Biotin deficiency | |
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Biotin | |
Specialty | Endocrinology |
Biotin deficiency is a nutritional disorder which can become serious, even fatal, if allowed to progress untreated. It can occur in people of any age, ancestry, or of either sex. Biotin is part of the B vitamin family. Biotin deficiency rarely occurs among healthy people because the daily requirement of biotin is low, many foods provide adequate amounts of it, intestinal bacteria synthesize small amounts of it, and the body effectively scavenges and recycles it in the kidneys during production of urine.
Genetic disorders such as multiple carboxylase deficiency (MCD) (which includes biotinidase deficiency and holocarboxylase synthetase deficiency)[1] can also lead to inborn or late-onset forms of biotin deficiency.[2] In all cases – dietary, genetic, or otherwise – supplementation with biotin is the primary (and usually only)[3] method of treatment.[1][4] The prognosis for congenital MCD is good if biotin supplementation is begun quickly after birth and carried on throughout the patients life.[5]
The average dietary intake of biotin ranges between 35 and 70 micrograms/day in the western population.[2]
Biotin is a coenzyme for five carboxylases in the human body (propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, pyruvate carboxylase, and 2 forms of acetyl-CoA carboxylase.) Therefore, biotin is essential for amino acid catabolism, gluconeogenesis, and fatty acid metabolism. Biotin is also necessary for gene stability because it is covalently attached to histones. Biotinylated histones play a role in repression of transposable elements and some genes. Normally, the amount of biotin in the body is regulated by dietary intake, biotin transporters (monocarboxylate transporter 1 and sodium-dependent multivitamin transporter), peptidyl hydrolase biotinidase (BTD), and the protein ligase holocarboxylase synthetase. When any of these regulatory factors are inhibited, biotin deficiency could occur.[23]
The only reliable method for determining biotin deficiency is the abundance of biotinylated 3-methylcrotonyl-CoA carboxylase and propionyl-CoA carboxylase in lymphocytes. The level of biotin in urine can be used to identify biotin-supplemented individuals, and the level of 3-hydroxyisovaleric acid in urine can (unreliably) detect biotin-deficient patients.[24]
In the United States, biotin supplements are readily available without a prescription[25] in amounts ranging from 300 to 10,000 micrograms.[26] 30 micrograms daily is identified as Adequate Intake for men and women 19 years and older. 35 micrograms daily is required for lactating women.[27]
Most healthy individuals meet these recommended intakes, however many still take up to 500 to 1,000 micrograms of biotin daily.[28]
Deficiency is rare[2] in locations where egg-white enriched or ketogenic diets are common.[29] Pregnancy, however, alters biomarkers of biotin[30] and despite a regular biotin intake, approximately half of the pregnant women in the U.S. are marginally biotin deficient.[14]