Friday Favorites: Do Chocolate and Cocoa Powder Cause Acne?

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.

Acne affects nearly one in ten people in the world, “making it [perhaps] the eighth most prevalent disease worldwide.” What’s the role of nutrition? Well, go back a century, and dermatology textbooks were recommending various dietary restrictions. For example, recommending those with acne avoid foods like “pork, sausage, cheese, pickles, pastries,…sweets, cocoa, and chocolate.”

Yeah, but old-timey medicine was full of crackpot theories. Dr. Kellogg, for example, blamed acne on masturbation. Nothing a few corn flakes couldn’t fix, though!

Population studies have found associations between acne and the consumption of foods like dairy, sweets, and chocolate. But, you don’t know if it’s cause and effect until you put it to the test. There have been high quality reports, like the Harvard Nurses study, that looked at nearly 50,000 women, and found a link between adolescent milk-drinking and acne—particularly skim milk, something that’s been found for teenage boys as well.

They thought it might be the hormones in milk that were responsible. But, it could also be the milk protein, whey—of which they add extra to skim milk to make it less watery—which may play a direct role in acne formation or as hormonal carriers. That would explain cases like this, where whey-protein powders were implicated in precipitating acne flares in teens who had acne that just didn’t seem to want to go away, until they stopped the whey. It doesn’t appear to just be a protein effect, since soy-protein supplements, for example, did not seem to cause the same problem.

But, for dairy, in terms of interventional studies, all we have are these kinds of case series. If you do a systematic review of acne and nutrition, you get results like this for dairy: out of the 20 or so papers on acne and dairy out there, about three-quarters suggest adverse effects, and the remainder report no effect, with no studies suggesting a beneficial effect of dairy on acne. So, you could look at this and conclude a dairy-free diet is worth a try. But, this is based on low-grade evidence, level C and D evidence, where C is like the population studies, and D is like those series of case reports. What we want, ideally, are randomized interventional studies—level A and B evidence, which we don’t have for dairy, but we do have for chocolate.

When it comes to acne, no food is “more universally condemned than chocolate.” So, if you’re the “Chocolate Manufacturers Association,” how are you going to design a study to make your product not look so bad? Well, you can always use the old drug company trick of pitting your product against something even worse. And so, they fed people chocolate bars, versus fake chocolate bars made out of partially hydrogenated vegetable oil: trans fats. So, make it have more sugar, throw in some milk protein, and make it 28% pure trans-fat laden, Crisco-like vegetable shortening. And, surprise, surprise, there were just as many pimples on the fake chocolate bars— allowing them to conclude that eating high amounts of chocolate is A-OK when it comes to acne.

And, the medical community fell for it. “Have we been guilty of taking candy away from babies?” “Too many patients harbor the delusion that their health can somehow be mysteriously harmed by something in their diet.” That original study “finding that chocolate consumption supposedly does not exacerbate acne has continued to remain virtually unchallenged for decades and continues to be cited even in…recent review[s].” For example, this pediatrics journal. Years ago, it was “demonstrated that chocolate consumption had no effect on acne.”

“…[T]his serves as a cautionary example of how ‘research-based evidence’ should be vigorously scrutinized prior to being incorporated into clinical practice.” Just because something is published in the Journal of the American Medical Association doesn’t necessarily mean it’s a good study— especially when industry interests are involved.

Maybe we should be telling acne patients to try cutting down on not only the sweets and the dairy, but also the trans fats found in partially hydrogenated vegetable oils. But, we can’t “be unequivocal in [our] advice to acne sufferers” on foods to include or exclude until they’re put to the test in “well-designed randomized controlled clinical trial[s].” But, there simply weren’t any such trials on acne, until, now—which we’ll cover, next.

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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