When skin problems are considered, often a topical approach is recommended. This means that people reach for creams or lotions which can play a role in keeping the skin hydrated and supple. This post explores how the gut-skin axis could be utilised for skin health.

Creams and lotions with SPF and UVA protection are important to minimise sun damage and premature skin ageing. It’s acknowledged that vitamins and minerals have an important role to play in skin health such as vitamin A, vitamin C, riboflavin, niacin, pyridoxine, vitamin E, zinc and selenium. This can be through diet or the addition of vitamins to creams and lotions. However, the evidence is not fully conclusive about the use of creams to reduce skin ageing. A dietary approach could contribute towards keeping skin healthy (1).

The above nutrients that are found in a diet rich in fruits and vegetables which are also high in fibre. It’s less recognised that fibre, particularly fermentable fibre may improve skin health. Fermentable (prebiotic) fibre feeds the good bacteria in the gut microbiome, which is important as the gut microbiome is linked not only to gut, immune and cognitive health but may also affect the skin .
The collection of bacteria, viruses, fungi, and protozoa colonising in the gastrointestinal tract make up the gut microbiome. The host’s immune system is influenced by the gut microbiome through immune tolerance of environmental and dietary antigens and provides protection against pathogens. The gut microbiome protects against pathogens directly by competitive exclusion and indirectly by triggering immune responses. Through these complex immune mechanisms, the gut microbiome can influence regulatory processes, the allostasis and homeostasis, of distant organs such as the skin (2).

The skin is a barrier organ, that along with the skin microbiome, protects the body against external threats. A healthy skin microbiome stays relatively constant based on the resident bacteria. Transient microorganisms will inhabit the skin for a few hours to days but do not tend to change the environment. Extrinsic factors such as antibiotic overuse, washing, anti-inflammatory therapies, chemotherapy or radiotherapy can change the composition of the skin microbiome. There are intrinsic factors that can change the skin microbiome, an example being excess sebum production during puberty or the influence of the gut microbiome (3). The good bacteria on the skin, also known as the commensal bacteria, must predominate. Much like the gut microbiome, the skin microbiome develops from birth and ageing skin has not so many of the good bacteria. It is another reason to take care of skin while young to help maintain this profile, acting as a shield to protect the body from external aggressions (3).
The human skin microbiome varies across individuals and body sites because three eco-systems on human skin exist: sebaceous, moist and dry. Dry skin sites have more interpersonal variation of microbes than moist or sebaceous sites. A variety of intrinsic and extrinsic factors affect the skin ecosystems (4).

Interaction in gut-skin axis

The gut microbiome contributes to skin allostasis – the restoration of homeostasis after a disturbance or stressor (2). It is thought that the gut microbiome’s effect on systemic immunity is what causes the interaction with the skin microbiome and skin health. Host physiology and extrinsic factors affect the skin microbiome composition. Once intrinsic factors stabilise, the skin microbiome remains stable, but medications and lifestyle are associated with shifts (4). SCFAs (short chain fatty acids), particularly butyrate, suppress immune responses by processes such as inhibiting inflammatory response proliferation and cytokine secretion.

An interaction within the gut-skin axis appears to exist in eczema cases where the gut barrier function plays a role. Antigen transfer through the gut barrier is seen in children with atopic eczema and probiotic interventions are considered to restore the gut-barrier function (5). The anti-inflammatory effects elicited by the SCFA production as a result of prebiotic consumption could be beneficial to those who suffer from atopic dermatitis (AD) otherwise known as eczema. There is also evidence that the immunomodulatory effect of probiotics can reduce inflammation in AD (6). Furthermore, there is potentially a preventative role in using probiotics and prebiotics to prevent acne. The use of prebiotics has shown to inhibit growth of A. Vulgaris and P. acnes and to facilitate growth of beneficial bacteria such as lactobacilli (7).

Psoriasis is an immune mediated chronic inflammatory skin disease and its relation to the gut microbiome is the gut microbiota alterations in people with psoriasis. Akkermansia muciniphila was reduced, and Clostridium citroniae was increased in a group with psoriasis compared to healthy control. Psoriasis has a similar immune response and inflammatory cytokine profile to obesity and inflammatory bowel disease, suggesting the pathogenesis of the psoriasis (8). Rosacea is the fourth skin condition – a chronic inflammatory dermatosis that affects the face. It is thought to be caused by abnormal neurovascular response and dermodex mites that inhabit healthy skin. Alterations in the gut microbiota have additionally been identified in rosacea pathogenesis. Reduced abundance of Peptococcaceae family, Methanobrevibacter, Slackia, Coprobacillus, Citrobacter, and Desulfovibrio were seen in a small cohort study. Although the specific pathogenesis is not confirmed between skin conditions and the gut microbiome, there are associations that infer that further research is necessary to determine a causal link (9).

