Biotin, a fairly recently named B vitamin, was discovered by the deficiency symptoms created through consuming large amounts (about 30 percent of the diet) of raw eggs. Avidin, a protein and carbohydrate molecule in the egg white, binds with biotin in the stomach and decreases its absorption. Cooking destroys the avidin, so the only concern about this interaction is with raw egg consumption. Otherwise, biotin is one of the most stable of the B vitamins.
Sources: Many foods contain biotin, but most have only trace amounts. It is hard to obtain enough biotin from the diet. Luckily, our friendly intestinal bacteria (lactobacillin) produce biotin. This vitamin is found in egg yolks, liver, brewer’s yeast, unpolished rice, nuts, and milk.
Functions: The biotin coenzymes participate in the metabolism of fat. Biotin is needed for fat production and in the synthesis of fatty acids. It also helps incorporate amino acids into protein and facilitates the synthesis of the pyrimidines, part of nucleic acids, and therefore helps the formation of DNA and RNA.
Uses: A common use of biotin is to help normalize fat metabolism and utilization in weight-reduction programs, and to help reduce blood sugar in diabetic patients, with a dosage of between 200–400 mcg. per day. Biotin has also been in wide use to prevent or slow the progression of graying hair or baldness. This may work, however, only when these symptoms are related to biotin deficiency; although, because of the nutrient and protein support of biotin, it may indeed have some hair-stimulating effect.
Biotin is often used for problems such as dermatitis or eczema, especially in infants, most often with appropriate intake of other B vitamins, such as riboflavin, niacin, and pyridoxine and vitamin A. It has also been used to treat muscle pains, though skin and hair are the main focus of supplementation. More recently, biotin has been used for diabetics and those with an overgrowth of intestinal yeast.
Deficiency and toxicity: There is no known toxicity with biotin, even in high amounts. Excesses are easily eliminated in the urine. Deficiency symptoms are also uncommon. Unless we are on a raw-egg diet or have taken a lot of antibiotics, especially sulfa, which diminish our biotin-producing intestinal bacteria, we are usually secure against biotin deficiency.
The raw-egg study generated symptoms such as fatigue, nausea, loss of appetite, muscle pains, and depression. Other symptoms that have since been seen with biotin deficiency include dry and flaky skin, loss of energy, insomnia, increases in cholesterol, sensitivity to touch, inflamed eyes, hair loss, muscle weakness, and impaired fat metabolism. Several enzymes depend on biotin to function properly. Without them, we cannot utilize our foods as well.
Biotin deficiency is sometimes seen in babies when a biotin-deficient formula is used or there is some problem with intestinal biotin synthesis. If this occurs, hair loss, muscle weakness, irritated eyes, and a scaly rash may result. In some studies in juveniles, biotin deficiency was seen to result in hair loss and occasional balding. With more advanced biotin deficiency in people of all ages, elevation in cholesterol, anemia, or changes in the electrocardiogram may occur.
Requirements: The recommended level of biotin needed in the diet ranges from 150–300 mcg., depending on how well it is produced by the intestinal bacterial flora. Probably 300–400 mcg. is a safer range. We need extra biotin if we consume raw eggs or have used antibiotics, especially the sulfa drugs. Biotin requirements are also higher during pregnancy and lactation. Infants require at least 50 mcg. per day. The need rises to an RDA of 120 mcg. at ages 7–10; after age 11, it is over 200 mcg. A common amount of biotin in vitamin B supplements is 400 mcg.