For the past 30 years, doctors, facialists and high school health-ed teachers alike have assured us up and down that, contrary to what our grandmothers may have believed, junk food does not cause acne. Snickers bars, soda and ice cream, they told us, might be unhealthy—but at least they didn’t affect our complexions. According to the American Academy of Dermatology, the belief that chocolate caused zits was an old wives’ tale, somewhere along the lines of “shaving your legs makes the hair grow back faster.”
As it turns out, those old wives may have been right all along. This past July, a study published in the American Journal of Clinical Nutrition showed a measurable link between high-glycemic diets and acne. The study followed two groups of acne-plagued males ages 15 to 25 who were told they were participating in a study on carbohydrates and protein. The first group continued to eat their usual diet, which included plenty of sugar and processed grains—foods that have a high glycemic index. The other was given whole grains, lean meat and fish, fruits and vegetables—foods with a low glycemic index. After 12 weeks, a team of dermatologists determined that the subjects in the latter group had 51 percent fewer pimples than when they started.
“It all comes down to insulin,” says Neil Mann, a professor of human nutrition at RMIT University in Melbourne, Australia, and the study’s lead researcher. Foods with a high glycemic index cause blood sugar to rise, forcing the body to bring it down with a surge of insulin. And insulin can lead to acne, both by accelerating cell growth in the pores and stimulating oil-producing hormones called androgens. This radical shift in thinking about acne challenges a stance that dates back to 1969. That was the year that three researchers published a study in the influential Journal of the American Medical Association that seemed to show that chocolate does not cause acne. Two years later, another well-known study argued that peanuts, milk and cola were also blameless. Whereas previously, medical textbooks had recommended whole-grain bread and avoidance of ice cream in the treatment of pimples, a new generation of doctors were taught that there was no connection between diet and acne.
“Those two studies, on which all our dogma on diet and acne is based, are basically full of flaws,” says Valori Treloar, a dermatologist and certified nutrition specialist in Newton, Massachusetts, who wrote a recent book on food, lifestyle and acne called The Clear Skin Diet (Cumberland House Publishing). “Frankly, I don’t think either would be published today because the standards were not rigorous enough.” Both studies, she says, were too small in subject numbers and too short in duration. More important, neither controlled any other aspect of the diet, so the researchers had no idea what else the subjects were eating.
In her book Treloar and her coauthor, naturopath Alan C. Logan, recommend a diet rich in antioxidants and omega-3 fatty acids, which have anti-inflammatory properties that appear to protect against acne.
Dairy is also under new scrutiny. In 2005 researchers from the Harvard School of Public Health published a study in the Journal of the American Academy of Dermatology that showed an association between consumption of dairy products and acne. Using data from more than 47,000 women followed in the Harvard-administered Nurses’ Health Study II, researchers found that those who consumed more than three servings of milk per day were 22 percent more likely to have suffered from acne as teens. With skim milk, the numbers were even more pronounced: Those who drank two or more glasses per day were 44 percent more likely to have experienced acne bad enough to warrant a trip to the doctor.
F. William Danby, an assistant professor of dermatology at Dartmouth Medical School and one of the authors of the study, cautions that while the data show a link between dairy and acne, they don’t definitively prove that milk gives people pimples. “It’s going to require a few more years of research,” says Danby, “but there are good scientific reasons to believe that it is actually cause and effect.” Milk and dairy products, he explains, might trigger breakouts in a number of ways, most notably because they contain the same hormones that can lead to acne in humans. Even organic milk contains these natural hormones.
Danby says he has been successfully treating his own patients through a combination of medication and a zero-dairy diet for more than 20 years. One milk-loving patient, he recalls, couldn’t understand why she suffered from breakouts when her milk-hating identical twin sister did not. Another patient endured four courses of Accutane without success, only to see her acne improve after nixing a 16-ounce-a-week Cheez Whiz habit.
“I always felt that diet played a role in acne, but there were no believable studies to back this up until recently,” says Leslie Baumann, a professor of dermatology at the University of Miami who has been advising her acne-plagued patients to limit sugar and dairy for two years now.
Researchers hypothesize that our increasing consumption of sugar, processed grains and dairy products may be behind a worldwide rise in acne incidence in both teens and adults. In fact, both Danby and Mann cite the same 2002 paper in the Archives of Dermatology, which showed that among indigenous cultures in Paraguay and Papua New Guinea who ate their ancestral diets and consumed almost no processed foods or dairy products, acne was virtually unheard of. And previous studies had shown that when people from similar cultures adopted a Western diet, they developed acne.
“We didn’t evolve to eat the foods we eat now,” explains Mann. “Dairy came along probably about 7,000 years ago. Agricultural grains were about 10,000 years ago. That’s like yesterday in evolutionary terms.”
Though literature from the American Academy of Dermatology still says that nothing you eat can cause acne, Wilma Bergfeld, a professor of dermatology at the Cleveland Clinic in Ohio, who is also one of the academy’s spokespeople, says that may soon change. Though she believes more research is needed to support the dairy hypothesis, Bergfeld calls Mann’s high-glycemic load study “exciting.”
“When you chase a pimple, you want to dry it up to make it go away, but you’re not solving the problem of why it exists. This suggests that you can get at the problem by diet,” says Bergfeld. Still, not everyone is convinced that diet and acne are so directly related. “Skin reflects general health, so I tell all of my patients to eat a balanced diet, but you don’t need to avoid specific foods,” says Joshua M. Wieder, a dermatologist in private practice and an associate clinical professor at UCLA. Wieder says he might tell his patients about Mann’s and Danby’s studies, but more data is needed before he’ll go any further than that. “These are small studies which need to be substantiated by looking at larger populations across genetic groups,” he says. To date there has been surprisingly little research on the connection between diet and acne. “Nutritional studies are notoriously difficult to run,” explains Treloar. “You need to have a large enough sample group, and you need to control what people are eating.” Mounting studies is also challenging, she adds, in an age when pharmaceutical companies are the major force behind new research. “It’s hard to get funding, because it’s hard to come up with a product that somebody’s going to make money on.”
But there is one bright spot on the horizon. That 1969 study focusing on chocolate may not have used the proper methods, but the scientists did get one thing (sort of) right, says Treloar. Pure cocoa powder and dark chocolate, if it’s at least 70 percent cocoa and doesn’t contain too much sugar, may actually alleviate acne. Cocoa contains antioxidant chemicals called flavonoids that have slight anti-inflammatory effects and improve blood flow to skin cells. Bittersweet chocolate never tasted so good.