Probiotics and acne.

Acne is an inflammatory skin disease that can have serious repercussions on the quality of life of those affected. It manifests as the appearance of pimples on the face, chest, and/or upper back. Acne affects approximately 80% of teenagers and nearly 40% of adults. It is primarily due to the obstruction of skin pores due to an excess of sebum or slowed cellular renewal. A hormonal component also plays a role in the pathogenesis of acne, as well as an imbalance in the intestinal and/or skin microbiota.

• What is the connection between skin microbiota and acne?

  The bacterium Cutibacterium acnes is a key player in the development of acne. Predominantly present in sebum-rich areas, this microorganism plays a crucial role in maintaining skin pH by releasing fatty acids and inhibiting the multiplication of other bacteria. Studies have revealed that only certain strains of C. acnes are associated with the release of pro-inflammatory cytokines, while others do not contribute to the development of acne.

  In addition to C. acnes, other skin microorganisms such as C. granulosum and Malassezia can contribute to the progression of acne by promoting hyperkeratinisation of hair follicles. Indeed, these agents also hydrolyse the triglycerides in sebum and release fatty acids, which heightens inflammation and leads to the formation of comedones.

• What is the connection between gut microbiota and acne?

  The gut microbiota also plays a significant role in the formation of acne lesions. The skin and intestines are densely innervated and mutually influence each other. The bacteria present in the gut produce various types of short-chain fatty acids that impact the skin's microorganisms. For instance, we can mention Propionibacterium, an intestinal bacterium that synthesises acetate and propionate, compounds that have a antimicrobial effect against certain skin pathogens.

  An unbalanced diet high in sugar can disrupt eubiosis and promote the onset ofacne. The bacteria Lactobacillus and Bifidobacterium are particularly sensitive to these effects and may respond by releasing inflammatory compounds that will modulate the skin's resistance to skin infections.

Many studies have focused on the effects of probiotics on acne and have highlighted a real interest in these treatments. In addition to reducing skin inflammation, oral intake of probiotics helps to avoid the side effects common to traditional acne treatments (skin dryness, redness, irritation...). Here are a few examples of studies where the intake of probiotics has proven effective in improving acne:

• The first study to investigate the effects of orally administered probiotics on acne was conducted by TULLI. Carried out with 40 acne patients, it highlighted the benefits of probiotics L. acidophilus and B. bifidum. 250 mg of these freeze-dried probiotics were added to the daily antibiotic treatment of 20 patients, while the other 20 only received the antibiotic. Better clinical outcomes and a more effective reduction of acne were observed in patients supplemented with probiotics.

• Another study conducted by KABANOVA focused on the gut microflora of 114 patients suffering from papulopustular and nodulocystic acne. This revealed a disturbance in the intestinal microbiota in 54% of these patients. The addition of probiotics to these individuals' diets, alongside a standard antibiotic treatment, helped to reduce the duration of the treatment and neutralise the dysbiosis.

• We can also reference the double-blind study conducted by CHO involving 36 patients aged between 18 and 30 years old, who were suffering from acne. Over a period of 12 weeks, these individuals consumed daily fermented milk containing 200 mg of lactoferrin along with probiotics derived from Lactobacillus bulgaricus and Streptococcus thermophilus. At the end of the study, the patients experienced a significant reduction (of 38.6%) in the number of their inflammatory lesions. Furthermore, the quantity of sebum and free fatty acids significantly decreased.

The probiotics incorporated into cosmetic care are also relevant anti-acne agents. In addition to maintaining the balance of the skin microbiota, they protect the skin by strengthening the epidermal barrier and fighting against pathogens. Topical probiotics have also proven their worth in terms of inhibiting the synthesis of interleukins, pro-inflammatory cytokines playing a key role in the pathogenesis of acne. There are still many examples of the benefits of topical application of probiotics on acne in the scientific literature.

• KANG and his team have particularly focused on the effect of the bacteria Enterococcus faecalis on acne, a species of the genus Lactobacillus that acts against Cutibacterium acnes. 70 patients suffering from mild to moderate acne participated in the study and were divided into two groups. For eight weeks, individuals in the first group applied a lotion containing E. faecalis twice a day, while the others applied a placebo. At the end of the study, the scientists noted a decrease in the production of inflammatory mediators by C. acnes in the first group, as well as a significant reduction in the number and intensity of inflammatory lesions.

• A clinical trial conducted by MUIZZUDDIN has demonstrated the benefits of an aqueous lotion containing 5% of Lactobacillus plantarum. 10 volunteers suffering from mild acne and erythema applied this formulation once a day for a week. A decrease in the population density of C. acnes as well as a reduction in acne lesions was observed.

Key Takeaway : Probiotics, whether taken orally or applied topically, provide genuine help in cases of acne.

• TULLI A & al. Efficacy of regulators of the intestinal bacterial flora in the therapy of acne vulgaris. Clinical Therapeutics. (1987).

• KANG S. & al. New perspectives on acne management: An update from the Global Alliance to Enhance Acne Outcomes. Journal of the American Academy of Dermatology (2009).

• KABANOVA I. & al. Impact of the impaired intestinal microflora on the course of acne vulgaris. Clinical Medicine (2001).

• CHO Y. & al. The impact of lactoferrin-enriched fermented milk on skin surface lipids and the clinical amelioration of acne vulgaris. Nutrition (2010).

• MUIZZUDDIN N. & al. Physiological impact of a probiotic on skin. Journal of Cosmetic Science (2012).

• SUYENAGA E. & al. An exploration into the potential application of probiotics in the treatment of skin conditions: acne and atopic dermatitis. International Journal of Dermatology (2018).

• MOHAMADI M. & al. The potential of probiotics for treating acne vulgaris: A review of literature on acne and microbiota. Dermatologic therapy (2020).

• NOWICKA D. & al. Microbiome and Probiotics in Acne Vulgaris—A Narrative Review. Life (2022).