Studies have shown that newly diagnosed acne patients tend to have lower levels of vitamin A circulating in their bloodstream than those who are acne free.^[43] In addition people with severe acne also tend to have lower blood levels of vitamin E.^[44]

The long-held belief that there is no link between diets high in refined sugars and processed foods, and acne, has recently been challenged.^[26] The previous belief was based on earlier studies (some using chocolate and Coca-Cola) that were methodologically flawed.^[26][27][28] The recent low glycemic-load hypothesis postulates that rapidly digested carbohydrate foods (such as soft drinks, sweets, white bread) produce an overload in blood glucose (hyperglycemia) that stimulates the secretion of insulin, which in turn triggers the release of IGF-1.^[26] IGF-1 has direct effects on the pilosebaceous unit (and insulin at high concentrations can also bind to the IGF-1 receptor)^[29] and has been shown to stimulate hyperkeratosis and epidermal hyperplasia.^[30] These events facilitate acne formation. Sugar consumption might also influence the activity of androgens via a decrease in sex hormone-binding globulin concentration.^[31][32]