Biotin is an essential, water soluble B complex vitamin that aids in carbohydrate metabolism and in the formation of fatty acids. More specifically, it functions as a cofactor in four specific carboxylase reactions.

      The current RDI for biotin used by the FDA is 300 mcg. The most recent assessment for this nutrient from the National Academy of Sciences (NAS) is considerably lower, and is detailed in the table below. The Tolerable Upper Intake Level (UL) for biotin has not been established due to insufficient scientific data.

      Results of two national surveys, the National Health and Nutrition Examination Survey (NHANES III - 1988-91) and the Boston Nutritional Status Survey, do not report biotin intake. Several independent studies using earlier data (NHANES II), and actual dietary analysis have reported approximate intakes of biotin ranging from 40 to 60 mcg/day in the U.S. and Canada.

      Although widely distributed in many foodstuffs, biotin is a vitamin not widely reported in food composition tables and its availability is not well known for most foods. It is present in most foods that contain other vitamins of the B complex, and individuals who consume adequate amounts of these foods to satisfy their requirement for other B vitamins are generally getting sufficient amounts of biotin.

      Reports of biotin deficiency are fairly uncommon. It is known, however, that individuals who regularly consume raw egg white over long periods of time can develop biotin deficiency, the result of an inhibiting protein (avidin) unique to this food source. Other, less common forms of deficiency can result from intestinal malabsorption, an uncommon genetic defect (biotinidase deficiency), the use of certain anticonvulsant drugs in some individuals, and in some isolated cases, pregnancy.
      The symptoms of biotin deficiency include dermatitis (typically a red, scaly skin rash on the face), visual impairment (specifically, conjunctivitis), loss of hair (alopecia), and nervous system abnormalities (depression, lethargy, hallucinations and burning or prickling sensations in the extremities).

      Supplemental biotin is available in most broad-spectrum multivitamins, and is generally recommended to individuals who have inadequate intakes of other B complex vitamins.

      Generally, no health risks have been reported from large intakes of biotin from either dietary or supplemental sources.
      Although several studies have reported inhibition of fetal and placental growth in pregnant rats, these were the result of extremely large doses of biotin. In other studies, upwards to several thousand times the reported Adequate Intake (AI) have been administered to pregnant human females with no adverse effects to mother or child.