Vitamin B7, also called biotin, vitamin H or vitamin B8, is a colorless, water-soluble member of the B vitamin group. There are eight different forms of biotin, but only one of them – D-biotin – occurs naturally and has full vitamin activity. Biotin can only be synthesized by bacteria, molds, yeasts, algae, and by certain plant species.
A sufficient intake of vitamin B7 (biotin) is important as it helps the body to convert food into glucose, which is used to produce energy produce fatty acids and amino acids (the building blocks of protein) activate protein/amino acid metabolism in the hair roots and fingernail cells. The European Food Safety Authority (EFSA), which provides scientific advice to assist policy makers, has confirmed that clear health benefits have been established for the dietary intake of biotin (vitamin B7) in contributing to: normal macronutrient metabolism; normal energy yielding metabolism; the maintenance of normal skin and mucous membranes; the normal function of the nervous system; the maintenance of normal hair; normal psychological functions.
Although there is no direct evidence that marginal biotin deficiency causes birth defects in humans, an adequate biotin intake/supplementation during pregnancy is advisable.
Vitamin B7 deficiency is extremely rare, which is probably due to the fact that biotin is synthesized by beneficial bacteria in the human digestive tract. Groups at risk of biotin deficiency include patients maintained on total intravenous nutrition, hemodialysis patients, diabetes mellitus patients, and patients with an impaired uptake of vitamins from food. In addition, pregnancy may be associated with marginal biotin deficiency. Symptoms include hair loss, dry scaly skin, cracking in the corners of the mouth, swollen and painful tongue, dry eyes, loss of appetite, fatigue, insomnia, and depression.
The richest sources of vitamin B7 (biotin) are yeast, liver and kidney. Egg yolk, soybeans, nuts and cereals are also good sources. 100 g liver contains approximately 100 micrograms (mcg) biotin, whereas most other meats, vegetables and fruits only contain approximately 1 mcg biotin /100 g.