Dark chocolate reduces type 2 diabetes risk

US cohort study highlights dark chocolate’s potential role in reducing type 2 diabetes risk, while milk chocolate consumption is associated with weight gain.

Study: Chocolate intake and risk of type 2 diabetes: prospective cohort studies. Image Credit: Ahmet Misirligul/Shutterstock.com

In a recent study published in BMJ, researchers investigated the link between consumption of total milk and dark chocolate consumption and the risk of developing type 2 diabetes (T2D) across three cohorts in the United States.

Their findings indicate that dark chocolate consumption may lower the risk of developing T2D, and milk chocolate, while it does not affect T2D risk, is associated with increased weight.

Background

Globally, the prevalence of T2D has risen sharply; researchers estimate that 463 million people were affected in 2019, a number which is expected to grow to 700 million in 2045.

This condition involves insulin resistance and impairments to insulin secretion, often leading to complications, including vision loss, kidney failure, and heart disease.

Experts have shown that lifestyle factors, particularly healthy diets, play an important role in preventing T2D and managing the disease in people who have already developed it.

Consuming higher amounts of flavonoids from food sources such as chocolate may reduce the risk of developing T2D, as they have vasodilatory, antioxidant, and anti-inflammatory effects that can improve cardiometabolic health.

About the study

In this study, researchers investigated whether consuming different forms of chocolate varying in their content of milk, sugar, and cocoa, such as white, milk, and dark, affects the risk of developing T2D and changes in body weight, which is an established risk factor for T2D.

The three cohorts comprised 121,700 women from 1976, 116,340 women from 1989, and 51,529 men from 1986. Individuals with cancer, high energy intake, cardiovascular disease, and diabetes, as well as those with missing data, were excluded from the dataset.

Diet, including chocolate consumption, was assessed every four years using validated questionnaires and used to calculate nutrient intake.

The incidence of T2D came from self-reported data that was confirmed using medical records and other questionnaires. Symptoms of the condition, intake of hypoglycemic medication, and fasting glucose levels were used for diagnosis.

Weight was self-reported and subsequently validated, and weight changes were calculated for the four-year intervals between survey rounds.

Researchers used statistical models to calculate the risk of developing T2D and adjusted their analyses for family history of the disease, physical activity, body mass index (BMI), and ethnicity. They also conducted analyses separately for various subgroups and used sensitivity tests to validate their findings.

An additional analysis considered the relationship between the consumption of chocolate and changes in weight (adjusting for BMI at baseline, energy intake, physical activity ethnicity, and age).

Findings

The study included 192,208 individuals from three cohorts, with most participants being non-Hispanic White. Higher chocolate intake was linked to higher consumption of added sugar, saturated, and higher overall energy.

The consumption of dark chocolate showed positive correlations with better dietary quality, including greater intake of flavonoids, vegetables, and fruits. Conversely, milk chocolate consumption is correlated with higher consumption of sugar and saturated fats and overall poorer diet-related choices.

Overall, people who consumed more than five servings of any chocolate each week had a 10% lower risk of developing T2D, with each additional serving reducing their risk by 1%.

For dark chocolate, consumption of more than five servings per week lowered the risk of T2D by 21%, representing a significant linear reduction.

In the subgroup analysis, higher diet quality enhanced the association between dark chocolate consumption and the risk of T2D, with the reduction in risk increasing to 34% for people with high-quality diets.

People without a family history of the condition and those who were more physically active, male, or younger were also more likely to experience the benefits of dark chocolate consumption.

Milk chocolate consumption was not significantly associated with the risk of T2D but did lead to greater weight gain. Individuals with obesity gained more weight from the consumption of milk chocolate than those with lower BMI.

Conclusions

This study’s findings align with previous research, showing that overall chocolate intake is associated with a lower risk of T2D. Dark chocolate may have additional benefits because it contains higher levels of cocoa and healthy compounds, as well as less sugar compared to milk chocolate.

These compounds, such as epicatechin, can reduce inflammation, reduce oxidative stress, increase glucose metabolism, and trigger improvements in insulin sensitivity.

While this study distinguished between different types of chocolate and considered long-term effects on health, its findings are not generalizable to non-White populations.

Notably, chocolate consumption among the cohorts considered was lower than national averages. Further research on more diverse groups is needed to validate these findings.