Seborrheic dermatitis is a skin condition characterized by occasional dandruff that can accumulate into yellow, greasy scales that may or may not itch. The condition, as designated by its name, affects the sebaceous glands or sebum-producing cells of the body. These glands are the most densely organized on the face, scalp and trunk, according to the Online Merck Manual. Seborrheic dermatitis can occur in childhood or adulthood and can be affected by other chronic disease states.
Skin Yeast
The family of skin yeast known as the Malassezia species are implicated in the onset and progression of seborrheic dermatitis. A 2006 American Academy of Dermatology article notes that the skin fungus uses the natural fatty acids found in the sebum, or oil, of the skin to further their development and reproductive processes. As the yeasts use the sebum to grow and breed, the byproducts accumulate and become irritating to the skin causing the seborrheic dermatitis. Many yeasts or fungus cohabitate at low levels in the body or along the skin surface, but when the immune system is compromised, these organisms become opportunistic and can grow wildly. By overwhelming the immune system, the Merck Manual notes that stress, fatigue and AIDs can increase the risks for developing seborrheic dermatitis.
Altered Fatty Acid Metabolism
Fatty acids are the fundamental unit of fat digestion. The majority of fatty acid units are taken into the body in the form of triglycerides. They are absorbed through the intestinal membrane to perform a variety functions, including forming the lubricating substance of our skin--sebum. The 2006 "American Academy of Dermatology" article notes that the Malassezia fungus alters the fatty acids of the skin. They thrive off saturated fatty acids, so when they cleave or remove them from the sebum, they leave the remaining unsaturated fatty acids to accumulate. The unsaturated fatty acids have a non-uniformed structure, which causes them to penetrate the barrier of the skin and lead to inflammation. Inflammation amongst the accumulating unsaturated fatty acids paints the picture of seborrheic dermatitis.
Neurological Conditions
Seborrheic dermatitis has often been associated with chronic degenerative neurological diseases such as Parkinson's disease and amylotropic lateral sclerosis (ALS). The disease is found more commonly and in more severe forms in people with these diseases. Additionally, these conditions give rise to a more dense variety of the disease, concentrated more locally to the trunk and extremities versus the scalp and face. A 2000 "American Family Physician" journal article postulates that seborrheic dermatitis occurs in this population of people due to their chronically immobile state. Sebum is believed to abnormally accumulate under these conditions, instead of moving around and being expressed from the body. The fungus resultantly has a pool of fatty metabolites from which to consume.
Biotin Deficiency
When seborrheic dermatitis occurs in newborns and small children, it is often termed cradle cap. Cradle cap, according to naturopathic doctor and author of "The Clinician's Handbook of Natural Medicine," Joseph E. Pizzorno Jr., evolves from an underlying deficiency in biotin. Biotin is a B-vitamin that can be consumed from the diet, but also sources from the friendly bacteria of the large intestines. Pizzorno notes that in children, an imbalance in friendly bacteria also known as dysbiosis, can lead to a biotin deficiency. In adults, he notes specifically that biotin supplementation alone will not be enough and that the fatty acid metabolism must be addressed in concert.
References
- The Merck Manuals: Seborrheic Dermatitis
- American Academy of Dermatology: "Role of Lipid Metabolism in Seborrheic Dermatitis (Dandruff)"
- "American Family Physician": Treatment of Seborrheic Dermatitis
- "The Clinician's Handbook of Natural Medicine"; Joseph E. Pizzorno, Jr; 2002
