Beneath the skin surface
We usually think of skin as simply a protective layer between us and the outside world, but it’s doing so much more behind the surface. It’s actually an organ, one that shares its roots with the nervous system, which is why it’s packed with nerve endings to help us sense our environment. But that’s not all. The skin isn’t just a barrier; it’s also a key player in sensation, immune functioning and even elimination, quietly working to keep us healthy every day. In recent years, research has revealed intricate relationships between skin health, digestion, and other body systems, with the gut-skin axis being a key player.
Organ of Defense
The skin is the body’s largest and most external barrier to the outside world. Its keratin and mucus layers act as powerful shields, protecting against acids, bases, toxins, and microorganisms. Beneath these layers, the skin is rich with immune and microbial cells that not only defend but also help train the immune system, playing a vital role in maintaining overall health.
Epithelial cells play a critical role in continuously training the immune system to distinguish between harmful invaders and harmless or beneficial substances. This immune priming begins early in life, establishing self tolerance, a process that, when disrupted, may contribute to allergies and autoimmune disorders.
Organ of Sensation
The skin is packed with nerve endings that allow it to send detailed information about the body’s external environment to the brain. These sensory receptors detect temperature changes, moisture, texture, touch, and motion, helping us navigate the world. They also play a critical role in sensing pain, which protects us from harm. This sensory function is essential not only for safety but also for fostering curiosity, pleasure, and a fully embodied experience of the world.
Organ of Elimination
The skin is a remarkable detox organ, equipped with enzymes that neutralize harmful chemicals and reactive oxygen species, similar to those found in the liver (the body’s primary detoxifier). Sweat plays a key role in this process by eliminating water-soluble substances.
Activities like saunas and exercise enhance this process, promoting sweat-mediated elimination of toxins while improving circulation, which contributes to overall detoxification and health. Studies have shown that sebum production is intricately linked to diet and metabolic conditions, with calorie deprivation leading to decreased sebum output, while high-fat diets significantly increase it.
Gut-Skin Axis
The gut-skin axis refers to the connection between the gastrointestinal system and the skin. Recent studies have highlighted that gut barrier health is key to maintaining a healthy skin barrier. In cases of leaky gut, where the integrity between gut cells is disturbed, harmful substances leak into the bloodstream. This inflow triggers a protective immune response, leading to cytokine release and systemic inflammation. This inflammatory state has been correlated with various dermatological conditions, dermatitis the most well researched so far.
Skin Microbiome
The skin microbiome has become a focal point in understanding skin health and its relationship with the immune system. An imbalance in this delicate ecosystem has been linked to various skin conditions, including acne vulgaris, atopic dermatitis, psoriasis, rosacea, dandruff, seborrheic dermatitis, alopecia, and hidradenitis suppurativa, to name a few. Interestingly, linking back to the gut-skin axis, members of the gut microbiome can influence the skin microbiome, immune compounds and skin diseases. Addressing microbiome health is increasingly recognized as a vital step in managing these conditions and supporting skin overall.
Skin cells are continuous with digestive cells, so it should come as no surprise that these two tissues are so intimately interrelated.
Nutritional Deficiency and Skin Health
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Follicular Hyperkeratosis : This is a hallmark condition of vitamin A deficiency characterized by dry, rough, and bumpy skin, especially on the arms, thighs, and buttocks.
Dry Skin: Vitamin A deficiency impairs the skin's ability to retain moisture, leading to dry, scaly, and sometimes itchy skin.
Acne: Although often linked to excess sebum production, vitamin A deficiency may contribute to acne by altering skin cell turnover (promoting clogged pores).
Impaired Wound Healing and increased susceptibility to infections: Vitamin A plays a vital role in skin repair. Its deficiency can delay wound healing and increase the risk of infections.
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Vitamin B2 (Riboflavin): Symptoms include cracked corners of the mouth, oily and scaly patches around the nose, mouth, and forehead (seborrheic dermatitis).
Vitamin B3 (Niacin): Symptoms include redness, scaling, and a rough texture, often developing into a condition called pellagra, characterised by dark, scaly patches on sun-exposed areas.
Vitamin B7 (Biotin): Symptoms include dermatitis, eczema, and rashes, especially around the eyes, nose, and mouth.
Vitamin B12: Symptoms may include hyperpigmentation (dark pigmentation) and vitiligo (loss of skin pigment).
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Increased susceptibility to eczema and atopic dermatitis.
Vitamin D deficiency is also linked with psoriasis, a condition causing red, scaly patches on the skin.
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Petechiae: Small, pinpoint red or purple spots caused by blood leaking from weakened capillaries.
Purpura and Ecchymoses: Larger bruises appearing spontaneously, especially on the legs.
Hyperkeratosis: Thickened, rough skin often accompanied by coiled hairs.
Dryness and Scaling: The skin may become dry, flaky and peeling
Poor Wound Healing Skin Fragility
References
1. Zhou, S. S., Li, D., Zhou, Y. M., & Cao, J. M. (2012). The skin function: a factor of anti-metabolic syndrome. Diabetology & metabolic syndrome, 4(1), 15. https://doi.org/10.1186/1758-5996-4-15
https://pubmed.ncbi.nlm.nih.gov/22537765/
2. Dayel SB, Hussein RS. Vitamin Deficiencies and Their Impact on Skin Function. International Journal of Biomedicine. 2023;13(2):205-209. doi:10.21103/Article13(2)_RA4
3. Wiseman N. Fundamentals of Chinese Medicine. Paradigm Publications. 1996. https://www.abebooks.com/9780912111520/Fundamentals-Chinese-Medicine-Wiseman-Nigel-0912111526/plp
4. Sunhee, Lim., Jihye, Shin., Yunhi, Cho., Kun-Pyo, Kim. (2019). Dietary Patterns Associated with Sebum Content, Skin Hydration and pH, and Their Sex-Dependent Differences in Healthy Korean Adults.. Nutrients, 11(3):619-. doi: 10.3390/NU11030619 https://pubmed.ncbi.nlm.nih.gov/30875764/
5. De Pessemier, B., Grine, L., Debaere, M., Maes, A., Paetzold, B., & Callewaert, C. (2021). Gut-Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions. Microorganisms, 9(2), 353. https://doi.org/10.3390/microorganisms9020353
6. Shahnawaz, Mohammad., Md, Rezaul, Karim., Sajid, Iqbal., Jung, Hyeok, Lee., Ramya, Mathiyalagan., Yeon, Ju, Kim., Dong, Uk, Yang., Deok‐Chun, Yang. (2024). Atopic dermatitis: Pathophysiology, microbiota, and metabolome – A comprehensive review. Microbiological Research, 281:127595-127595. doi: 10.1016/j.micres.2023.127595. https://pubmed.ncbi.nlm.nih.gov/38218095/
7. Sadowsky, R. L., Sulejmani, P., & Lio, P. A. (2023). Atopic Dermatitis: Beyond the Skin and Into the Gut. Journal of clinical medicine, 12(17), 5534. https://doi.org/10.3390/jcm12175534. https://pubmed.ncbi.nlm.nih.gov/37685600/