Life is Like a Box of Confusion - New Study on Chocolate vs Diabetes

We break down the big new study on Chocolate and Type 2 Diabetes Risk. If you want "ignorance is bliss," this is not the letter for you.

Does chocolate really prevent diabetes? This question has at the top of minds since a major publication in the BMJ claiming a 21% reduction in type 2 diabetes (T2D) risk in those who ate at least 5 servings of Dark Chocolate per week.

Chocoholics Rejoice! …

Maybe.

Just how legitimate are the findings?

We’re going to go over the study, and I’ll explain why the findings aren’t all they’re chalk-olated up to be. But I won’t leave you high and dry. I’ll also suggest how to get the most health bang for your chocolate buck, with science and practical tips.

I now also have a video covering this content. If you prefer to watch, click below. Otherwise, read onward!

The New Chocolate Study

First, let’s break down what they did in this study. This was a large-scale observational study where they looked at associations between chocolate intake and the development of T2D over three cohorts:

• Nurses’ Health Study (NHS)

• Nurses’ Health Study II (NHSII)

• Health Professionals Follow-up Study (HPFS).

A total of 111,654 participants were included where they looked at association between types of chocolate (dark and milk) versus T2D.

The main reported findings were as follows:

1. “Participants who consumed ≥5 servings/week of dark chocolate [but not milk chocolate] showed a 21% lower risk of T2D.

2. Intake of milk, but not dark, chocolate was positively associated with weight gain.

Sounds nice. And if you want to believe Dark Chocolate will protect you from T2D, you should stop the video here and go enjoy ignorance is bliss…

Oh, you’re still watching. Very well, let’s discuss why I’m skeptical that Dark Chocolate will meaningfully reduce your risk of T2D.

Major Limitations & Confounders

First, there was a clear signal of healthy user bias in the study.

This means that one group (in this case dark chocolate eaters) tend to have other healthy habits that can explain the observed effect (here lower incidence of T2D).

I’ve marked able Table 1 from the study to help illustrate this point. The three cohorts are partitioned by the vertical black lines. And you can see there is a consistent and dose-dependent pattern whereby those who ate more dark chocolate exhibited:

• more physical activity (red)

• more multivitamin use (blue)

• generally higher overall diet quality score (purple)

• lower BMI (pink)

Conversely, for high milk chocolate users had suggestions of less healthy living, including higher smoking rate and lower diet quality score.

So, is it as simple as those who choose to eat dark chocolate are healthier people and those who choose to eat milk chocolate are less healthy?

Maybe.

Although, a challenge to this could be, “But they adjusted for these factors in their mathematical modeling.” However, these adjustments are just best guesses, and necessarily incomplete.

In fact, the authors themselves write, “we cannot entirely rule out the role of confounding in our observed associations… residual or unmeasured confounding, or both, may still exist.”

Furthermore, in a subgroup analysis, there also found no association between dark chocolate consumption and T2D risk among individuals with a lower quality diet (HR 0.87, 95% CI 0.68 to 1.10). This is consistent with the idea that confounders (the healthy user bias we mentioned) were carrying the lion’s share of the reported effect.

Three Cohorts Show Inconsistent Findings

Another big red flag is that there was massive heterogeneity among the studies. In other words, the associations between dark chocolate intake and T2D were not at all consistent among the three cohorts.

In fact, they were primarily driven by one of the three, with a supposed 51% reduced risk of T2D in heavy chocolate users in the HPFS, which I think it quite an absurd value, and one with a giant confidence interval at that (8% to 74%), and no association noted in the Nurses’ Health Study (NHS).

The paper reads, “In NHS, neither total nor subtypes of chocolate consumption were statistically significantly associated with risk of T2D.”

If this was a biological phenomenon based on reliable data, one would expect the data to be more consistent. Instead, the data appear as noisy as an attention-hungry elephant with a bullhorn.

What is “Dark Chocolate?”

And as a last aside before we summarize, and what’s “dark chocolate” anyway? Are we talking 95% or 100% dark chocolate bars? Or 50% “dark chocolate” truffles.

Since it’s a self-reported questionnaire, these items get lumped, although they’re obviously not the same.

