Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

A century ago, “diet was commonly used as [part of the] treatment for acne. During the 1960s, however, the diet-acne connection fell out of favor.” Why? Because of a study purported to “prove…that chocolate had no influence on acne, by comparing a chocolate bar to a pseudochocolate bar composed of 28% [pure trans-fat laden, partially] hydrogenated vegetable oil, a [substance] known to increase [signs of inflammation].” Compared to that, no wonder the chocolate didn’t come out looking so bad.

And then, there was this other study, where small groups of medical students ate a variety of purported culprits, and only about a third broke out. But, there was no control group to compare to. Yet, these two studies, despite their “major design flaws, were sufficient to dissociate diet from acne in the minds of most dermatologists. Textbooks were revised to reflect this new academic consensus, and dermatologists took the stance that any mumblings about the association between diet and acne were unscientific and one of the many myths surrounding this ubiquitous disease.”

Comments such as “The association of diet with acne has…been relegated to the category of myth” “are commonplace in both the past and current [medical] literature.” Yet, the major dermatology textbooks “promulgat[ing this] notion that diet and acne are unrelated…rely only on” those two flawed studies. So, this current thought “within the dermatology community that diet and acne are unrelated has little or no factual support.”

And, there’s reason to suspect chocolate consumption may be an issue. If you take blood from people before and after eating a couple bars of milk chocolate, the milk chocolate appears to prime some of their pus cells to release extra inflammatory chemicals when you expose them to acne-causing bacteria in a petri dish. So, maybe this is “one of the mechanisms that could explain the effects of chocolate on acne.” But, how do we know it’s the chocolate, and not the added sugar or milk?

Yes, if you survey teens on their acne severity and eating habits, there appears to be a link to chocolate consumption. But, is that people sprinkling cocoa powder in their smoothie, or eating dark chocolate? Or, is it because of the added sugar and milk?

Just cutting down on sugary foods and refined grains can cut pimple counts in half in a few months—significantly better than the control group, complete with compelling before-and-after pictures.

To tease out if it was the sugar, researchers gave people milk chocolate versus jelly beans. If it was just the sugar, then acne would presumably get equally worse in both groups. But, instead, the chocolate group got worse—a doubling of acne lesions, whereas no change in the jelly-bean group. So, it’s apparently not just the sugar; maybe there is something in chocolate. Or is it only in milk chocolate?

“So far, there [had] been no studies assessing the effects of pure [100%] chocolate…on acne”—that is, until there were! “57 volunteers with mild-to-moderate acne…were randomized in[to] three groups, receiving…” white chocolate bars, dark chocolate bars, or no chocolate bars every day for a month. And, this wasn’t just dark chocolate, but 100% chocolate, meaning like baker’s chocolate. Unlike pure dark chocolate, white chocolate is packed with sugar and milk. And, indeed, acne lesions worsened in the white-chocolate group, but not in the dark-chocolate or control groups. So, in “this study, white but not dark chocolate consumption [was] associated with [an] exacerbation of acne lesions.

But, other studies did show acne worsening on dark chocolate. Give research subjects a single big load of Ghirardelli baking chocolate, and they break out within days. A “[s]ignificant increase…in the total average number of acne…lesions” within four days. And, same thing with more chronic dark chocolate consumption: a half a small chocolate bar a day for a month, and increased acne severity was reported within two weeks, with before-and-after pictures looking like this.

Okay, but what was lacking in these two studies? Give people chocolate every day, and their acne gets worse, or one big load of chocolate and their acne gets worse. What didn’t these studies include? Long-time NutritionFacts followers should know this by now. Right, they’re missing a control group.

If you look at surveys, most people believe chocolate causes acne. So, if you give people a big load of chocolate, maybe just the stress and expectation that they’re going to have an outbreak contributes to the actual outbreak. To really get to the bottom of this, you’d have to design a study where you give people disguised chocolate. You expose people to chocolate without them knowing it, and see if they still break out. Like, you could put cocoa powder into opaque capsules, so they don’t know if they’re getting cocoa or placebo. And, that would have the additional benefit of eliminating the cocoa-butter fat factor. No milk, no sugar, no fat—just pure cocoa powder in capsules, versus placebo. But, there had never been such a study… until now.

“A double-blind, placebo-controlled study assessing the effect of chocolate consumption,” actually cocoa powder consumption, “in subjects with a history of acne…” They were “assigned to swallow capsules filled with either unsweetened 100-percent cocoa,” or a placebo of like an unflavored, unsweetened jello powder. Just a “one-time binge,” requiring the swallowing of up to “240 capsules” to try to secretly expose people to a few ounces of cocoa powder. And, the same significant increase, the same doubling of acne lesions within four days, like in that Ghirardelli study. So, sadly, it really does appear that in acne-prone individuals, the consumption of cocoa may cause an increase in acne.

Now, the study did just include men. So, they didn’t have to deal with cyclical hormonal changes. And, it’s hard to imagine that the real cocoa group, after swallowing hundreds of capsules, didn’t burp up some cocoa taste, and know they were not just in the placebo group. But, the best available balance of evidence does suggest that if you’re bothered by acne, you may want to try backing off on chocolate to see if your symptoms improve.

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