Biotin is a water-soluble vitamin that is generally classified as a B-complex vitamin. Biotin is required at the active site of five enzymes in the human body, collectively known as ‘carboxylases’. These carboxylases play a variety of roles in the body including, fatty acid and glucose synthesis, branched-chain amino acid metabolism, cholesterol metabolism and fatty acid metabolism.
Biotin is found in many foods, but generally in lower amounts than other water-soluble vitamins. Egg yolk, liver, and yeast are rich sources of biotin3.
Supplementation with biotin has been shown to lower plasma triglycerides and very low density lipoprotein in both type 2 diabetic subjects and non-diabetic subjects4. Similar, but more pronounced changes in triglycerides and cholesterol where found when biotin (2-5mg) was combined with chromium picolinate (600mcg) in high doses in type 2 diabetics5. Three other studies have produced similar findings6-8, including favourable changes in fasting blood glucose and HbA(1c)suggesting a synergistic mechanism between chromium picolinate and biotin. Biotin supplements might also be helpful in strengthening brittle fingernails with two trials in woman showing subjective evidence of clinical improvement9, 10.
A search of the scientific literature suggests that there are no significant negative side-effects from oral consumption of biotin in normal doses.
Biotin is typically taken in amounts between 100mcg and 1mg. However, as highlighted above, a number of studies have used between 2 and 5mg of biotin in combination with chromium picolinate to improve glucose control in type 2 diabetics. Even in these amounts, biotin is thought to have no toxicity. Individuals on long-term anticonvulsant (anti-seizure) therapy reportedly have reduced blood levels of biotin11, 12and therefore may be candidates for biotin supplementation. No specific guidelines exist concerning the timing of biotin supplementation.
Biotin typically features as part of ‘b-complex vitamin’ products or multivitamins.
As indicated above, biotin is most commonly combined with other b-complex vitamins and/or minerals.
Biotin is not known to be toxic. Oral biotin supplementation has been well-tolerated in doses up to 200,000 mcg/day in people with hereditary disorders of biotin metabolism1. In people without disorders of biotin metabolism, doses of up to 5,000 mcg/day for two years were not associated with adverse effects2.
1. Food and Nutrition Board, Institute of Medicine. Biotin. Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, D.C.: National Academy Press; 1998:374-389.