Acne Vulgaris: Nutritional Considerations

Some studies suggest that acne occurs more commonly in countries following Westernized diets. However, the role of nutritional factors remains unclear. For years, dermatologists advised people to avoid chocolate, fried foods, and fatty foods, although proof of their role was lacking. Acne may not be worse in individuals with a higher intake of table sugar or chocolate.

Recent evidence suggests that diet may indeed contribute to hormone–related acne. In population studies, the following factors are associated with acne:

Western diets and acne: Indigenous populations that eat plant–based diets composed mainly (roughly 70 percent) of unprocessed or minimally processed foods high in carbohydrate and fiber, and emphasizing unsaturated, rather than saturated, fats (tubers, fruit, vegetables, peanuts, corn, and rice), are largely free of acne. In contrast, the vast majority of teenagers and 40 to 54 percent of the adult population in Western societies have some degree of facial acne.

Evidence also suggests that, as immigrants begin a typical Western diet, their previously low incidence of acne rises to the levels found in Western societies. Aspects of diet under particular scrutiny are as follows:

• Dietary fat contributes to acne production, and excesses of both fat and carbohydrate contribute to increased fat secretion in human skin. In contrast, restricting calories can reduce acne production by as much as 40 percent.
  
  Diets high in saturated fat, meat, and milk increase blood concentrations of insulin–like growth factor (IGF–I), which, in turn, stimulates the production of sex hormones that increase acne production. Plant–based diets, low–fat diets, high–fiber diets, and vegetarian diets reduce levels of IGF–I.
• Dairy products may play a role in acne. In the Nurses Health Study II, more than 47,000 women completed questionnaires based on recalling their diet during high school, and associations were estimated between various food groups and diagnosis of teenage acne. Women who reported having consumed more than two glasses of skim milk per day during their teen years (ages 13 to 18) had a 40 percent greater prevalence of teenage acne, compared with those drinking less than one glass per week.

While mechanisms that might explain the association have not been established, several possibilities have been suggested. Milk contains both hormones and hormone–like chemicals (e.g., IGF–I) that may survive processing and affect the skin glands. Apart from the hormones found in milk, hormones or growth factors may be produced in the human body in response to milk ingestion. For instance, regular milk ingestion by adults is associated with an elevation of blood IGF–I concentrations.