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Biotin or Vitamin H

Biotin is also known as vitamin H, biocytin, or biotinyllysine. It functions primarily as a coenzyme in protein, fat, and carbohydrate metabolism. To be active within a cell, biotin must react within a magnesium framework requiring ATP to form biotinyl 5'-adenylate. Biotinyl 5'-adenylate is also known as activated biotin. One of the predominant enzymes requiring biotin is carboxylase. Examples of biotin-dependent enzymes include acetyl CoA carboxylase, pyruvate carboxylase, propionyl CoA carboxylase, and ß-methylcrotonyl CoA carboxylase. These enzymes are needed for energy production (carbohydrate, protein, and fatty acid metabolism) as well as the catabolism of certain proteins .

Sources

Biotin is widely distributed in foods. The best sources include liver, soybeans, egg yolk, cereal, legumes, and nuts. Biotin is also synthesized by bacteria within the colon. Avidin, a protein found in raw egg whites, can bind to biotin (found in the yolk) and prevent biotin absorption. Besides Escherichia coli, this is sufficient reason to refrain from raw whole egg consumption.

Governmental Recommended Intake

In general, the RDI of biotin is 30 to 100 µg/day. The colon does not synthesize enough biotin to meet one's daily needs.

Deficiency symptoms

Biotin deficiency is characterized by symptoms that may include

• Depression

• Hallucinations

• Muscle pain

• Localized paresthesia

• Anorexia

• Nausea

• Alopecia

• Scaly dermatitis

Impaired biotin ingestion can cause deficiency. Impaired biotin absorption may be caused by the ingestion of raw eggs, various gastrointestinal disorders, or the use of anticonvulsant medications. Alcoholism also can lead to biotin deficiency.

Human Studies

No exercise, training for biotin supplementation studies have been done to date on this nutrient as a single compound.