What are the effects of dairy products, sugar, and chocolate on the formation of pimples?
Acne affects nearly one in ten people globally, “making it the eighth most prevalent disease worldwide.” What is nutrition’s role? If we go back a century, dermatology textbooks “recommended dietary restriction”—for example, advising those with acne to avoid foods like “pork, sausage, cheese, pickles, pastries, large amounts of sweets, cocoa, and chocolate”—but old-timey medicine was full of crackpot theories. Dr. Kellogg, for example, blamed acne on masturbation. (Nothing a few cornflakes couldn’t fix, though!)
Population studies have found associations between acne and the consumption of foods like dairy, sweets, and chocolate. You don’t know if it’s cause and effect, however, until you put it to the test—which they did, as I discuss in my video Does Chocolate Cause Acne?.
There have been high quality reports, like the Harvard Nurses’ Health Study, which looked at nearly 50,000 women, that found a link between acne and the intake of milk, particularly skim milk, during adolescence. This association has been found for teenage boys, as well. Researchers thought the hormones in milk might be responsible, but speculated it could also be the milk protein whey, which is added to skim milk to make it less watery and “might, therefore, play a role” in acne formation or as hormonal carriers. At 1:30 in my video, I discuss a case where whey protein powders were implicated in precipitating acne flares in teens who “had poor response to acne treatment regimens of oral antibiotics, topical retinoids, and benzoyl peroxide.” Their acne just didn’t seem to want to go away—until they stopped the whey supplementation. Could it just be a protein effect, though? It doesn’t seem so since soy protein supplements, for example, did not seem to cause the same problem.
For dairy, in terms of interventional studies, we only have case series, such as the one published in an article titled “Acne and Whey Protein Supplementation Among Bodybuilders.” What happens if you do a systematic review of acne and nutrition? As you can see at 2:02 in my video, out of the 20 or so papers out there on acne and dairy, about three-quarters suggest adverse effects, the remainder report no effect, and no studies suggest a beneficial effect of dairy on acne. You could look at this and conclude a dairy-free diet is worth a try, but this is based on low-grade evidence—that is, Level C and D evidence where Level C is like population studies and Level D is like those series of case reports. What we ideally want are randomized interventional studies, Level A and B evidence. We don’t have them for dairy, but we do have them for chocolate.
When it comes to acne, no food “is more universally condemned than chocolate.” If you’re the Chocolate Manufacturers Association, which “made possible” the trial we’re discussing, how are you going to design a study to make your product not look so bad? Well, you can always use the drug companies’ old trick of pitting your product against something even worse, which is just what they did. As you can see at 3:01 in my video, researchers fed people chocolate bars versus fake chocolate bars made out of partially hydrogenated vegetable oil—that is, trans fats. The fake chocolate had more sugar and included milk protein, and was 28 percent trans-fat-laden, Crisco-like vegetable shortening. Not surprisingly, subjects got just as many pimples on the fake chocolate bars as the real ones, which allowed the researchers to conclude that eating high amounts of chocolate is a-okay when it comes to acne.
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.” The original study’s “finding that chocolate consumption does not exacerbate acne has continued to remain virtually unchallenged for decades and continues to be cited even in…recent review[s].” For example, an article in Pediatric Annals, a pediatrics journal, stated that “years ago [it was] demonstrated that chocolate consumption had no effect on acne…This 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 not only on the sweets and the dairy, but also the trans fats found in partially hydrogenated vegetable oils. However, we “cannot be unequivocal in [our] advice to acne sufferers” on foods to include or exclude until they’re put to the test in “a well-designed randomized controlled clinical trial.” There simply weren’t any such trials on acne…until now. Stay tuned for my discussion of that in Does Cocoa Powder Cause Acne?.
- Acne, the eighth most prevalent disease globally, affects nearly one in ten people.
- A century ago, acne patients were encouraged to avoid foods like pork, cheese, pastries, and chocolate, and more recent population studies have found acne to be associated with intake of dairy and sweets.
- The Harvard Nurses’ Health Study found a link between acne and milk consumption, particularly skim milk, during adolescence, an association that has also been found for teen boys.
- Whey protein powders have been implicated in precipitating acne flares in teens who didn’t respond well to various acne treatment protocols, including oral antibiotics and topical retinoids. However, their acne went away after they stopped whey supplementation, and it was not a protein effect since soy protein supplements didn’t seem to cause the same problem.
- About three out of four case studies on acne and dairy suggest adverse effects, but the evidence isn’t as strong as it would be from randomized interventional studies.
- Though there aren’t any randomized interventional studies on dairy and acne, there are for chocolate, thought to be the most universally condemned food when it comes to acne.
- In a Chocolate Manufacturers Association’s study, researchers designed a misleading trial and gave subjects chocolate bars versus fake ones that were higher in sugar, contained milk protein, and was 28 percent trans-fat-laden with Crisco-like vegetable shortening. Since subjects got as many pimples on the fake chocolate bars as the real ones, researchers concluded that chocolate consumption does not exacerbate acne. Unfortunately, the medical community bought it.
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Michael Greger, M.D.
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