This article is the 12th in a series giving essential facts and figures on different vitamins.

Biotin is a sulfur-containing, B-complex vitamin found in foods and produced by microorganisms in the lower gastrointestinal tract.

Functions: Activates certain enzymes that aid in metabolism of carbon dioxide; involved in metabolism of protein, fats and carbohydrates.

Sources: Widely distributed in foods that are sources of B vitamins, including cereal-grain products, liver, egg yolk, soy flour, and yeast.

Deficiency: Signs include loss of appetite, nausea, vomiting, inflammation of the tongue, pallor, depression, hair loss, and dry, scaly skin. Some rare biotin-related inborn errors of metabolism may cause deficiency; otherwise, deficiency is extremely rare in the United States.

Excess: No effects have been reported.

Paula Kurtzweil, R..D., of FDA's Office of Public Affairs, and Theresa A. Young, of FDA's Philadelphia district office, contributed to this series.

U.S. Recommended Daily Allowances

Infants Children Adults and Pregnant or
(0-12 mo.) (1-3 years) Children 4 Years + Nursing Women

5O micrograms 150 mcg 300 mcg 300 mcg

(The U.S. RDA amounts are sufficient to meet the needs of
practically all healthy people. FDA set these based on the 1968
Recommended Dietary Allowances by the National Research Council of
the National Academy of Sciences. However, in 1989, the council
lowered its ranges of safe and adequate daily dietary intakes for
biotin to l0 to 15 micrograms for infants, 20 to 30 mcg for
children, and 30 to 100 mcg for adults. FDA is in the process of
revising its U.S. RDAs.)

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