Biotin, also known as vitamin H or vitamin B7, belongs to the group of B-complex water-soluble vitamins. The body produces only a small amount of biotin, so most of the biotin we need must come from food. Biotin is involved in the conversion of carbohydrates, fats, and protein into usable energy for the body.
Biotin joins with protein enzymes to regulate the breakdown of foods in the body and convert them to energy. Some researchers believe that biotin also plays a role in the duplication and “reading” (replication and transcription) of deoxyribonucleic acid (DNA).
Makers of dietary supplements promote biotin to treat brittle fingernails, dry skin, and hair loss. It is sold as a dietary supplement in capsules or tablets, either alone, in a multivitamin, or combined with brewer's yeast. Biotin is also added to cosmetics and skin creams. In animal studies, biotin has improved the condition of horse hooves, but no controlled studies have shown the same effect on human fingernails. Biotin deficiency does cause hair loss, but there is no proof that supplemental biotin prevents hair loss.
Biotin is one of the less familiar B vitamins. It was discovered in the 1930s by researchers experimenting with different diets for chickens and rats, and later it was discovered to be essential to human health. Bacteria, yeasts, mold, algae, and some plants make biotin. The large intestine (colon) in humans contains some bacteria that synthesize biotin. Researchers believe that a portion of this biotin is absorbed into the bloodstream, but they are uncertain how much or how available it is to the body.
Adequate intake (mcg/day)
Children 0-6 mos.
Children 7-12 mos.
Children 1-3 yrs.
Children 4-8 yrs.
Children 9-13 yrs.
Children 14-18 yrs.
Adults 19≥ yrs.
mcg = microgram
SOURCE: Office of Dietary Supplements. “Biotin: Fact Sheet for Health Professionals.” National Institutes of Health. https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional (accessed April 13, 2018).
Biotin is essential to life. It combines with four different enzymes that control different metabolic reactions related to energy production and the building of new molecules from simple nutrients. Biotin helps the body:
Some researchers believe that biotin binds to proteins called histones, which open up chromosomes so that their DNA becomes accessible and can be copied. If this is true, biotin could play a role in gene expression.
The Institute of Medicine (IOM) of the National Academy of Sciences has developed values called dietary reference intakes (DRIs) for vitamins and minerals. The DRIs consist of three sets of numbers: recommended dietary allowance (RDA), adequate intake (AI), and tolerable upper intake level (UL). RDAs define the average daily amount of the nutrient needed to meet the health needs of 97%–98% of the population. AIs are estimates set when there is not enough information to determine an RDA. The UL is the average maximum amount that can be taken daily without risking negative side effects. DRIs are calculated for children, adults, and pregnant and breastfeeding women.
The IOM has not set RDA values for biotin because of incomplete scientific information. Instead, there are AI levels for all age groups. AI levels for biotin are measured by weight (micrograms or mcg). No UL levels have been set due to a lack of data.
The AIs for biotin for healthy individuals are:
Biotin is found in small quantities in many foods. Bacteria in the large intestine also make biotin. Unlike some vitamins, biotin is recycled and reused by the body, meaning that daily intake does not need to be high. Only small amounts of biotin are lost in urine. Biotin in food is stable and minimally affected by heat, light, or air.
The approximate biotin content in some common foods is:
Biotin deficiency is very rare worldwide. Only a few conditions are known to cause biotin deficiency. Two rare inherited genetic disorders cause the body to need excessive amounts of biotin. These disorders are treated with high-dose biotin supplements. Prolonged (months or years) consumption of raw egg whites can also cause a deficiency. A protein in raw egg whites binds biotin and makes it unavailable to the body. Cooking the egg releases the biotin. Receiving all nutrition through intravenous feeding (total parenteral nutrition or TPN) for an extended period may also lead to a shortage of biotin in the body.
Symptoms of biotin deficiency include skin and hair problems, such as a red, scaly rash on the face, increased susceptibility to fungal infections, brittle hair, and hair loss. Individuals may also develop seizures, problems with coordination, and muscle cramps. Biotin deficiency has not been known to cause death. These symptoms have many other causes that should be considered first, however, because biotin deficiency is so rare.
In many species, pregnant animals who are biotin deficient give birth to offspring with birth defects at a higher rate than animals who have adequate levels of biotin. The same effect has not been seen in humans, but blood levels of biotin tend to drop in pregnant women, causing concern among researchers that pregnant women may develop marginal biotin deficiencies with no visible symptoms. Dietary supplements of biotin are not routinely recommended for women who are pregnant, but these women should make a special effort to obtain the adequate intake of 30 mcg biotin daily through diet. Pregnant and breastfeeding women should not take a biotin dietary supplement unless directed by their healthcare provider.
Biotin is known to interact with a few drugs and dietary supplements:
No complications are expected from biotin. Even when large doses are taken for long periods, there are no reported side effects.
Biotin deficiency is rare, so as long as children are eating a well-balanced diet, parents should have almost no concern about their children's biotin needs being met.
See also Atkins diet ; Carbohydrates ; Dietary reference intakes (DRIs) ; Dietary supplements ; Fats ; Minerals ; Protein ; Vitamins .
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