Vitamin B12, also called cobalamin, is a cofactor involved in essential body processes such as cellular metabolism, DNA replication and red blood cell formation. Inadequate dietary B12, or poor absorption of vitamin B12 can cause a deficiency with a range of signs, symptoms and disorders. While the most notable impact of a deficiency involves the blood, gastrointestinal or nervous system, a shortfall of this vitamin can cause hair changes, including hair loss. Vitamin B12 deficiency is a serious health condition, so consult your doctor if you suspect you have a deficiency.
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Vitamin B12, Hair and DNA
Deoxyribonucleic acid, commonly known as DNA, is the information within each cell that carries the instructions for growth, development and functioning of all body cells, tissues and organs. When the cell reproduces, it must first make a copy of -- or replicate its DNA. Hair growth is dependent on synthesis of DNA and adequate vitamin B12, among other nutrients. So a potential sign of vitamin B12 deficiency is hair loss. B12 deficiency might not occur in isolation, however. If accompanied by severe protein or calorie malnutrition, iron deficiency anemia and other nutrient deficiencies, such as those caused by gastrointestinal disorders and poor digestion or absorption of nutrients, hair loss could occur as a result of a deficiency other than B12.
Despite the essential role of vitamin B12 in DNA replication and hair growth, there is little research to link a deficiency of B12 to hair loss. For example, a January 2015 study published in "World Gastroenterology Journal" studied people with inflammatory bowel disease, a condition that may lead to B12 deficiency, and found no association between a deficit of this vitamin and hair loss. A report published in the July-September 2010 issue of "Indian Journal of Dermatology" addressed that hair changes, but not necessarily hair loss, are linked to vitamin B12 deficiency. Hypopigmentation of the hair, or loss of hair color, has been reported with a deficit of B12, according to a report published in the August 1986 issue of "Archives of Dermatology."
The Anemia Link
Alopecia areata is a condition characterized by localized hair loss, or spot baldness. According to a July 2003 report in "American Family Physician," certain conditions may accompany this form of alopecia, including thyroid disorders, autoimmune conditions and pernicious anemia -- a type of anemia caused by vitamin B12 deficiency. In pernicious anemia, the intrinsic factor necessary for vitamin B12 absorption is lacking, often due to an autoimmune factor. However, the specific cause of alopecia areata is unknown, and it's unclear how common this B12 link really is. While some case reports show a link, a study of 75 people with alopecia areata, published in the March 2013 "Cutaneous and Ocular Toxicology," found no link between vitamin B12 deficiency and this form of hair loss.
While B12 deficiency can occur at any age, it's estimated that 20 percent of U.S. adults over the age of 60 are deficient in this vitamin, according to a September 2014 report in "BMJ." Particularly in the early stages, this deficiency can be difficult to diagnose because the symptoms are so diverse. Deficiency of vitamin B12 can affect a wide range of body functions, including anemia, nerve damage, depression, dementia, balance problems -- and skin and hair changes. If you think you have a B12 deficiency, see your doctor for evaluation and recommendations. Vitamin B12 deficiency can pose serious and life threatening risks to your health, so don't delay in seeking treatment.
Reviewed by: Kay Peck, MPH, RD
- National Institute of Health, Office of Dietary Supplements: Vitamin B12
- Age and Ageing: Vitamin B12 Deficiency in the Aged: A Population-Based Study
- Indian Journal of Dermatology: Diet in Dermatology: Present Perspectives
- World Gastroenterology Journal: Frequency and Associated Factors of Hair Loss Among Patients With Inflammatory Bowel Disease
- Archives of Dermatology: Reversible Hyperpigmentation of Skin and nails with white hair due to vitamin B12 deficiency.
- American Family Physician: Common Hair Loss Disorders
- Cutaneous and Ocular Toxicology: Serum Holotranscobalamine, Vitamin B12, Folic Acid and Homocysteine Levels in Alopecia Areata Patients