Exploring the gut-skin axis

Research is continuously demonstrating the importance of the gut microbiome in health. However, a new emerging area of interest is skin health, which not only has its own microbiome, but also could be affected by the microbes residing in the gut. In this article, we will explore the gut-skin axis and the mechanisms that can promote skin homeostasis.

The skin Microbiome

The skin is considered a barrier organ, that along with the skin microbiome, protects the body against external stressors and threats (Whiting et al., 2024). Much like the gut microbiome, the skin microbiome develops from birth and as age progresses, consists of lower quantities of beneficial bacteria (Haykal et al., 2024). Generally, a healthy skin microbiome stays relatively constant, however, transient microorganisms, which are microbes that live temporarily on the skin, will inhabit for a few hours to days, but do not usually have a lasting effect on the skin’s environment or microbiome (Pistone et al., 2021).

The skin microbiome contains both beneficial and less beneficial microbes, and it’s a balance of these microbes that is considered optimal for health. Whilst there are individual variations in what constitutes as healthy, it is important that beneficial microbes exist in adequate quantities to support a balanced skin microbiome and skin health (Ito and Amagai., 2022). For both the gut and skin microbiomes, there are lots of factors that can impact their compositions, and these can be extrinsic or intrinsic. For the skin, extrinsic factors, such as antibiotic overuse, washing, diet, anti-inflammatory therapies, chemotherapy or radiotherapy, and intrinsic factors such as hormonal fluctuations, can change the composition of the skin microbiome (Skowron et al., 2021).

The gut-skin axis

The gut-skin axis is a term used to describe the connection between the gut microbiome and skin (Thye et al., 2022). The gut microbiome is known to have a far-reaching effect on health, influencing not only digestive wellbeing, but also cognition and immunity (Mohajeri et al., 2018). Whilst skin is a relatively new area that researchers are exploring, it is known that the state of the gut, along with the interactions that take place there, can also impact the health of the skin.

Emerging research suggests that the gut microbiome’s effect on systemic immunity is what enables the interaction with the skin microbiome and influences skin health (Mahmud et al., 2022). The fermentation of dietary fibre by gut microbes results in the production of beneficial metabolites, such as short chain fatty acids (SCFAs), which directly interact with immune cells (Wang et al., 2024). SCFAs play an important role in immune cell and mucosal barrier function and can control the size and function of regulatory T-cells (Treg cells), which are important for suppressing inflammation (Egawa et al., 2017; Whiting et al., 2024). Whilst both the skin and gut microbiome produce SCFAs, changes in the microbial community in the gut, known as dysbiosis, can negatively impact their production and subsequently lead to an altered immune response. In turn, this can trigger a cascade of problems, such as allergies, acne and atopic dermatitis (Mahmud et al., 2022).

Prebiotics and Probiotics

Prebiotics and probiotics are quickly becoming well-known ways of supporting a balanced gut microbiome (Cunningham et al., 2021). Because the composition of the gut microbiome has the capacity to influence skin homeostasis, consuming prebiotics and probiotics orally to promote a favourable composition of gut microbes could be a possible therapeutic for skin health. Whilst research is in its early stages, studies have shown that oral probiotics comprising of the strains Lactobacillus Acidophilus, Lactobacillus Delbrueckii subspecies Bulgaricus and Bifidobacterium Bifidum can be effective in treating acne (De Almeida et al., 2023). Research also shows that probiotics may have photoprotective benefits to protect the skin from harmful UV rays, may reduce oxidative stress and inhibit inflammation which may be beneficial in cases of dermatitis (De Almeida et al., 2023).

There is currently limited literature on the effect of prebiotics on skin health, however, as mechanistically they work directly to increase the quantity of beneficial species of bacteria, such as lactobacillus and bifidobacteria, there is potential for prebiotics to play a role in skin health via the gut-skin axis.

The Takeaway

Whilst the gut-skin axis is a new emerging area of interest, there is evidence to suggest that modulating the gut microbiome via probiotics and prebiotics could be an effective way to support skin health. By collaborating together, the microbiomes residing on the skin and in the gut, in tandem with the immune system, could promote skin homeostasis.

References

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