Live or dead bacteria in Skincare?

A summary on the latest publication ">>> Lactobacillus reuteri DSM 17938-A comparative study on the effect of probiotics and lysates on human skin." by the author Johanna Gillbro, www.skinomeproject.com, (co authors: Khmaladze I, Butler É, Fabre S). It was a collaborative study together with BioGaia and Oriflame.

The microbiome has been a hot subject within the gut area for the last 10 years. The gut microbiome has been investigated for over 10 years and side effects such as weight loss, effect on mental health, treatment of C. difficile infection etc. have been correlated to a modulation of the gut microbiome.

However, the microbiome of the largest organ of our body, our skin, is relatively unexplored even though it is home to a microbiota composed of millions of bacteria, viruses and fungi.

We are just starting to understand the role of our skin microbiome and we know that human skin microbiota influences general skin health (here you can find more about microbiome and skin diseases). It plays important parts:

• It acts as a defence against unwanted pathogens and opportunistic microorganisms, by producing antimicrobial and anti-inflammatory compounds.
• It is involved in regulating host inflammation.
• It supports the skin barrier.
• It plays a role in the skin aging process.

Probiotics and their use in food

For over a century, probiotics (live bacteria with health benefits) have been used in food for improving gastro-intestinal health. In gut related issues, probiotics and other microbiome technologies are now competing with traditionally used medications. Now, there is a renewed interest in using live bacteria also in the management of different inflammatory and infectious diseases, dominated by urogenital tract, oral health and most recently an increased awareness in dermatology.

In cosmetics, the hype of probiotics has reached the market.

However, the word probiotics most often refers to killed or inactivated lactobacillus bacteria.

There are a only  few products on the market developed with probiotics i.e. live bacteria – and the probiotics used are Lactobacillus or a bacterium found in soil, Nitrosomonas eutropha (AOBiome).

In this study, we aimed to investigate the effect of the live bacterium Lactobacillus reuteri compared with lysates (lysed, dead bacterial material) thereof. The effects of these two bacterial preparations were tested in a reconstructed human epidermis and in a native skin model. We had a look at the anti-inflammatory, anti-microbial and barrier function properties in human skin.

This specific strain used in this study (L. reuteri DSM 17938) is widely associated with improving gastro-intestinal health through oral administration with limited data published in relation to its potential effect on skin health.

Interestingly, our results showed that live bacteria showed additional effects compared to lysed bacteria of L. reuteri. Both forms of L. reuteri possessed anti-inflammatory effects tested on UV induced inflammatory cytokines (IL-6 and IL-8) and an impact on skin barrier. Additionally, live L. reuteri had an inhibitory action against pathogenic skin bacteria.

These results indicate that the live form of L. reuteri DSM 17938 could be used in management of skin issues related to photoaging, bacterial overgrowth skin dysbiosis and skin hydration. The lysates could be used in skincare where an anti-inflammatory action is needed.

In conclusion, this study shows that both live and lysed bacteria of L. reuteri exert anti-inflammatory effects upon topical application on human skin. However, live bacteria, real probiotics, exert additional anti-microbial effect compared to postbiotics. These findings open for more exploration of probiotics for treatment of different skin inflammatory conditions such as atopic dermatitis, rosacea and acne, which could potentially limit the usage of corticosteroids, antibiotics, benzoyl peroxide and salicylic acid.

Further studies are needed to further explore this hypothesis.

An additional interesting article on this topic: Pro- and prebiotics on the skin? An interview with Dr. Cath O'Neill.