Introduction
Before its final identification as Biotin, this B-Vitamin was known as Bios IIb and Vitamin H by researchers in the first half of the twentieth century. In 1942, its chemical structure was identified, and with its synthesis the following year, Biotin was officially added to the roster of water-soluble vitamins.
Absorption and Metabolism
Significant amounts of Biotin are synthesized by bacteria in the large intestine. Nutritional Biotin is well absorbed and occurs in all the cells of the body, although in minute amounts.
Within body cells it is bound to protein, in which it serves its coenzymatic functions.
Excess Biotin is excreted in the urine. Excretion of three to six times the amount of Biotin ingested has been demonstrated; emphasizing that bacterial synthesis contributes large quantities to the body’s available supply. As such, the use of antibiotics is known to decrease the amounts of Biotin available for absorption from the intestine. Particularly oxytetracycline and the sulfonamides have been shown to produce signs and symptoms of secondary Biotin defici ency with long-term use.
The egg white protein known as avidin is known to complex with Biotin in the gut and prevent its absorption. By cooking the egg the avidin is denatured, eliminating the risk of impaired Biotin absorption. In this instance the risk of Biotin deficiency would require that a person depend solely upon raw eggs as their source of dietary protein. According to one estimate, the avidin content of more than 20 raw eggs per day for several weeks would be required to create a Biotin deficiency.
Functions
Biotin primarily serves a coenzyme role:
1. Carbon dioxide carrier in CO2-fixation reactions (carboxylation). These reactions are important for fatty acid synthesis and oxidation.
2. Deamination of certain amino acids (notably threonine, aspartic acid, serine).
Recommended Dietary Allowance (Biotin)
Clinical Deficiency
Overt deficiency is rare, but appears as:
Greyish, dry, scaly skin (especially, nose and mouth)
Loss of Appetite
Lassitude
Muscle Pain
Nausea
Extremity Paresthesia
Depression
Hair Loss
As a rule, in adults with seborrheic dermatitis treatment with Biotin alone is usually of no value. More effective treatment includes the use of all the B-vitamins required for fatty acid synthesis (Biotin, Vitamin B6, pantothenic acid, niacin, thiamin).1
Biotin Supplementation Studies (above RDA)
Brittle nails
Recent human studies have shown that Biotin supplementation (2,500 mcgs per day) can produce a 25 percent increase in the thickness of the nail plate in patients diagnosed with brittle nails of unknown cause, with up to 91 percent of patients taking this dosage experiencing improvement.2 This research is an extension of animal studies, which demonstrated that Biotin increases the strength and hardness of hooves in pigs and horses.
Infant Seborrheic Dermatitis
Biotin supplementation given to the infant or the breast-feeding mother has been shown to be effective in treatment of “cradle cap” (Seborrheic dermatitis in infants 2-12 weeks of age).3,4 (3,000 mcgs, 2X daily to mother or 100-300 mcg to infant)
Increased Insulin Sensitivity In Diabetes
Biotin supplementation enhances insulin sensitivity and increases the activity of the enzyme glucokinase in glucose metabolism. In one study, 16 mgs of Biotin per day resulted in significant lowering of fasting blood glucose in type I diabetics).5 The same has been shown in type II diabetics with a dosage of 9 mgs per day.6
Diabetic Neuropathy
High dose Biotin has been shown to improve severe diabetic nerve damage. 8 mgs, twice per day is the usual dosage.7
Biotin Toxicity
Biotin is extremely safe, and there are no reports of side effects with Biotin supplementation.8
Drug-Nutrient Interaction
1. Antibiotics
Various types of antibiotics kill off the Bifidobacterium in the large intestine that synthesize Biotin as well as other B-vitamins. Antibiotics implicated in this regard include:
Aminoglycosides
Cephalosporins
Flurosoquinolones
Macrolides
Penacillins
Sulfonamides
Tetracyclin
Trimethoprim9
2. Anticonvulsants
Anticonvulsants are reported to deplete Biotin in the body (barbiturates, primidone, carbamazepine, phenytoin).10,11,12
Standard Textbooks of Nutritional Science:
- Shils M, Shike M, Olson J, Ross C. Modern Nutrition in Health and Disease. 9th ed. Baltimore, MD: Lippincott Williams & Wilkins; 1993.
- Escott-Stump S, Mahan LK, editors. Food, Nutrition and Diet Therapy. 10th ed. Philadelphia, PA: W.B. Saunders Company; 2000.
- Bowman B, Russell RM, editors. Present Knowledge in Nutrition, 8th ed. Washington, DC:.ILSI Press; 2001.
- Kreutler PA, Czajka-Narins DM, editors. Nutrition in Perspective. 2nd ed. Upper Saddle River, NJ: Prentice Hall Inc.; 1987.
Hochman LG, Scher RK, Meyerson MS. Brittle nails: response to daily Biotin supplementation. Cutis 1993;51:303-7.
Nisenson A. Seborrheic dermatitis of infants and Leiner’s disease: a Biotin deficiency. J Ped 1957;51:537-49.
Nisenson A. Treatment of seborrheic dermatitis with Biotin and Vitamin B complex. J Ped 1972;81:630-1.
Coggeshall JC, Heggers JP, Robson MC, Baker H. Biotin status and plasma glucose in diabetics. Annals NY Acad Sci 1985;447:389-92.
Maebashi M, Makino Y, Furukawa Y, Ohinata K, Kimura S, Sato T. Therapuetic evaluation of the effect of Biotin on hyperglycemia in patients with non-insulin dependent diabetes mellitus. J Clin Biochem Nutr 1993;14:211-8.
Koutsikos D, Agroyannis B, Tzanatos-Exarchou H. Biotin for diabetic peripheral neuropathy. Biomed Pharmacothes 1990;44:511-4.
McCarty MF. High-dose Biotin, an inducer of glucokinate expression, may synergize with chromium picolinate to enable a definitive nutritional therapy for type II diabetes. Med Hypothesis 1999;52(5):401-6.
Cummings JH, Macfarland G. Role of intestinal bacteria in nutrient metabolism. J Parenter Enteral Nutr. 1997;21(6):357-65.
Krause KH, Bonjour JP, Berlit P, Kochen W. Biotin status of epileptics. Ann N Y Acad Sci 1985;447:297-313.
Said HM, Redha R, Nylander W. Biotin transport in the human intestine: inhibition by anticonvulsant drugs. Am J Clin Nutr 1989;49(1):127-31.
Mock D, Mock NI, Nelson RP, Lombard KA. Disturbances in Biotin metabolism in children undergoing long-term anticonvulsant therapy. J Pediatr Gastroenterol Nutr 1998;26(3):245-50.