Dark chocolate trumps milk chocolate (and no chocolate) in this new study. Depositphotos. –
In new analysis out of the Harvard T.H. Chan School of Public Health, US and Chinese scientists have determined that eating five servings of dark chocolate a week could reduce your risk of type 2 diabetes by 21%, compared to those who abstained completely or rarely indulged.
What’s more, fans of milk chocolate did not share in the same potential benefits – in fact, they were more likely to have negative health outcomes.
“Intake of milk, but not dark, chocolate was positively associated with weight gain,” noted the researchers in the paper. “Compared with those who did not change their chocolate intake, increased intake of milk chocolate over four-year periods was associated with 0.35 kg [12 oz] more four-year weight gain over time. Increasing dark chocolate intake was not associated with weight change over time.”
The researchers assessed questionnaires answered by 111,654 female nurses and male healthcare professionals selected from the extensive Nurses’ Health Study (NHS; 1986-2018), Nurses’ Health Study II (NHSII; 1991-2021) and Health Professionals Follow-Up Study (HPFS; 1986-2020). They excluded anyone with diabetes, cardiovascular disease or cancer at baseline, as well as those with missing chocolate data, or who had unusually high or low energy intake. A secondary analysis of bodyweight changes excluded participants on the same basis.
Then, adjusting for risk factors associated with personal, lifestyle and diet, the researchers – looking at data spanning a quarter of a century – found that type 2 diabetes prevalence was lowest in those who ate five servings of dark chocolate a week.
In the initial analysis of 192,208 participants who ate any kind of chocolate, 18,862 were found to have developed type 2 diabetes over the course of the studies. This was roughly a 10% lower risk of developing the condition than non-chocolate eaters. However, when the secondary analysis was done – assessing those who said they ate dark chocolate versus other kinds like milk blends – the health benefits swung towards the dark-chocolate cohort. And, in this analysis, there was no discernible advantage to eating just milk chocolate.
According to the National Health and Nutrition Examination Survey (2007-08 and 2013-14), 11.1% of US adults ate chocolate regularly, but only 1.4% went for dark (products that had 45% or more cocoa content). Keep in mind that one serving is equal to a standard chocolate bar, or 29 g (1 oz)).
And, given its nature as an observational study, there are limitations – overall, younger people ate more dark chocolate, and data was self-reported by participants.
However, the researchers pooled data from previous dark-chocolate-specific studies to bolder their findings. One such trial, a 15-day randomized control trial on glucose intolerance, hypertensive patients who consumed 100 g (3.5 oz) high-polyphenol dark chocolate each day had a significant reduction in blood pressure and better insulin sensitivity, compared to a control group that ate 90 g (3.2 oz) of white chocolate in the same time frame.
“Studies examining the consumption of high versus low flavanol cocoa products also showed health benefits in improving insulin resistance among individuals with overweight and obesity, increasing high density lipoprotein cholesterol levels, and lowering blood pressure among patients with diabetes,” the researchers added.
Flavanols, a polyphenol antioxidant – compounds also prevalent in fruit and vegetables – are linked to better heart health and lower type 2 diabetes risk. Dark chocolate with 50-80% cacao has the highest flavan-3-ol content with 3.65 mg/gm, while on average 35%-cocoa milk chocolate has 0.69 mg/g. White chocolate has none.
Previous studies into flavan-3-ol has shown evidence of its antioxidant, anticarcinogen, cardiopreventative, antimicrobial, anti-viral, and neuro-protective agents. While this type of polyphenol is ideally obtained through unprocessed means like fruit and vegetables, its presence in dark chocolate may help offset the negative aspects of milk chocolate. The researchers noted that while dark chocolate has a comparative energy and saturated fat makeup to milk varieties, its polyphenols may alter how the body metabolizes this sugar and fat and, as a result, negate weight gain and help lower cardiometabolic disease risk factors.
Earlier research has also found that dark chocolate has a positive impact on gut flora populations that play key roles in maintaining metabolic health.
“It has been suggested that bioactive compounds in cocoa, such as flavan-3-ols and their monomeric form, epicatechin, mitigate risk of type 2 diabetes by improving insulin sensitivity, protecting pancreatic β cells from oxidative stress, lowering pro-inflammatory cytokines such as tumor necrosis factor-α and IL-6, and improving endothelial function by stimulating the production of nitric oxide, a vasodilator, which may lead to improved glucose metabolism and reduced risk of type 2 diabetes.”
Milk chocolate, as almost any sweet tooth would know, has higher added sugar content, which, the researchers point out, is “an established dietary risk factor for cardiometabolic diseases.”
“These findings were independent of established and potential risk factors for diabetes and were robust in multiple sensitivity analyses,” the researchers noted. “Increased consumption of dark, but not milk, chocolate was associated with lower risk of type 2 diabetes. Increased consumption of milk, but not dark, chocolate was associated with long term weight gain.”
While the study shows a fairly robust association between health and dark chocolate consumption, it’s not causal. Further clinical trials are needed to better understand and assess the potential mechanisms at work.
The study was published in the journal the BMJ.
Source: Harvard T.H. Chan School of Public Health
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