On the origins of acne
Acne vulgaris is a chronic inflammatory skin condition that primarily affects adolescents and young adults. It has a prevalence of 80% in individuals aged between 11 and 30, therefore affecting approximately 9% of the world population. The complex etiology of acne involves genetic, hormonal and environmental factors. Acne presents with inflammatory and non-inflammatory lesions, such as papules, pustules and comedones, with various clinical forms classified according to the severity of the lesion. Microcalcifications are involved in the formation of lesions due to hormonal disorders, sebum secretion, proliferation of Cutibacterium acnes and keratinization abnormalities. Severe acne can lead to scarring and hyperpigmentation, having a significant impact on the well-being and quality of life of those affected. The influences of diet on the development of acne are currently being studied, along with new therapeutic approaches to relieve symptoms and improve patient outcomes.
The role of nutrition
A higher prevalence of acne has been observed in Western populations compared to non-Western populations due to differences in diet. Western diets, which are primarily characterized by increased consumption of refined carbohydrates, dairy, chocolate, and saturated fats, have low levels of omega-3 fatty acids and can exacerbate acne by promoting inflammation and altering metabolic signals. More specifically, saturated fatty acids present in the Western diet induce inflammation through the expression of Toll-like receptor 2 (TLR2)/interleukin 1B (IL-1 beta), thus leading to increased secretion of IL-17A and to hyperproliferation of keratinocytes. Diets with a high glycemic index and high consumption of dairy products, such as IGF-1 and insulin, are also associated with elevated levels of hormones involved in the pathogenesis of acne.
Foods with potential adverse effect
Milk and dairy products, particularly those rich in whey protein and casein, have been associated with increased levels of IGF-1, which can lead to hyperinsulinemia and exacerbation of acne lesions. Cow’s milk also contains hormone precursors that can be converted into dihydrotestosterone (DHT), a potent acne inducer. Although there is conflicting data regarding the fat content of milk and its role in acne, it is suggested that hormones and certain bioactive molecules present in milk contribute more significantly. Consumption of chocolate, especially dark chocolate, has been associated with worsening acne symptoms. The presence of saccharides in processed chocolate can induce insulin secretion and trigger signaling pathways that promote acne lesions.
Hyperinsulinemia, which results from high glycemic index diets, stimulates IGF-1 synthesis in the liver and subsequently promotes sebaceous cell proliferation and lipogenesis. Insulin and IGF-1 lead to activation of mammalian target of rapamycin complex 1 (mTORC1), which promotes sebaceous gland enlargement, lipid synthesis, and keratinocyte proliferation, contributing to the development of acne. Abnormalities in the gut microbiome, induced by an abnormal diet, further exacerbate acne pathogenesis through dysregulation of the mTOR pathway and increased intestinal barrier permeability. Overall, diet plays a significant role in the pathogenesis of acne by influencing hormone levels, inflammation, and the composition of gut microbiota.
Saturated and trans fatty acids from animal fats and hydrogenated vegetable fats have also been implicated in the pathogenesis of acne. These fats can stimulate the production of pro-inflammatory cytokines and activate signaling pathways such as mTORC1, thus leading to increased sebum production and inflammation of the dermis. Other dietary factors such as alcohol intake, excessive salt consumption, and high-glycemic index foods such as salty snacks, eggs, sodas, corn, candy, and high-gluten diets have also been associated with acne exacerbation. This eating style is known to subvert the intestinal microbiota; indeed, there is evidence that an effective clinical improvement would be visible with cycles of probiotics (commercial lactic ferments).
The social implications
If you are wondering why if among a thousand children or adolescents with a Western diet predisposing to acne, only seven hundred develop the condition, this is the result of the ineliminable genetic terrain and the biological composition that characterizes each of us. Above all, this scientific editorial team is keen to underline the most incisive aspect of this condition: stigmatisation. Nutrition education must start from a very young age and considering how the social stigmatization of the problem has very serious effects on the current and future mental health of those affected by it, it would be ideal for family environments and institutions to collaborate for maximum awareness and prevention active.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
Scientific references
Ryguła I, Pikiewicz W et al. Nutrients 2024; 16(10):1476.
Zujko-Kowalska K et al. Nutrients. 2024 Apr; 16(9):1270.
Dabash D, Salahat H et al. Sci Rep. 2024; 14(1):4351.
Guertler A, Volsky A et al. Nutrients. 2023; 15(20):4405.