"Does my diet have anything to do with my acne?" When I was in dermatology training 20 years ago, my professors all answered this question the same way. "The research studies that have been done have never found a link between diet and acne." It turns out we were wrong.
It's not the chocolate: it's the sugar. How the original research studies got it wrong
Researchers went back and looked at the original studies. In one of the largest studies, performed in the 1960s, researchers studied 65 individuals. Half the group was given chocolate bars, while the other half received bars without chocolate. After 4 weeks, they compared the two groups to see if there was a difference in acne.
After 4 weeks of eating different candy bars, there was no difference in acne between the two groups. Because of this study, the researchers concluded that chocolate did not have any effect on acne. The results of this study and others then permeated our recommendations for the next several decades.
What did they get wrong? Both groups were still eating candy bars. Yes, the comparison group didn't have chocolate in their candy bars. BUT they did have sugar and trans fats.
And the sugar is what you need to worry about.
Research now points to sugar as a major potential culprit in acne. Multiple studies have now found that diets with a high glycemic load can trigger acne in certain persons. Is this the case for everybody? Definitely not. Some people have a genetic tendency towards acne, and teenagers are especially susceptible because of hormonal changes However, diet may play a role in some people.
The research behind dietary change in acne: supportive evidence from randomized controlled trials
Researchers have looked again at the link between acne and diet, with high-quality medical studies. They've even performed randomized controlled trials (RCTs). This type of medical study involves an experiment, and it's considered one of the best types of evidence for proving a link between diet and health.
In one RCT looking at the effects of diet on acne, researchers looked specifically at the effect of a low glycemic load diet (known as a low GL diet). The researchers started with a group of male patients who all had acne, and then randomly assigned them to two groups.
In this study, one group was asked to follow a low glycemic load (low GL) diet. In a low GL diet, you need to think about both the quality and quantity of carbohydrates. In other words, you need to think about the type of carbs you're consuming as well as the amount of carbs.
A low GL diet focuses on foods with a lower glycemic index. The glycemic index (GI) is a measure of how much your blood sugar level rise after eating a particular food. Foods with a high GI, such as candy bars, cause sharp, sudden rises in blood sugar levels. Foods with a lower GI, such as lentils, lead to a slow, steady rise in blood sugar levels, which is ideal.
As an example of diet changes in this study, volunteers were asked to eat whole grain bread instead of white bread. They were also asked to reduce their carbohydrate intake by cutting out high GI foods and replacing them with foods that were higher in protein, such as fish and poultry.
It's important to realize that they were NOT asked to follow a low carb diet. Their recommended diet plan was designed to provide 25% of energy from protein, 45% from low GI carbs, and 30% from fat. In addition, the suggested diet was designed to provide the same number of calories as their previous diet.
The other group of volunteers served as a comparison group. They were asked to eat foods that were similar to their regular diet, with carbs that had moderate to high GI values.
Both groups followed their diet plan for 12 weeks. At the end of that time, the results were clear. The volunteers in the low GL group had a much greater improvement in their acne. They had fewer red bumps and pustules. They even had fewer whiteheads and blackheads.
Other research studies have found similar results. Testing has even shown that a low GL diet causes beneficial changes in hormone levels and skin sebum production.
In another RCT, volunteers were asked to follow a 10-week low glycemic load diet. At the end of the 10 weeks, those on the low GL diet had improvement in their skin. This study even went further and took skin biopsies. These biopsies showed a decrease in skin inflammation. The biopsies even showed that the volunteers had smaller sebaceous (oil) glands after being on the low GL diet.
Dairy may be an issue for some, but not all. And you may need to watch out for whey protein supplements
What about dairy? The evidence is less strong for milk and dairy products serving as an acne trigger, but in some individuals, they may be a trigger. Even milk that comes from cows never treated with growth hormone can be a trigger. The theory is that since milk is used to help baby cows grow, it naturally contains many hormones, and these may contribute to the development of acne.
There was also a recent report of 5 teenagers who developed moderate to severe acne after starting whey protein supplements. None had responded to acne treatment with antibiotics by mouth and topical medications. What finally cleared their skin? In 4 of these patients, their acne completely cleared after stopping the whey protein. What about foods that fight inflammation? There's been a suggestion that foods that fight inflammation may be helpful in improving acne. Foods that fight inflammation include the antioxidants in fruits and vegetables and the omega-3 fatty acids in fish. There's less evidence for this, but given all the health benefits of these anti-inflammatory foods, I recommend them. This page provides more details on the foods that may be helpful in acne.
What to avoid or limit when you have acne: translating the research into dietary change
There's strong evidence that foods that cause rapid elevations in blood sugar levels (also known as sugar spikes) may promote acne in some people. [For more information on how to avoid blood sugar spikes, see this page.]
It's worth a try to eat less sugar over the next 8 weeks. That means less soda and fewer cookies, cupcakes, and candy bars. Also be careful about less obvious sources of sugar, like your breakfast cereal and bottled iced tea.
Also cut down on other foods that can spike your blood sugar. This means less refined carbohydrates such as white bread, white pasta, and crackers. The carbohydrates in these foods are digested quickly, which translates to blood sugar spikes. Instead, focus on foods that provide power carbs. Power carbs are those that include a dose of fiber and/or protein, along with other nutrients. Power carbs include whole/intact grains, beans, and lentils.
If you're taking whey protein powder as a nutritional supplement, it's worth a try to stop for 8 weeks.
Milk and dairy products may be an acne trigger in some people, but may have no effect in others. If you're going to drink milk, I recommend organic milk and dairy products that haven't been treated with bovine growth hormone.
As you can see just by looking at skin with acne, there's a lot of inflammation involved. Will anti-inflammatory foods help? We don't know for sure, but preliminary research is promising. Most fruits and vegetables in their natural form are anti-inflammatory. They're not only high in vitamins and minerals, they are great sources of fiber and many phytonutrients (substances in plants that are being studied for their disease-fighting power).
The Bottom Line: Will these dietary changes help? There's no way to know for sure, since every case is different, but while you're taking your acne medications, it's definitely worth a try to change your diet at the same time. Also keep in mind that it may take 8-12 weeks to see improvement.
Dr. Rajani Katta is the author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. To receive future updates on preventive dermatology and the role of diet, sign up here.