Is it true that foods such as french fries, candy, chocolate, and milk cause acne? Do fat, sugar, and dairy really have adverse effects on your skin? Although many of us grew up believing that our diet was intimately tied to our complexion, the association is not clear-cut.
Our perception that certain foods can exacerbate acne is largely based on the beliefs of the mid-20th century. During this time, physicians would often incorporate dietary modifications into their patients’ treatment plans, counseling them to avoid foods high in sugar, fat, and excessive carbohydrates. Unfortunately, these recommendations were not backed by reliable and well-constructed scientific studies. Although dietary therapy fell out of favor among the medical community in the 1960s, the general public’s association between diet and acne remained. However, recent research shows that there may be some truth to these long-standing beliefs.
Some studies indicate that people in Western cultures have more acne than those in non-Western cultures. For example, one study looked at 9,955 children aged 6-16 in rural Brazil and found that only 2.7% of them had acne – a much lower percentage than what is seen in the US. Some have attributed this discrepancy to a difference in diet. Supporting that belief is the observation that acne prevalence has been shown to increase as cultures become more Westernized. For example, as the Inuit (Eskimo) population acculturated, their prevalence of acne went from almost non-existent to being equivalent to that of Western populations.
Although these observations are interesting, a definitive association between diet and acne cannot be made based on this evidence. There are obviously many differences between Western and non-Western cultures, as well as Westernized and non-Westernized cultures, of which diet is only one.
So what do studies looking at specific types of food tell us about the relationship between diet and acne? To date, the most impressive body of evidence linking diet to acne implicates high-glycemic-index foods. There is also some weaker evidence supporting the role of dairy in the development of acne.
The glycemic index describes the effect of specific carbohydrates on blood sugar levels. High-glycemic-index foods such as white bread, cereals, potatoes, cookies, chips, and white rice are digested quickly and cause a rapid increase in the amount of glucose in the blood. This sharp rise in glucose increases the amount of insulin in the body to a higher level than with low-glycemic-index foods. The high insulin affects hormones and signaling pathways within the body that may promote the development of acne. One study of 15- to 25-year-old men found that initiating a low-glycemic-index diet cleared up their acne lesions. In an online survey of 2,500 participants beginning the South Beach Diet (a low-glycemic eating plan), 86.7% reported improvements in their acne lesions. If high-glycemic-index foods do indeed promote acne, one of the reasons why non-Westernized cultures have a lower prevalence of acne may be due to their low-glycemic-index diets, as their daily intake tends to be largely composed of unrefined carbohydrates.
Some studies have linked dairy to acne, although the association is much weaker. Interestingly, one study showed that skim milk may be more comedogenic (acne-causing) than other types of milk. Milk is believed to cause acne by two mechanisms related to hormones. The first is by stimulating insulin, which sets off a pathway that increases the amount of testosterone in the body. The second is related to the hormones already present in milk. These include testosterone precursors, which are converted within the skin into a hormone that stimulates acne production.
If it is true that some foods can worsen your acne lesions, can any foods improve your complexion? Some studies have shown that omega-3 fatty acids may have anti-inflammatory properties, causing an improvement in the appearance of acne. Other studies have shown that high-fiber diets are associated with less acne. This is not surprising because diets higher in fiber also tend to be lower in glycemic index.
What about antioxidants? Antioxidants decrease the number of reactive oxygen species in circulation. Since these reactive oxygen species play a large role in inflammation, it would make sense that their reduced circulation would equate with a better complexion. Resveratrol, a popular antioxidant found in the skin of red grapes, has been shown in the laboratory to kill the bacterium specific to the development of acne, Propionibacterium acnes. In addition, a separate study found that participants with low levels of Vitamin A and Vitamin E had more severe acne than those with higher levels of these antioxidants.
These new insights into diet and acne are the result of modern studies attempting to clarify this intricate relationship. Although research in this field is increasing, there are currently no definitive answers. The strongest evidence exists for high-glycemic-index foods causing acne, with weaker evidence implicating dairy in its development. Studies investigating foods that may improve the complexion are less well-developed.
The recommended rule of thumb is to listen to your skin. If you observe that certain foods worsen your acne lesions (and many patients do!), it is a good idea to avoid those foods. Keeping a food diary is a great way to identify whether you have any dietary triggers. You should also note any possible confounding events, such as your menstrual cycle if you are female, to be certain that the suspected food is actually causing your acne. Once identified, one way to test a belief is to practice an elimination diet. What happens to your skin when you remove that food from your diet? If you choose to do this, it is important to keep in mind that foods provide important nutrients. Calcium, for example, is crucial to normal growth and bone health, especially if you are an adolescent. Therefore, if you choose to cut dairy out of your diet, you must take a calcium and Vitamin D supplement. Different supplementation may be necessary when omitting other food groups, and it is therefore always best to consult a physician when making drastic dietary alterations. It is also recommended that you do not attempt to oversupplement with vitamins and minerals, as these agents can have serious side effects when ingested in excessive amounts.
Dr. Silvina Pugliese is the creator of DermHub.