Probiotics in the gut-skin axis – the case of kefir

The intestinal microbiota is linked to important functions in the host. Alterations in its composition and/or its by-products, causing loss of homeostasis, contribute to dysfunctions in other organic systems, including the skin, hence suggesting a gut-skin relationship. The oral administration of probiotics, widely associated with improved intestinal health, can act through an immunomodulatory response, both locally and systemically, presenting itself as potentially beneficial in inflammatory skin diseases such as atopic dermatitis. Traditional kefir, consumed for centuries as a health-promoting natural food, has its biological activity attributed both to the presence of a complex microbiota and to the action of the metabolites released during fermentation. The biological activity of kefir has been demonstrated in part by its ability to positively impact the intestinal microbiota, mainly based on animal models and in vitro, thus providing limited information. The nutritional and microbiological value of kefir makes its application as a probiotic in the gut-skin relationship a topic of of significant interest. This review aimed to explore the impact of probiotics as regulators of the gut-skin axis, focusing on the current knowledge of kefir as a health-promoting food. Keywords: kefir, probiotic, gut-skin axis, skin health, atopic dermatitis