Over the last number of years, we have been subjected to a torrent of reports about dietary supplements and they weren’t all good. Vitamin E and selenium for prostate cancer? Forget it –at best it is useless, at worst it actually increases the odds of getting the disease (this applies only to you, guys). Multivitamins to enhance your health and extend your longevity? No way; at best it does nothing for you, except blow a hole in your budget.


Unlike prescription drugs, supplements are not subject to regulation

In 2016, Frontline conducted an investigation of the supplement industry, focusing on a U.S. multivitamin manufacturer that was the subject of many complaints of severe side effects by users of their product. Here is what Stephen Ostroff MD, Acting Commissioner of the FDA had to say:

“The FDA does not do any review of dietary supplements before they come onto the market, and I think that all consumers need to understand this.”

He went on to say,

“No testing, no obligation to provide any evidence a product is effective, or even safe.  The one thing manufacturers do have to show is that they follow good manufacturing practices.” 

In other words, the product can be ineffective and unsafe, but ok to go to market if they followed the rules of good manufacturing. What??

Wait, there’s more,

“We actually don’t know the total number of manufacturers that we need to be able to inspect because there is no formal registration system that is required of manufacturers that make dietary supplements, and so we do inspections of the ones that we know about.”

Buyer beware? Don’t we need some basic information so that we can ‘beware’? So what are supplement fans supposed to do?  Well, you could start popping some chocolate? It turns out there is evidence that it could be the mother of all supplements. And, it tastes good too!


The evidence of chocolate’s health benefits

Rumors of chocolate being an elixir of health and passion (of the libidinous kind) date back to the introduction of cocoa into Europe by the Spanish conquistadores. But that’s history (defined as anything that occurred before we were born), so let’s focus on the here and now.

Dark chocolate has been shown to improve endothelial function among healthy volunteers, elderly individuals, postmenopausal women, hypertensive patients, and overweight patients (BMI 25-35 kg/m²). What does “endothelial function” translate to in clinical terms? Our blood vessels are “engineered” to dilate when blood flows through them. As you can guess, this is how blood pressure is kept low. If the vessel did not dilate – the pressure on the vessel wall would increase (this is what “high systolic pressure” means).

In a study of overweight patients, flow-mediated dilation increased by an average of 2.4% in patients who drank 11 grams of cocoa powder mixed in eight ounces of water. Interestingly, if sugar was added to the cocoa, dilation dropped to an average of 1.5%. The placebo group had a 0.8% constriction of their blood vessels.

This may sound like a piddling increase in blood flow, but it isn’t; in heart failure, it can make a clinically significant difference. Without getting into the physics of hydraulic flow, here are some actual real-life effects of such an increase.

At the Heart Failure Congress in Berlin in 2010, Andreas Flammel of University Hospital in Zurich, Switzerland reported on a small study in which he randomized 20 heart failure patients to 40 or 80 grams of flavonol-rich chocolate bars, or cocoa-free, flavonol-free placebo bars that looked and tasted like the real thing. After 4 weeks of daily chocolate intake, the 40-gram chocolate bar eaters increased their flow-mediated dilation between 4.98% and 5.98%. Among patients who consumed 80 grams of chocolate a day for 4 weeks, the flow-mediated vasodilation increased up to 6.86%.

A few caveats are in order. The study is small, and therefore the statistics are not as meaningful. Second, 40 or 80 grams a day of chocolate could add up to a hefty weight gain which is the last thing that heart failure patients need. Surprisingly, however, there was no weight gain among the chocolate-eating patients. The investigator explained that “they weren’t hungry after eating the chocolate” which is probably due to Swiss exceptionalism; I have my doubts whether American exceptionalism would work its magic in this case.

What is the major risk of elevated blood pressure? Stroke, of course. So it would make sense to look into the benefit of chocolate in stroke prevention. A study conducted in Sweden by the Karolinska Institute examined food-frequency questionnaire responses from 33,372 (ages 49-83) of women in the population-based Swedish Mammography Cohort. The results, published in the Journal of the American College of Cardiology are striking:

There was a non-significant 4% higher risk of stroke for the group averaging less than 8.9 grams of chocolate per week (1.3 grams/day). Women who consumed 8.9 to 14 grams of chocolate per week (up to 2 grams/day) had a 6% lower risk of stroke, although the difference was non-significant. But the group consuming 45 grams per week (5 grams/day) had a 20% lower risk of stroke, and that was statistically significant.


How does it work?

What is suspected to be the active ingredient in the protective effect of chocolate is a group of chemicals called flavonols. They have antioxidant activity and increase the elasticity of blood vessels.

There is a difference between the various types of chocolate in terms of their flavonol content. Dark chocolate is richest in these compounds because the extensive processing involved in making milk chocolate destroys much of the flavonols.

Bearing in mind that in the Swedish study most of the women reported eating milk chocolate, it would be interesting if there were studies that looked into dark vs. milk chocolate effects on the risk of strokes. Indeed, in a paper published in the European Heart Journal in March 2010, researchers followed 19,357 patients on the European Prospective Investigation into Cancer (EPIC) that lasted from 1994 to 2006, who were between the ages of 35 and 65. A subset of 1,568 patients recorded the kind of chocolate intake over a 24-hour period; 57% ate milk chocolate, 24% ate dark chocolate, and 2% ate white chocolate. This and a meta-analysis of several studies published in the Journal of Nutrition in March 2010 confirm that the higher the flavonol content the higher the protective effect in stroke risk.


Bottom line?

Each of these studies had some shortcomings (small numbers, questionnaire-based), but the cumulative evidence is becoming quite compelling. The different studies use different amounts and different kinds of chocolate, but the evidence is that 5-7.5 grams a day is optimal, and dark chocolate is preferable to milk chocolate. A Hershey kiss is 7.5 grams. A small chocolate square weighs 5 grams.

Personally, I have been taking one piece (5 grams) of dark chocolate (70% or 82% cocoa content) with my morning two-cup coffee fix. Trying to make this small piece last for two cups I learned to nibble on it and savor the flavor with every little bite. This is called mindful eating and if we learned to do it with all our foods we’d enjoy them more, and be healthier for it, to boot.

One additional note: if you are having trouble kicking the supplements habit, why not get chocolate-coated ones? Is there a business opportunity here?

Originally published on Oct. 20, 2011, this article has been reviewed and updated by the author.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


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