Sebum and Epidermal Surface Lipids
Part 1
How can we use our knowledge of the skin’s anatomy to approach skincare in a physiologically supportive way?
Understanding the anatomy of our skin can allow us to support it in a foundational and holistic way. When we understand the fragments that make up our skin and the functions of each - we can choose to use products and methods that mimic what is physiologically appropriate. The epidermal surface lipids play an essential role in the skin’s health and function - providing a barrier against the movement of water and electrolytes, protecting against microorganism invasion, thermoregulation, and more.
There are three main layers within our skin: the epidermis, dermis, and subcutaneous tissue:
The epidermis contains keratinocytes, melanocytes, carries out new skin cell production, and barrier formation.
Within the dermis will be sweat glands, sebaceous glands, hair follicles, blood vessels, and nerves.
The subcutaneous layer is made up of connective tissue and fat cells.
What is sebum?
Human sebum is a substance excreted by the sebaceous glands in the epidermis. It provides moisture, acts as a barrier against harmful bacteria and water loss, provides the basis for thermoregulation and the transport of fat soluble antioxidants like vitamin E. It is a mixture of non-polar lipids, trivglycerides, wax esters, squalene, fatty acids, and cholesterol. It provides over 90% of the lipids on the skin. The production of sebum is regulated by both neural and endocrine controls. The health of your skin hinges on the functional production of sebum.
Dysregulated sebum production can have a cascading effect on the health of the skin. Lack of, or overproduction of sebum can impede water repulsion, proper hair growth, and thermoregulation (Zheng et al.) Sebaceous gland atrophy is directly related to hair loss and dermatological conditions like acne, atopic dermatitis (eczema), rosacea, etc. With ideal sebaceous gland activity, lipids can identify which foreign organisms are an enemy and which are desirable.
What causes sebaceous gland dysfunction?
1) Using barrier-stripping products like alcohols, acids, harsh cleansers, and some clays:
Using products that strip the barrier can leave your skin defenseless against harmful bacteria, dry out the skin, and cause the sebaceous glands to overproduce to compensate - which can lead to clogged pores (acne)
2) HPA axis dysfunction; Excess cortisol proliferation:
Since the sebaceous glands are regulated by the endocrine system, they become sensitive to fluctuations in cortisol and adrenaline - excessive cortisol due to internal or external stressors causes an increase in sebum production beyond what is necessary.
3) Hormone imbalances - estrogen dominance, high androgens, or thyroid disruption:
High levels of androgens (steroids directed by the adrenal cortex and ovaries in females) cause sebaceous glands to enlarge and potentially overproduce, leaving pores susceptible to clogging.
4) Fasting/starving, general malnutrition
Caloric restriction causes a decrease in the amount of sebum, due to the decrease in the synthesis of sebum constituents (lower fat intake). This leaves the skin dry/flaky as the sebum composition and production changes. This can be mitigated by consuming higher amounts of saturated fats.
How can we support our sebum production?
1) Use products and practices that preserve the skin's intentional barrier
2) Consume high quality foods like pastured meat/poultry, saturated fats, seasonal produce
3) Mitigate excessive cortisol
3) Regulate your hormones
Sources:
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Picardo M, Ottaviani M, Camera E, Mastrofrancesco A. Sebaceous gland lipids. Dermatoendocrinol. 2009 Mar;1 PMID: 20224686; PMCID: PMC2835893.
Szöllősi AG, Oláh A, Bíró T, Tóth BI. Recent advances in the endocrinology of the sebaceous gland. Dermatoendocrinol. 2018 Jan 23. PMID: 29484098; PMCID: PMC5821152.
Hoover E, Aslam S, Krishnamurthy K. Physiology, Sebaceous Glands. In:StatPearls Publishing; 2022 Jan.
Chen W, Kelly MA, Opitz-Araya X, Thomas RE, Low MJ, Cone RD. Exocrine gland dysfunction in MC5-R-deficient mice: evidence for coordinated regulation of exocrine gland function by melanocortin peptides. Cell. 1997 Dec 12. PMID: 9413988.
Saric-Bosanac S, Clark AK, Sivamani RK, Shi VY. The role of hypothalamus-pituitary-adrenal (HPA)-like axis in inflammatory pilosebaceous disorders. Dermatol Online J. 2020 Feb 15. PMID: 32239884.
Zhou, SS., Li, D., Zhou, YM. et al. The skin function: a factor of anti-metabolic syndrome. Diabetol Metab Syndr 4, 15 (2012). https://doi.org/10.1186/1758-5996-4-15
Pochi PE, Downing DT, Strauss JS. Sebaceous gland response in man to prolonged total caloric deprivation. J Invest Dermatol. 1970 Nov;55(5):303-9. doi: 10.1111/1523-1747.ep12260136. PMID: 5483834.
Ghosh S, Chaudhuri S, Jain VK, Aggarwal K. Profiling and hormonal therapy for acne in women. Indian J Dermatol. 2014 Mar;59(2):107-15. doi: 10.4103/0019-5154.127667. PMID: 24700926; PMCID: PMC3969667.