The Skin Microbiome
The skin inside & out
The primary role of skin is to serve as a physical barrier that protects our body from potential assault of foreign organisms and toxic substances. The skin is an interface with the outside environment and as such performs as an ecosystem composed of living biological and physical components that occupy diverse microorganisms.
We now know there is a vast diversity of microorganisms that colonise on the skin, known as the skin microbiome. This includes bacteria, fungi, viruses and arthropods. Changes within the population of these colonies are characterized in many skin diseases such as; acne, dermatitis, rosacea and psoriasis.
Within the body, microbial cells outnumber human cells by at least ten times more in number. The microbiome modulates disease, influences biological processes and is vital for immunity. Unfortunately, the microbiome is a prime target for manipulation and can influence the host’s health and contribute to disease processes, so we have to assume the same can be said for the skin’s microbiome due to its vulnerability to the environment, the use of chemicals and possible lack of correct nutrition.
There are four dominant phyla (classifications) of bacteria that reside on the skin as commensal (friendly) bacteria;
These four dominant phyla also constitute the microbiota found in the gastrointestinal tract although the proportion of phyla differ with Actinobacteria more abundant on the skin and Firmicutes and Bacteroidetes more abundant in the gastrointestinal tract.
The variability of these bacteria strains can vary between individuals with Staphylococcus, Propionibacterium and Corynebacterium found in varying numbers depending on the skin site. Hair follicles, sudoriferous (both eccrine and apocrine) glands, and sebaceous glands are contributing sites that contribute to the cutaneous areas, and where we find subsets of these bacterias residing.
The skin and GIT microbiome research will soon inform a precise and bespoke approach in the management and treatment of skin diseases as we come to understand this delicate and vulnerable structure.
The skin microbiome and acne
Lipophilic bacteria like propionibacterium and its strains colonize in the skin’s more sebaceous areas such as the back, face, and behind the ears. This bacteria hydrolyzes the triglycerides found in sebum and release fatty acids that then acidify the skin.
The released free fatty acids allow bacteria strains to adhere and aids in colonization within the sebaceous gland activating and inducing production of pro-inflammatory cytokines. These free fatty acids contribute to the acidic pH of the skin with common bacterias such as; propionibacterium, staphylococci and corynebacteria thriving in this environment. It is when there is an imbalance to either side of a strain that we see skin disorders and infections.
So what is the best treatment plan? Topically, providing essential nutrients and maintaining the skin’s barrier to allow for commensal bacterial to provide skin health is key. Topical ingredients that have shown to provide improvement with skin conditions such as acne include; Niacinamide/vitamin B3, Retinoids/vitamin A, AHA/BHA with a high pH so as not to remove the barrier but to maintain skin acidity. Avoid harsh ingredients such as Sodium Lauryl Sulphate & Sodium Laureth Sulphate as these are surfactants that remove almost all traces of sebum, leaving the skin without a barrier to accommodate commensal bacteria.
Nutritionally, rebuilding a healthy microbiome, particularly after antibiotic therapy, is key. Dysbiosis is characterised by a reduction or loss of core commensal bacteria level along with an overgrowth of pathogenic bacteria with reduced microbiome function which may lead to inflammatory skin conditions such as acne, or even rosacea.
Providing your body with pre and probiotics will allow the diversity of commensal bacteria to be re-established and in turn function correctly with regulating immunity, promoting chemical detoxification, improving metabolism and improve skin conditions.
A plant-based diet has been shown to improve the microbiome diversity along with exercise and contact with nature and even your pets.
Prebiotics provide an environment so as probiotics can thrive and repopulate. Essentially prebiotics are plant fibres (that ferment by anaerobic bacteria in the colon) therefore; naturally exist in many foods you may already eat.
- Green leafy vegetables
- Raw garlic
Probiotic foods generally come from fermented foods and are essential for digestion and immunity. A diversity of friendly bacteria repopulate when probiotic foods are consumed and this then improves the skin and general health and wellbeing. Foods to consume when looking at providing probiotics include;
- Cultured vegetables – Kimchi, Sauerkraut
- Yoghurt (grass-fed & organic cows, sheep, goats)
If you feel you are unable to obtain adequate amounts of pre or probiotics from your food, then consulting with a reputable natural health practitioner is recommended for correct diagnosis and prescription of supplementation along with dietary changes.
Brandwein, M., Steinberg, D., Meshner, S. (2016). Microbial biofilms and the human skin microbiome. Npj Biofilms and Microbiomes. doi: 10.1038/s41522-016-0004-z
Grice, EA. (2014). The skin microbiome: potential for novel diagnostic and therapeutic approaches to cutaneous disease. Semin Cutan Med Surg. 33(2):98-103
Grice, EA., and Segre, SA. (2011). The skin microbiome. Nat Rev Microbiol. 9(4): 244-253. doi:10.1038/nrmicro2537