Diet and Acne Update: Carbohydrates Emerge as the Main Culprit

Acne vulgaris is a common skin condition, particularly in developed Western nations. More than 85% of adolescents suffer from this ubiquitous and psychologically debilitating disease, which is moderate to severe in about 15–20% of patients.¹ Acne often persists into adulthood with 64% of individuals in their 20s and 43% of individuals in their 30s showing signs of visible acne.^2,3,4 Another study of more than 2000 adults showed that 3% of men and 5% of women still had definite mild acne at the age of 40 to 49 years.⁵

Pathogenesis of acne is characterized by androgen-stimulated overproduction of sebum, follicular hyperkeratinization, inflammatory mediators, and colonization by organisms such as Propionibacterium acnes.⁶ These generally agreed on factors have guided treatment towards hormone control, antimicrobial therapy, and vitamin A derivatives. We are well aware that genetics can strongly influence a patient’s risk of developing acne. However, with the prevalence of adult acne in the US increasing over the last few decades⁷, significant changes in germline genetic variants are unlikely. Consequently, elucidating the relationship of environmental factors such as nutrition and diet have become more important in the recent study of acne.

The relationship between diet and acne, however, has been historically controversial. In the1930s through the 1960s, patients were regularly counseled regarding their dietary habits, as dietary triggers were thought to play a major role in acne. Following two critically impactful studies^8,9 dietary restrictions were deemed no longer necessary. The idea that diet affected acne was relegated to myth. In 2007, one of the authors¹⁰ published a review in the JAAD re-implicating certain dietary factors in acne based on emerging evidence. This article concluded that refined carbohydrates and certain dairy products, in particular skim milk, appeared to be associated with acne.Since that review, several studies have been conducted, further elucidating which dietary factors play the largest role when it comes to acne. In this update, we present those studies and confirm our initial suspicion that refined carbohydrates are indeed the main dietary contributors to acne. This article is meant to serve as a follow up to that original JAAD publication, providing an update on the evidence linking diet and acne with a specific focus on carbohydrate intake.

PubMed - Medline database was used to allow for a thorough literature search. An attempt was made to also include published abstracts in order to broaden the search for available information. Articles published over a 4-year period (2009-2013) that reported results relating to diet and acne were incorporated. Medical Subject Headings (MESH) were used to search articles and free text to search article abstracts that contained (1) a term related to acne and (2) a term related to diet and nutrition. Prospective controlled trials, prospective and retrospective cohort studies, case-control studies, and large case series examining the role of diet in acne, published in the English language and on humans were included in this review. See Table 1.

The glycemic index (GI) is a measure of the relative potential of food to raise blood glucose levels as compared to equal amounts of carbohydrates within the food. It gives a sense of the quality of the carbohydrates present in food as it reflects the rate of carbohydrate absorption. Glycemic load (GL) determines the potential of a food to raise blood glucose as well as insulin as it accounts for the glycemic index of a particular food (quality) as well as the amount of food consumed (quantity).¹¹