Sweet Lies: Can Dark Chocolate Save You from Diabetes?

We eat 1.28 billion kilograms of chocolate in the US annually, generating revenues of $23 billion. There are three forms of chocolate.

• Dark Chocolate has the highest cacao content, the richest in flavan-3-ols, and the lowest sugar content. It represents about 20% of sales.
• Milk Chocolate with about half as much cocoa, 6-fold less flavan-3-ols, and a higher sugar content. It represents about 80% of sales.
• White Chocolate, the edible fat extracted from the cocoa bean, contains no cocoa or flavan-3-ols and has the highest sugar content. It is used as an ingredient rather than as a standalone snack.

The rising tide of “food as medicine” asks, once again, whether chocolate is associated with the risk of Type 2 diabetes (T2D). A new article in the BMJ offers its opinion based on three large prospective studies, the Nurses’ Health Study (NHS), I and II, and the Health Professionals Follow-Up Study (HPFS), with roughly 190,000 participants, primarily women. 

Consumption of chocolate was assessed using our old friend, the food frequency questionnaire (FFQ), every four years. The use of the FFQ points to the first weakness in the study as the researchers report that the correlation coefficient, a measure of the strength of the relationship, between contemporaneous diet records and FFQ were roughly .6 for dark chocolate and .4 for milk chocolate, on a scale of 0 to 1.

Type 2 diabetes was self-reported and then confirmed by physicians, and weight changes over time were also self-reported. The correlation between reported and actual body weight was roughly .9. Besides quantifying chocolate intake across nine levels (from none to >6 ounces a day), participants were asked whether they were eating dark or milk chocolate. 

Across all three cohorts, higher chocolate intake was linked to increased energy, saturated fat, and added sugar consumption—however, dietary patterns varied by chocolate type. Dark chocolate intake was associated with healthier dietary behaviors, including higher adherence to the Alternate Healthy Eating Index (AHEI), greater consumption of fruits, vegetables, epicatechin, and total flavonoids, including higher intakes of flavan-3-ol-rich foods and drinks, such as blueberries, tea, and red wine.

In contrast, milk chocolate consumption showed inverse associations with these variables and stronger positive links to less healthy foods and nutrients, such as saturated fat, added sugar, red and processed meat, and sweets. 

This points to the second weakness of the study. Even if we take self-reported FFQ consumption as truth, eating dark or milk chocolate comes with many confounding factors – especially the consumption of flavan-3-ol-rich foods and drinks, which has been associated with a decreased risk of type 2 diabetes. The value of dark vs. milk chocolate in this study is in discriminating between flavan-3-ol-rich diets; it is a biomarker more than a variable. Keep this in mind as we consider the findings on the incidence of diabetes.

While the pooled data found no significant association between total chocolate consumption and the onset of type 2 diabetes, the higher consumption of dark chocolate (>5 ounces per week) lowered the risk of diabetes by 21%. In comparison, Milk chocolate consumption showed no significant associations with T2D risk – up or down

Age, sex, BMI, physical activity, AHEI, and family history of diabetes did not significantly influence the relationship between total or milk chocolate consumption and the risk of T2D. However, the impact of dark chocolate on T2D was enhanced by a higher-quality diet, greater physical activity, and no family history of T2D. Despite a reductionist desire to identify the single factor improving our health, especially when it comes to a treat like chocolate, dark chocolate remains the marker of a host of healthier behaviors. 

Increased intake of total chocolate was associated with long-term weight gain. For those already obese (BMI ≥30) vs those more sveldt (BMI <25), milk chocolate resulted in a doubling of the weight gain from 0.33kg to 0.68kg (a bit more than a pound). Dark chocolate intake did not reflect weight gain. However, before rushing out for that dark chocolate preventative care, we should remember that it wasn’t the dark chocolate alone; there was also that pesky additional physical activity and healthier food choices. 

“The findings of the present study showed that higher consumption of dark, but not milk, chocolate was associated with a lower risk of T2D.”

That is correct, but as we have seen, it is an incomplete statement. The researchers may find satisfaction in a media environment that favors the sound bite and an academic tenure system that rewards publications and media citations. But by failing to deliver on the nuance, by pretending that dark chocolate has some self-contained mystical property, they fail the public health and perpetuate confusion and, dare I say, misinformation.   

To be fair, they do know that dark chocolate is not the answer. They write,

“Dark chocolate, with a higher cocoa content than milk chocolate, may lower the risk of T2D through various mechanisms…. although dark chocolate contains similar levels of energy and saturated fat to milk chocolate, the rich polyphenols in dark chocolate might offset the effects of saturated fat and sugar on weight gain and the risk of other cardiometabolic diseases.”

Burying that statement two paragraphs before the end of the paper is not a public good. Not adding that dark chocolate was associated with a healthier diet and more physical activity fails to tell the whole story.

While the study suggests a tantalizing 21% reduction in T2D risk with dark chocolate, let’s not kid ourselves. This isn’t about chocolate’s superpowers; it reflects better diets, more exercise, and fewer Twinkies. If you’re chasing health, don’t just unwrap a bar of dark chocolate—unwrap a healthier lifestyle while you’re at it.

Source: Chocolate intake and risk of type 2 diabetes: prospective cohort Studies BMJ DOI: 10.1136/ bmj‑2023‑078386