Dark chocolate and type 2 diabetes| Medical News Bulletin

Could your dark chocolate dependence protect against diabetes? According to a
new article published in the BMJ, that sweet tooth may finally come in handy.¹ Sitting at a
staggering 462 million, the global burden of type 2 diabetes continues to grow,² and
while we know that lifestyle changes can help, tackling the issue at a population level
has proven tricky. ³ Scientists based at Harvard’s T.H. Chan School of Public Health may have identified an appetizing advancement. These Boston boffins claim that when it comes to dark chocolate, a little bit of what you fancy can do you good. But before you run out to raid the Easter chocolate sale shelves, let’s take a moment to get our teeth into the evidence. Is there a relationship beteween dark chocolate and type 2 diabetes?

Is there a link between chocolate and type 2 diabetes?

In their recently published article, researchers describe the results of a huge prospective cohort study. The team got permission to comb through three huge existing US data sets: Nurses’ Health Study (NHS), Nurses’ Health Study II and the Health Professionals Follow-Up Study.^{1, 4, 5, 6} These cohort studies followed the participants for decades, starting in 1976, collecting background information on factors such as their age, BMI, diabetes status and, of course, chocolate consumption.

For nearly 50 years, over 190,000 female nurses, and from 1986 onwards, male health professionals, regularly filled out questionnaires about their health and habits. Respondents answered many questions about their diet, including how often they consumed different types of chocolate.

The T.H. Chan School of Public Health investigators used this data to figure out whether people who ate chocolate were more or less likely to develop type 2 diabetes later in life, and whether the type of chocolate you eat influences your chances.

The study reported that people who ate more than five servings of dark chocolate
per week had a 21% lower risk of developing T2D. The benefits were also more
apparent among those younger than 70, male participants, those with higher
physical activity, and those with no family history of diabetes.

However, these results didn’t translate to other chocolate subtypes. Instead, the researchers found no TD2 benefit in high-milk chocolate consumers. They did, on the other hand, see a link between milk chocolate consumption and long-term weight gain. ¹

Sweet, sweet science

Although the study didn’t investigate the underlying science behind this benefit, other
research has offered possible explanations and what gives dark chocolate the edge over milk chocolate?

Cocoa is high in flavan-3-ols, a bioactivecompound linked to improved glucose metabolism and reduced risk of T2D.⁷ Dark chocolate’s cocoa content can range up to as high as 90%. Milk chocolate, in contrast contains much less cocoa and has a higher added sugar content.⁸ The extra flavanoid content in dark chocolate packs a serious antioxidant punch. The difference in sugar content and flavan-3-ol could explain why milk chocolate is a no-no for diabetes defence and instead leads to weight gain. ⁹

Weighing the evidence

As Carl Sagan said, ‘Extraordinary claims require extraordinary evidence’ and at first glance claims that chocolate is good for you sound pretty extrodinairy. So how good is the evidence?

This study was the first to investigate whether different chocolate subtypes protect
against diabetes. ¹ Before this, scientists suspected the protective role of flavan-3-ols
in chocolate, but they hadn’t confirmed whether this differed between dark and milk
variations. Without data on the sub-type of chocolate the health care workers had been eating, the unhealthy effects of milk chocolate mask any beneficial boosts coming from dark chocolate. The especially detailed data collection by the Nurse’s Health Survey allowed the dark chocolate detectives to spot patterns that would usually stay hidden.

There was one noticeable flaw in the study’s questionnaire, however. The
cocoa content of dark chocolate can vary significantly, ranging from 50 to 90%. As
the survey did not ask about cocoa content or the size of servings, just how many, it is challenging to draw definite conclusions here.

The large sample size is also a strong asset to this report, however, we must also
question how relevant the findings are to the general public. As previously
mentioned, these cohorts included only healthcare professionals. ^{4, 5, 6} In general, the
healthcare profession is a highly active field, with people spending a lot of time on
their feet. This is important as physical activity lowers the risk of T2D. ¹⁰ So, this begs
the question, would we receive the same results if we surveyed office workers sitting
behind a desk all day? It is difficult to say with the current data.

The authors didn’t tell us how dark chocolate compared to eating fruit that was high in flavan-3-ols, for example grapes or cherries either.

Food for thought

It appears that flavonoid-rich food such as dark chocolate may reduce T2D risk.
However, more research is needed to replicate these results in the general public. In
particular, the study’s authors advised that randomised control trials will be the next
step forward, so watch this space! To conclude, although enticing, perhaps think
twice before switching out your dates for dark chocolate!

References

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