Trying to let go of highly oily and sugary foods, like our beloved chocolate, to avoid skin problems such as acne has been a reality for many. It is well known that our diet has a big impact on our overall health. However, diet is only one of the characters involved in the complex story of the gut-skin axis. In which microbiota, host immunity, and metabolic products seem to be the main leads.
Both the human skin and intestine are in touch with the outside environment and harbor a variety of commensal and pathogenic microorganisms living in symbioses with the host (microbiota) [1]. More and more we discover that these systems and the microorganisms composing them collaborate with each other to keep homeostasis, a well-balanced body condition.
The gastrointestinal microbiota participates in energy homeostasis, metabolism, gut epithelial health, immunologic activity, and neurobehavioral development. Hence, disturbances of this microenvironment may lead to diseases like inflammatory bowel disease, asthma, obesity, metabolic syndrome, cardiovascular disease, immune‐mediated conditions, neurodevelopmental conditions, and the list goes on [2]. Diet is one of its main regulators - well, that gives some backup to the “we are what we eat” saying- together with age, lifestyle and the use of antibiotics [3].
Adding one more to the bunch, gut microbiota also influences epidermal differentiation through a not yet well-elucidated immunological route. Some metabolites produced by gut bacteria such as butyrate, polysaccharide A and retinoic acid promote anti-inflammatory pathways, while others are involved in pro-inflammatory reactions. Besides having an indirect effect on the skin, bacteria, and their metabolites may disrupt cutaneous homeostasis by accessing the bloodstream and accumulating in the skin in case of intestinal barrier disturbance [4].
Studies have already linked certain gastrointestinal bacteria (e.g. Lactobacillus and Bifidobacterium) with better outcomes or protection against cutaneous disorders such as psoriasis, rosacea, atopic dermatitis, and acne [5]. Chances are that if you grab the nearest probiotic food product around, you are going to find the genera cited above in it. This is no coincidence since these two are well-known human-friendly genera for carrying benefits to human health.
And speaking of probiotics, their use by children and adults of different ages and genders under clinical evaluation already showed they are a promising therapeutical approach. They improved lesions and severity of acne and reduced the severity of atopic dermatitis and atopic eczema. They even enhanced skin hydration, shine and elasticity, reduced wrinkle depth, and improved hair follicle [5].
Gut microbes also produce GABA, acetylcholine, dopamine, serotonin and other neurotransmitters that may modulate skin function through the nervous system [6]. This brings a third member to the equation: The brain! Adding a completely new level of complexity to this relation, and, with other factors, creating the gut-skin-brain axis.
The effects and mechanisms pertaining the subject still need to be better investigated, nevertheless, in these findings there is considerable potential for new therapies for a myriad of dermatological and intestinal disorders.
Meanwhile, it is good to remember that besides being responsible for digestive functions and -apparently- foreboding feelings, your gut is a crucial part of your body and when treated with care it will make your skin bloom. Actually, due to its systematic ramifications, you could very well feel like a flourishing garden.
References:
[1] Coates, M. et al. (2019). The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems. Frontiers in Immunology, 10(), 2950–. doi:10.3389/fimmu.2019.02950
[2] Barko, P. C., et al. (2017). The Gastrointestinal Microbiome: A Review. Journal of Veterinary Internal Medicine (Vol. 32, Issue 1, pp. 9–25). https://doi.org/10.1111/jvim.14875
[3] Requena, T., & Velasco, M. (2021). The human microbiome in sickness and in health. Revista Clínica Española (English Edition) (Vol. 221, Issue 4, pp. 233–240). https://doi.org/10.1016/j.rceng.2019.07.018
[4] Salem, I., et al. (2018). The Gut Microbiome as a Major Regulator of the Gut-Skin Axis. Frontiers in Microbiology (Vol. 9). https://doi.org/10.3389/fmicb.2018.01459
[5] Mahmud, Md. R. et al.(2022). Impact of gut microbiome on skin health: gut-skin axis observed through the lenses of therapeutics and skin diseases. Gut Microbes (Vol. 14, Issue 1). https://doi.org/10.1080/19490976.2022.2096995
[6] Lyte, M. (2014). Microbial Endocrinology and the Microbiota-Gut-Brain Axis. Advances in Experimental Medicine and Biology (pp. 3–24). https://doi.org/10.1007/978-1-4939-0897-4_1