Published: May 30, 2016
Author: Melissa Peterson AdvDipHSc(Nat) GradCertEvBdPrac
“Acne and eczema are both traceable to this fountainhead of diseases ... if in a case of urticaria we look to the intestinal tract, why not in eczema and acne?” Milton H. Mack, Illinois Medical Journal 1911.1
Evidence of the gut-brain axis has been developing for many years. However, more recently there has been a re-emergence of the gut-skin axis theory from its discovery 80 years ago.
The original research, by two dermatologists, linked gut dysfunction and stress-induced alterations of the gut microbiota to increased intestinal permeability, which could lead to systemic and local skin inflammation. They theorised that emotional states were linked to these gut microbial changes and resultant skin conditions. Hence, the concept of the gut-brain-skin axis was developed.1
Inflammatory bowel diseases strengthen the evidence for the gut-skin axis, with up to 40% of patients experiencing extraintestinal manifestations; the skin being the most commonly affected organ.2
Evidence also shows that up to 40% of acne sufferers have hypochlorhydria, which has been linked to increased intestinal permeability and small intestine bacterial overgrowth (SIBO). Increased intestinal permeability can lead to enhanced immune and lipopolysaccharide (LPS) reactivity.1 One study showed SIBO is 10 times more prevalent in acne rosacea patients than controls.3
Many skin conditions, including acne vulgaris, acne rosacea, psoriasis and atopic dermatitis, have increased inflammatory or immune activity, with links to dysbiosis and increased gut pathogen overgrowth.
A recent review showed Staphylococus aureus, which induces long-term inflammation, may be associated with psoriasis and acne.4 More research is required; however the link between pathogens and skin conditions is not new, with antimicrobial treatments being the mainstay treatment for acne for decades. With antibiotic resistance prevalent, probiotics are now being explored.1
In the first experimental study of its kind, probiotics reduced stress-induced neurogenic skin inflammation, with observations showing potential for skin homoeostasis, skin inflammation, hair growth and peripheral responses to perceived stress.5
Probiotics may also affect skin health by maintaining the intestinal barrier, regulating and reducing sebum production of acne through cannabinoid receptors and substance-P, influencing nutrient and omega-3 absorption, and increasing stress resiliency through the regulation of the gut-brain axis.1
The cells of the gut, brain and skin are linked by common embryonic origin, with shared signalling and innervations. Skin conditions are often complex, with no single avenue of pathogenesis; therefore, ‘We must approach this exciting yet largely hypothetical landscape, the gut-brain-skin triangle, with scientific vigour.1