Baker's yeast (Saccharomyces cerevisiae) is dependent on biotin for growth. Biotin is therefore added as a growth stimulant to the nutrient medium used in yeast fermentation. Also, many of the microorganisms used in modern biotechnology are biotin-dependent. Thus, biotin is added to the growth medium in such cases.

In cosmetics, biotin is used as an ingredient for hair care products.

Biotin, usually either in the form of crystalline D-biotin or brewer’s yeast, is added to many dietary supplements, infant milk formulas and baby foods, as well as various dietetic products. As a supplement, biotin is often included in combinations of the B vitamins. Monopreparations of biotin are available in some countries as oral and parenteral formulations.

Therapeutic doses of biotin for patients with a biotin deficiency range between 5 and 20 mg daily. Seborrheic dermatitis and Leiner's disease in infants respond to daily doses of 5 mg. Patients with biotinidase deficiency require life-long biotin therapy in milligram doses (5-10mg/day). Patients with HCS deficiency require supplementation of 40-100 mg/day. If biotin therapy is introduced in infancy, the prognosis for both these genetic defects are good.

A daily supplement of 60 µg biotin for adults and 20 µg for children has been recommended to maintain normal plasma levels in patients on total parenteral nutrition.

In 1998 the Food and Nutrition Board of the Institute of Medicine felt the existing scientific evidence was insufficient to calculate an EAR, and thus an RDA, for biotin. Instead an Adequate Intake level (AI) has been defined. The AI for biotin assumes that current average intakes of biotin (35 µg to 60 µg/day) are meeting the dietary requirement. An estimation of the safe and adequate daily dietary intake for biotin was made for the first time in 1980 by the Food and Nutrition Board of the United States National Research Council. The present recommendations in the USA are 20-30 µg daily for adults and children over 11 years, and 5-12 µg daily for infants and younger children. France and South Africa recommend a daily intake of up to 300 µg, and Singapore up to 400 µg biotin. Others, including the Federal Republic of Germany, assume that diet and intestinal synthesis provide sufficient amounts.

There is no direct evidence that marginal biotin deficiency causes birth defects in humans, but an adequate biotin intake/supplementation during pregnancy is advisable.

Biotin is used clinically to treat the biotin-responsive inborn errors of metabolism, holocarboxylase synthetase deficiency and biotinidase deficiency.

Large doses of biotin may be given to babies with a condition called infantile seborrhea or to patients with genetic abnormalities in biotin metabolism. A large number of reports have shown a beneficial effect of biotin in infant seborrheic dermatitis and Leiner's disease (a generalised form of seborrheic dermatitis).

Biotin supplements are sometimes given to help reduce blood sugar in diabetes patients. People with type 2 diabetes often have low levels of biotin. Some patients with diabetes may have an abnormality in the biotin-dependent enzyme pyruvate carboxylase, which can lead to dysfunction of the nervous system.

The main benefit of biotin as a dietary supplement is in strengthening hair and nails. Biotin supplements may improve thin or splitting toenails or fingernails and improve hair health. Uncomable hair syndrome in children also improves with biotin supplementation, as do certain skin disorders, such as “cradle cap”. Biotin has also been used to combat premature graying of hair, though it is likely to be useful only for those with a low biotin status. In orthomolecular medicine biotin is used to treat hair loss, but scientific evidence is not conclusive.

Biotin has been used for people in weight loss programs to help them metabolise fat more efficiently.

Human biotin deficiency is extremely rare. This is probably due to the fact that biotin is synthesised by beneficial bacteria in the human intestinal tract. Potential deficiency symptoms include anorexia, nausea, vomiting, glossitis, depression, dry scaly dermatitis, conjunctivitis and ataxia, and after long-lasting, severe biotin deficiency, loss of hair colour and hair loss (alopecia). Signs of biotin deficiency in humans have been demonstrated in volunteers consuming a biotin-deficient diet together with large amounts of raw egg white. After 3-4 weeks they developed a fine dry scaly desquamating dermatitis, frequently around the eyes, nose, and mouth. After ten weeks on the diet, they were fatigued, depressed and sleepy, with nausea and loss of appetite. Muscular pains, hyperesthesia and paresthesia occurred, without reflex changes or other objective signs of neuropathy. Volunteers also developed anaemia and hypercholesterolaemia. Liver biopsies in sudden infant death syndrome babies reveal low biotin levels. Most of the affected infants were bottle-fed.

Groups at risk of deficiency

patients maintained on total parenteral nutrition

people who eat large amounts of raw egg white

haemodialysis patients

diabetes mellitus

individuals receiving some forms of long-term anticonvulsant therapy

individuals with biotinidase deficiency or holocarboxylase synthetase (HCS) deficiency (genetic defects)

patients with malabsorption, including short-gut syndrome

pregnancy may be associated with marginal biotin deficiency

In most foodstuffs biotin is bound to proteins from which it is released in the intestine by protein hydrolysis and a specific enzyme, biotinidase. Biotin is then absorbed unchanged in the upper part of the small intestine by an electron-neutral sodium (Na+) gradient dependent carrier-mediated process and also by slow passive diffusion. The carrier is regulated by the availability of biotin, with up-regulation of the number of transporter molecules when biotin is deficient. The colon is also able to absorb biotin via an analogue transport mechanism. Once absorbed, biotin is distributed to all tissues. The presence of a specific biotin carrier protein in plasma is not yet conclusive. The liver and retinal tissues are the main storage places. Biotin metabolites are not active as vitamins and are excreted in the urine. Remarkable amounts of biotin appear in the faeces deriving from colonic bacteria.

There is very little scientific evidence to support the use of biotin in treatment of any health condition, including brittle nails and hair loss. What's more, the National Institutes of Health warns that biotin appears to be ineffective for treatment of seborrheic dermatitis.

However, some research suggests that consuming biotin in combination with chromium picolinate may be of some benefit to people with diabetes.

For instance, a 2008 study from Diabetes/Metabolism Research and Reviews found that taking a chromium picolinate/biotin combination in addition to prescription anti-diabetic medication may help improve blood sugar control in overweight or obese people with type 2 diabetes. The study involved 447 diabetes patients, each of whom was assigned to receive either chromium picolinate with biotin or a placebo for 90 days (along with their diabetes medicine). By the study's end, those who'd taken the chromium picolinate/biotin showed a significantly greater improvement in blood sugar levels (compared to members of the placebo group).

Additionally, a 2006 study from Diabetes Technology & Therapeutics found that four weeks of taking chromium picolinate with biotin (in combination with diabetes medicine) helped improve blood sugar levels in diabetes patients. Involving 43 people with poorly controlled diabetes, the study also found that the chromium picolinate/biotin supplements helped reduce cholesterol levels.

Since both of these studies tested the use of biotin in combination in chromium picolinate, it's not known whether biotin alone might produce similar results.