Since 1969, scientists have been investigating a possible link between chocolate and acne. Does blemish-free skin really require a chocolate-free diet?

Acne is the most common skin disease worldwide, affecting more than 85% of teenagers [1]. Acne can also affect adults, where two types of populations can be distinguished: people who developed acne during adolescence and might have persistent acne and those who develop it during adulthood, with a prevalence of women over men [2]. Although the manifestations of acne appear mainly on the skin, its effects can go much deeper, representing an emotional burden with a psychological impact on the patients. Indeed, acne represents a source of low self-esteem and embarrassment for many young adults, leading to anxiety, fear, anger and depression [3]. This is further exacerbated by misinformation and myths about acne onset and how it should be treated.

The aim of this article is to shed light on the causes of acne outbreaks and to dispel popular misconceptions about the disease. We will also discuss some scientific studies investigating the correlation between acne and diet.

Acne manifests itself mainly through the formation of pimples on the skin: our skin has pores and underlying glands which produce an oily substance called sebum. Sebum usually travels through follicles to reach the surface of the skin. However, when an excess of sebum is produced, the follicles can become plugged, resulting in a pimple. These plugs can get infected by Propionibacterium acnes, a bacterium that contributes to pimple infections [4]. Several factors can influence acne outbreak and its severity: genetics [5], stress [6], hormones [7], smoking [8], or excessive sweating. Hormonal changes occurring during adolescence and the menstrual cycle have an impact on sebum production by skin glands, and can therefore affect acne outbreaks [9]. Cosmetics and makeup were also shown to play a role in skin pore clogging [10]. Clinicians have also long suspected that diet plays a role in the development of this condition.

A recent study was conducted on  24’000 people reporting having acne at the time of the study, having had acne in the past, or with no history of acne [11]. The results showed a significant correlation between acne and the consumption of fatty and sugary products, sugar-sweetened beverages and milk, while no association was found with the consumption of meat, vegetables, fruit or dark chocolate. A plausible explanation would be that high-glycemic index foods can raise insulin blood levels which, as a result, would stimulate hormones that can increase sebum production and contribute to acne. In another study conducted on 47’000 female nurses, scientists found a positive correlation with some dairy foods (e.g. cream cheese, instant breakfast drink and cottage cheese), while no significant association was reported for French fries, chocolate candy,  or pizza [12]. The association observed with some dairy products might be related to milk content, which is known to contain hormones that also increase sebum production. Accordingly, another study conducted on 65 participants showed no association between the consumption of chocolate bars with no milk component and acne [13]. The perceived correlation with commercial chocolate products may, therefore, be confounded by the presence of milk.