Early studies about diet and acne focused on specific foods believed to trigger acne breakouts. Most of these studies found no evidence that individual foods cause acne.
Studies of the diets of ethnic groups that have a low incidence of acne form the basis of most of the acne diets. Studies of the diets of tribes in New Guinea, Paraguay, and the Bantu of South Africa, all of whom have little or no acne, show that they eat a primarily plant-based diet. Similarly, in other countries where the diet is plant-based such as Japan, there is a relatively low occurrence of acne.
Studies have shown that half of acne patients tested had abnormal glucose levels, and in another study, 80%of premenstrual women with acne had abnormal glucose metabolism These data and others that show a high carbohydrate diet increases the levels of testosterone in the blood of both men and women, have lead to the recommendation of reducing the amount high carbohydrate foods or foods containing high levels of refined sugar to treat acne.
Researchers have developed a method for measuring how quickly carbohydrates are converted into glucose. The more rapidly a food is converted to glucose, the higher the level of insulin is secreted into the blood. The scale is called the glycemic index. Eating lower glycemic index foods may help reduce the number and severity of acne breakouts.
A large study of over 45,000 nurses found a link between the amount of dairy products these women consumed and the severity of acne they experienced. Women who reported consuming higher amounts of dairy products reported more severe acne. Similarly, the two ethnic groups with little or no acne also consumed no dairy products.
Several studies have compared the results of zinc supplementation with oral antibiotic therapy to resolved acne and found zinc to be almost as effective as the antibiotic tetracycline.
