The skin microbiota is described in countless articles as a loyal and powerful ally for the skin. Indeed, the skin microbiota keeps the skin clean and radiant by removing waste proteins and lipids. It also produces anti-microbial peptides and acids that keep pathogens away. Recent scientific investigations discovered that the skin microbiota supports the skin beyond our imagination. Members of the skin microbiota communicate with our immune cells which increases the resistance of our skin. Antioxidants from the first categories are produced by the protective microbiota. These antioxidants prevent the formation of free radicals and protect the skin from premature aging. Even the inflammation process during sun exposure is regulated. Last, but not least, a strain of S. epidermidis produces 6-N hydroxyaminopurine. This substance reduces and prevents the formation of cancer cells.
It is obvious that the loss or damage of such a beneficial microbiota is detrimental to the health of the skin. A disturbed skin microbiota leaves the skin alone and unprotected in a cruel world. The skin becomes sensitive, stressed and in severe cases becomes infected. In literature it is described that the skin microbiota is damaged when exposed to UV light and to anti-microbial compounds; This study specifically examined how much the skin microbiota is damaged by UV-exposure, the use of ethanol, preservatives, surfactants, and glycolic acid. It was also measured if Inulin has a supporting effect in all these circumstances. Finally, the recovery effect of inulin on an acne disturbed skin microbiota was quantified.
The number of microorganisms was counted by cultivation on agar-TTC nutrient. The skin microbiota was profiled through detailed interpretation of the sequencing-based 16S or IST profiling experiment. Short sequence reads were generated using the Illumina MiSeq platform.
Inulin was used as it is a well-established prebiotic. A prebiotic supports protective microorganisms but does not support opportunistic or accidentally present organisms. In this way the protective microbes can recover more efficiently.
It was found that UV light killed the skin microbiota in less than 15 minutes for 99.99%. A timid recovery started only after 4hours. When the UV-exposed skin was treated with Inulin, already 80% of the skin microbiota was recovered after 4hours. Without the use of inulin, the skin was substantially invaded by microorganisms from the environment. Similar results were observed when the skin was treated with ethanol, glycolic acid or with a strongly preserved cream. A significant restoring effect of the protective microbiota has been observed with the use of inulin in all these cases.
Cleaning a healthy skin with surfactants disturbed the skin microbiome up to 38%. When the surfactants were combined with Inulin, the disturbance on the skin microbiome was negligible.
A facial wash containing sodium cocoyl glutamate was tested on an acne prone skin. It was observed that the surfactant increased the presence of the acne-pathogens, such as C.acnes and S. epidermidis, while the protective microbiome was diminished with 60%. When the surfactant was combined with Inulin, the acne pathogens were diminished with 50%, while the protective microorganisms were increased with 40%. All the above tests were performed in-vivo. In all these tests the skin microbiota was seriously challenged. It turned out that Inulin was able to support and to improve the recovery of this skin microbiota in both leave on and rinse off conditions. Although inulin was not able to protect the skin microbiota from UV light, it was also able to effectively shield the skin microbiota from harmful ingredients in all the other circumstances. Therefore, Inulin is an interesting support for the skin microbiota and indirectly for the skin: an ally for our ally.