpret the results."

"The key message is balance but not excess," she added. "The important thing to prioritize in your diet is nutrient-rich foods."

As always, consult your doctor to assess your diabetes risk and possible prevention plans.