Actually, in the discussion they do define dark chocolate – a somewhat arbitrary term – with a lower bound of 50% cocoa. I don’t know about you, but to me that’s candy, not true dark chocolate. Just my two cents. Then again, I’m a chocolate snob.

TLDR: Is Dark Chocolate Healthy?

Setting this study aside for a moment, if we look at the larger body of literature, I think there is definitely something to “flavanols” (put a pin in that word for a moment) in chocolates being health-promoting, perhaps more so for cardiovascular health than T2D protection.

However, these new BMJ data don’t inspire within me confidence that dark chocolate, as defined in this study in protecting against diabetes. I think the bulk of the apparent “protective” effect of dark chocolate against T2D here is more a function of other factors that happen to cluster with dark chocolate consumption.

The big point is, I really don’t put much stock in these data. I think the headlines are just that headlines.

Complicated Chocolate: Why are There Conflicting Data?

So, before this paper there were conflicting data on whether dark chocolate might protect against T2D. And now, well – I don’t think the story has changed. But we’re not done. Because now we need to ask, WHY?

Why are the data conflicted and why can’t we get a straight answer on what seems like a simple question?

Well, setting aside the fact that’s it’s next to impossible to do a proper randomized controlled trial isolating one food for incidence on chronic disease – as we mentioned – there’s huge variability in what we’re calling dark chocolate.

I think we can agree that 50% dark chocolate truffle with sugar and additives and 100% dark chocolate bar are two very different things.

But beyond that consider that there many variables that result in variation of the pure “cocoa” that goes the manufacturer, even before they start to process it and mix it with other ingredients to make your chocolate!

• There are different varieties of Theobroma Cacao plant, at least 10.

• There are grown in different regions with different soil conditions.

• They are fermented by different microbes – yes, chocolate is a fermented food.

• And fermented for different durations.

And all this happens well before the chocolate goes to the manufacturer. Then there is roasting, “conching,” and all these steps which can all change the chocolate flavor and nutrient profiles. And that’s all separate from the added sugar and % chocolate. Crazy right?!

For more on chocolate production, this is a great video:

I’m Still a Chocolate Fan. Here is what I Suggest

So, it’s easy to see how chocolate science can get confusing. But to make things as simple as possible for you – before we get to the practical tips – on balance I think dark chocolate is a perfectly healthy food.

It can be high in flavanols/anti-oxidants, fiber (if that’s a target for you… not going to attach that can of worms in this letter), and healthy fats (including the saturated fats).

And dark chocolate without much added sugar doesn’t tend to spike blood sugar given its low glycemic impact, with a glycemic index of around 20 on a roughly 0 to 100 scale, with zero being carb-free foods like eggs and 100 being pure glucose sugar.

And – honestly – the best thing you can do to reduce your risk of T2D is to eat in a way that reduces sugar intake and keeps your blood sugar stable. Chocolate can be part of this method, and I think pairs nicely with other blood sugar stabilizing healthy fatty foods like a good macadamia butter or tahini. So – on balance – I say go for it.

I’ve bee using House of Macadamia for >5 years. Absolutely love it. Discount code NICK10 on anything in store.

How to Get the Most Out of Your Chocolate

Well, the heuristic the darker the healthier still applies. Shoot for something >80% dark chocolate.

If you can find it, some makers will even put the flavanol content on the packaging.

Flavanols are the family of antioxidant compounds thought to give dark chocolate it’s health halo. The main flavanol in chocolate is epicatechin, which has been shown to have some benefits on blood flow, blood pressure, and possibly mitochondrial function and is also found in foods like green tea.

So, if you can find chocolate with a flavanol level on the package, that’s great.

If you can’t, generally less processed chocolates will boast higher flavanol levels. That means less Roasting, less alkalinization and less dutching. These are processes that reduce flavanols in chocolate.

My personal favorite chocolate – no affiliation – is Stone Ground 95% Taza. The Stone Ground processing preserves the flavanols, and it’s super delicious.

Another option is to use pure cacao or cacao powder, which you can mix in with things like that macadamia butter or tahini I mentioned.

I’ll have more to say on this matter in a Future Video. But, for now, I hope you found this enlightening. I think chocolate is great. But this study … meh.