Eating for skin health

In a study where healthy women consumed fermented milk containing B. breve, alongside galactooligosaccharide, hydration level decreases were prevented in the skin (10) which was thought to prevent skin ageing. There is limited research on the use of prebiotics and probiotics to maintain skin health. However, the current research into the brain-gut-skin axis suggests associations. More research should be conducted into how a gut microbiome ‘friendly’ diet can influence skin health. Eating a diet high in fruit and vegetables for their antioxidant capacity remains to be the recommendation for maintaining a balanced diet and healthy, youthful skin (11) and these foods may also hold the key to the gut-skin axis too.

In summary, the diet can play a role in skin health. Consuming a variety of plant-based foods provides a wider variety of vitamins, minerals and fibres that could provide additional benefit to skin health by feeding the gut microbiome. While a food based approach is the ideal method to target the gut microbiome, the clinical research showing the beneficial effects of probiotic use on skin conditions (6,7,8,9) suggests that this could be an additional intervention to traditional approaches, or the use of prebiotic supplements to compliment a dietary approach.

References

1. https://www.bda.uk.com/resource/skin-health.html
2. Salem, I., Ramser, A., Isham, N. and Ghannoum, M.A., 2018. The gut microbiome as a major regulator of the gut-skin axis. Frontiers in microbiology, 9, p.1459.
3. Dréno, B., Araviiskaia, E., Berardesca, E., Gontijo, G., Sanchez Viera, M., Xiang, L.F., Martin, R. and Bieber, T., 2016. Microbiome in healthy skin, update for dermatologists. Journal of the European Academy of Dermatology and Venereology, 30(12), pp.2038.
4. Prescott, S.L., Larcombe, D.L., Logan, A.C., West, C., Burks, W., Caraballo, L., Levin, M., Van Etten, E., Horwitz, P., Kozyrskyj, A. and Campbell, D.E., 2017. The skin microbiome: impact of modern environments on skin ecology, barrier integrity, and systemic immune programming. World Allergy Organization Journal, 10(1), p.29.
5. Kalliomäki, M., Salminen, S., Poussa, T. and Isolauri, E., 2007. Probiotics during the first 7 years of life: a cumulative risk reduction of eczema in a randomized, placebo-controlled trial. Journal of Allergy and Clinical Immunology, 119(4), p.1019.
6. Rusu, E., Enache, G., Cursaru, R., Alexescu, A., Radu, R., Onila, O., Cavallioti, T., Rusu, F., Posea, M., Jinga, M. and Radulian, G., 2019. Prebiotics and probiotics in atopic dermatitis. Experimental and therapeutic medicine, 18(2), pp.926.
7. Lolou, V. and Panayiotidis, M.I., 2019. Functional role of probiotics and prebiotics on skin health and disease. Fermentation, 5(2), p.41.
8. Tan, L., Zhao, S., Zhu, W., Wu, L., Li, J., Shen, M., Lei, L., Chen, X. and Peng, C., 2018. The Akkermansia muciniphila is a gut microbiota signature in psoriasis. Experimental dermatology, 27(2), pp.144.
9. Nam, J.H., Yun, Y., Kim, H.S., Kim, H.N., Jung, H.J., Chang, Y., Ryu, S., Shin, H., Kim, H.L. and Kim, W.S., 2018. Rosacea and its association with enteral microbiota in Korean females. Experimental dermatology, 27(1), pp.37.
10. Kano, M., Masuoka, N., Kaga, C., Sugimoto, S., Iizuka, R., Manabe, K., Sone, T., Oeda, K., Nonaka, C., Miyazaki, K. and ISHIKAWA, F., 2013. Consecutive intake of fermented milk containing Bifidobacterium breve strain Yakult and galacto-oligosaccharides benefits skin condition in healthy adult women. Bioscience of microbiota, food and health, 32(1), pp.33.
11. Schagen, S.K., Zampeli, V.A., Makrantonaki, E. and Zouboulis, C.C., 2012. Discovering the link between nutrition and skin aging. Dermato-endocrinology, 4(3), pp.298.