Probiotics for skin health

Ponente: Kimmo Makinen, PhD

Probiotics are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host. Since their conception in the early 20th century, the health benefit applications of probiotics have been expanding, and now, a diverse range of products and strains are available for a number of consumer benefits.

The most investigated health benefits are gut comfort and protection against infections, but recent evidence also shows the efficacy of probiotics in skin health. The health benefits of probiotics are strains specific, with a single strain bringing about only limited number of specific health benefits. 

The development of a probiotic strain begins with selection of safe and well-characterized candidate strains from a microbial culture collection.  The strains are typically selected to be resistant against gastric acidity and bile salts, to have an ability to counteract potentially pathogenic bacteria, and to modulate the function of the cells of the immune system. Such trials led to the identification of the probiotic L. johnsonii La1.  

L. johnsonii La1 has been shown in human intervention trials to positively influence microbiota balance by reducing the level of the potential pathogen C. perfiringes, and to stimulate the function of the immune system as evidenced by higher activity of peripheral blood phagocytic cells. Its function in skin immunity has also been investigated. 

UV-irradiation reduces the number and function of the skin’s immune surveillance cells, Langerhans cells, which recover within 10 days after the end of exposure. In a clinical trial in which healthy volunteers received L. johnsonii La1 or placebo for 2 months, it was shown that the recovery of Langerhans cell function following UV-exposure was accelerated in the probiotic group relative to the placebo group.  This recovery was associated with a faster influx into the epidermis of Langerhans cell precursor cells, lower recruitment of monocytic cells, and a potentially anti-inflammatory shift in the levels of epidermal  interleukin-6, interleukin-8, TNF-α, and interleukin-10. Therefore, L. johnsonii La1 may be considered as an ingredient that can support skin immune defenses from the inside.