Therapeutic Update: Acne

Acne vulgaris is the most frequent primary diagnosis reported by dermatologists.¹ To some degree, it affects nearly all adolescents, presenting as comedones, papules and pustules and in severe cases nodules and cysts.² Acne pathogenesis relies on four primary factors: excess sebum production, Propionibacterium acnes (P. acnes) follicular colonization, abnormal keratinization and inflammation. While abnormal keratinization resulting in the microcomedone was classically considered the first step in the acne process, we now know that inflammation is the inciting factor, working through Toll-like receptor (TLR)- 2.³ To combat the multiple factors of acne pathogenesis, while simultaneously addressing an increasing desire for natural and alternative therapies, lifestyle interventions as well as pharmacologic therapy characterize the holistic approach most acne patients require.

The evidence supporting a link between diet and acne continues to grow, with high glycemic index diets and dairy consumption emerging as the most consistent triggers. Adolescent patients placed on a low glycemic index diet showed a significant decrease in free androgen index and acne severity.^4,5 Biopsy specimens of acne lesions performed at baseline and at ten-weeks demonstrated a decrease in the sebaceous gland size, the number of inflammatory cells and the expression of inflammatory cytokines, such as interleukin-8.⁵ Foods with high glycemic indices include white bread, white potatoes, pretzels, chips, cornflakes and white rice, while multigrain bread, beans, vegetables and proteins and seeds illustrate examples of foods with a low glycemic index. Certain dairy beverages, specifically skim milk, also appear to contribute to acne formation. Although retrospective and based on patient reporting, food consumption questionnaires showed an increased risk for acne development in those who consumed milk or ice cream.⁶ No association was seen with yogurt or cheese consumption.⁶ High glycemic index foods and dairy consumption increase androgen levels and insulin-like growth factor-1(IGF-1); IGF-1 controls signaling of the Fox01 nuclear transcription factor. ^7,8 Fox01 in combination with nutrient-sensitive kinase mTOR complex 1 signaling are currently hypothesized to be the primary mediators of food-induced acne promotion^7,8; however, more research is required to fully elucidate this mechanism.

While most dairy products seem to exacerbate acne, a notable exception appears to be yogurt. In fact, yogurt with live active cultures, or probiotics, seems to be protective when it comes to the development of acne. Probiotics seems to impact acne through what has become known as the “gut-brain-skin axis”.⁹ Psychological distress alone, or in combination with refined, processed foods, slows gut motility and alter gastrointestinal flora, leading to increased intestinal permeability. This in turn leads to systemic inflammation and decreased insulin sensitivity, and the cascade of events is thought to promote acne in predisposed individuals. Oral probiotics have been shown to normalize the gut