Another important member in the family of B-complex vitamins is biotin, or as it commonly referred to as, Vitamin H. Biotin functions as a coenzyme (R), which is significant in a number of metabolic processes. Coenzyme R is referred to as Carboxybiotin and is responsible for processes of carbohydrate oxidation and fatty-acid synthesis. Biotin also provides for the production of antibodies and enzymes. It is also responsible for metabolizing Vitamin B3 (niacin).
The body’s supply of biotin is primarily found in those tissues that provide for metabolic activities. Bacteria in our small intestines also produce varying amounts of biotin. However, because biotin is not readily absorbed, this bacterial source is not reliable for adequate dietary needs. Because Vitamin H is water soluble, it must be obtained from external dietary sources.
Of particular interest are glycoproteins, which are formed from a sugar and protein molecule. There is a specific glycoprotein named Avidin, which dramatically diminishes our abilities to absorb biotin for use in our systems. This would only be of major concern if our dietary intake of raw egg whites exceeded six per day. Therefore, deficiencies of Vitamin H are very unlikely to occur.
|Food||Serving Size||K Cals||Amount (mcg)||% DV|
|Chard, Boiled||1 cup||35.0||10.50||35.0|
|Tomato, Red, Raw, Ripe||1 cup||37.8||7.20||24.0|
|Lettuce, Romaine||2 cup||15.7||2.13||7.1|
|Peanuts, Raw||0.25 cup||207.0||26.28||87.6|
|Carrots, Raw||1 cup||52.5||6.10||20.3|
|Egg, Hen, Whole, Boiled||1 each||68.2||7.04||23.5|
|Onions, Raw||1 cup||60.8||5.60||18.7|
|Cabbage, Raw||1 cup||22.3||1.78||5.9|
|Cucumber, Raw||1 cup||13.5||0.94||3.1|
|Cauliflower, Raw||1 cup||25.0||1.50||5.0|
|Milk, Goat||1 cup||167.9||8.54||28.5|
|Yogurt, Cow Milk, Low Fat||1 cup||155.1||7.35||24.5|
|Sweet Potato, Peeled After Baking||1 cup||206.0||8.60||28.7|
|Milk, Cow, 2%||1 cup||121.2||4.88||16.3|
|Raspberries, Fresh||1 cup||60.3||2.34||7.8|
|Strawberries, Fresh||1 cup||43.2||1.58||5.3|
|Halibut, Baked/Broiled||4 oz-wt||158.8||5.67||18.9|
|Nuts, Walnuts||0.25 cup||163.5||4.75||15.8|
|Green Snap/String Beans, Boiled||1 cup||43.8||1.00||3.3|
|Nuts, Cashews, Raw||0.25 cup||196.6||4.45||14.8|
|Avocado, All Varieties||1 cup||235.1||5.26||17.5|
The most popular use for the dietary supplementation of biotin is within its application for hair and nail problems. Biotin has been clinically researched to prevent the complete or partial loss of hair (known as alopecia), and to assist in the health of hair in both children and adults.  It may also support the overall health of finger and toenails that are thin, brittle, and/or splitting. 
Lower levels of Vitamin H are often times associated with certain chronic illnesses. Diabetes is a particular area of concern with the dietary supplementation of biotin. Biotin may help to improve blood sugar levels in adults suffering from type II diabetes (non-insulin dependent diabetes mellitus), and may even synthesize and foster the release of insulin in our body. [3, 4] Complications in persons that suffer long term diabetes conditions may also benefit by biotin supplementation.
Studies have suggested that biotin supplementation can improve conditions associated with peripheral neuropathy in as little as one month.  Peripheral neuropathy is defined as damage to the nerves in the body’s extremities. Symptoms of peripheral neuropathy include; numbness, tingling, muscle weakness, and burning sensations. These reactions typically manifest in the calf and foot regions of the lower extremities.
There have also been many areas of research concerning dietary biotin availability in infants and children. Deficiencies have been attributed to numerous conditions in this demographic. Infants who are deficient in this B-vitamin often develop a scaly scalp condition know as “Cradle Cap” (seborrheic dermatitis).  Seborrheic dermatitis is also seen in conjunction with eczema in children who suffer from the inability to break down the amino acid phenylalanine.  This disorder is referred to as phenyulketonuria, or PKU. Of greatest importance in regards to infant supplementation of biotin, may be its association with Sudden Infant Death Syndrome. SIDS may be directly linked to an underlying dietary deficiency of biotin.  More research is necessary to further support this preliminary study.
Estimated safe and adequate dietary intake values for biotin (established in 1998) expressed in micrograms :
|30 micrograms/day||30 micrograms/day||35 micrograms/day||35 micrograms/day|
Again, biotin deficiencies are very uncommon in humans. Those individuals who are currently on long-term therapy with anticonvulsants or anti-biotic medications may be especially at risk. Initial symptoms of a biotin deficiency may be similar to other B-vitamin deficiencies. Initial signs and symptoms may include;
- neural disorders
- muscular disorders
Severe deficiencies may be directly associated with the thinning and loss of hair color, or the eventual complete loss of hair. Other signs of an extreme deficiency include; 
- scaly skin
- body rashes
- abnormalities of the central nervous system
In clinical settings, deficiencies in humans have been observed in persons receiving parenteral nutrition for extended periods of time.  Parenteral nutrition is the receiving of nutrients intravenously, rather than through normal intake via the mouth or stomach
Toxicities of biotin have never been reported in humans. Overdoses of the vitamin may, however, cause the malabsorption of other nutrients, particularly B-compound vitamins.
1. Camacho FM, Garcia-Hernandez MJ. Zinc aspartate, biotin, and clobetasol propionate in the treatment of alopecia areata in childhood. Pediatr Dermatol. 199;16(4): 336-338.
2. Houchman LG, et al. Brittle nails: response to biotin supplementation. Cutis. 1993;51: 303-307.
3. McCarthy MF. Toward practical prevention of type 2 diabetes. Med Hypotheses. 2000;54(5): 786-793.
4. Maebashi Y. et al. Therapeutic evaluation of the effect of biotin on hyperglycemia in patients with non-insulin dependent diabetes mellitus. J Clin Biochem Nutr. 1993 May; 14(3): 211-218.
5. Koutsikos D, Agroyannis B, Tzanatos-Exarchou H. Biotin for diabetic peripheral neuropathy. Biomed Pharmacother. 1990;44: 511-514.
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8. Johnson AR, et al. Biotin and Sudden Infant Death Syndrome. Nature. May 1980;285(5761): 159-60.
9. Strom CM, Levine EM. Chronic vaginal candidasis responsive to biotin therapy in a carrier of biotinidase deficiency. Obstet Gynecol. 1998;92(4 Pt 2):644-646.
10. Marshall MW, Kliman PG, Washington VA, Mackin JF, Weinland BT. Effects of biotin on lipids and other constituents of plasma of health men and women. Artery. 1980;7(4):330-351.
11. Committee on the Scientific Evaluation of Dietary Reference Intakes, Institute of Medicine. (1998) Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic acid, Biotin, and Choline. National Academy Press, Washington, DC.
12. Mock DM. Skin manifestations of biotin deficiency. Semin Dermatol. 1991; 10 (4): 296-302.
13. Forbes GM, Forbes A. Micronutrient status in patients receiving home parenteral nutrition. Nutrition. 1997;13(11-12):941-944