Synonyms: vitamin H, coenzyme R, vitamin B7

Characteristics: Biotin is an essential nutrient that occurs naturally in some foods and is available as a dietary supplement. This water-soluble B vitamin is a cofactor for five carboxylases that catalyze critical steps in the metabolism of fatty acids, glucose, and amino acids. It can therefore be said that it is indispensable for food processing. Biotin affects gene regulation and cell signaling. The body also needs it to produce keratin – the type of protein that makes hair, skin, and nails.

Absorption: Most biotin in food is bound to proteins, although some is also in free form. Digestive enzymes break down these bound forms of biotin, free biotin is then absorbed in the small intestine and subsequently stored in the liver.

Dietary supplements: Biotin is available in dietary supplements containing only biotin, or in a combination of B-complex vitamins and in some multivitamin/multimineral preparations. Oral free biotin is 100% absorbed, even when people consume doses up to 20 mg/day.

Natural sources: Many foods contain biotin. Foods that contain the most biotin include offal, eggs, fish, meat, seeds, nuts, and some vegetables (such as sweet potatoes). The biotin content of foods can vary, for example, plant variety and season can affect the biotin content of cereal grains, and some processing techniques (e.g. canning) can reduce the biotin content of foods. Avidin, a glycoprotein in raw egg whites, binds tightly to biotin and prevents its absorption in the gastrointestinal tract. Cooking denatures avidin so that it is unable to interfere with biotin absorption.

Effect: Biotin supplements are often promoted for hair, skin, and nail health.

Clinical effect: Clinically insufficiently verified effect of supporting hair growth. In contrast, there is more evidence for hair loss prevention (tested in biotin deficient individuals).

Recommended daily dose: adult: 30 µg for men, 30 µg for women (30 µg during pregnancy, 35 µg during breastfeeding).

Deficiency: Biotin deficiency is rare and has never been described in healthy individuals consuming a normal mixed diet. Symptoms typically appear gradually and may include hair thinning to loss of body hair, a scaly, red rash around body openings (eyes, nose, mouth, and perineum), conjunctivitis, seizures, skin infections, brittle nails, and neurological symptoms (e.g., depression , lethargy, hallucinations, and paresthesia-tingling of the limbs in adults); and hypotonia, lethargy, and developmental delay in infants. There is also a rash and an unusual distribution of fat on the face. Biotin deficiency is suffered by people with a hereditary disease - deficiency of biotinidase, an enzyme involved in biotin recycling. Furthermore, alcoholics (alcohol blocks its absorption), smokers (smoking increases its metabolism), people with malnutrition or after significant weight loss, patients with non-specific bowel disease, pregnant and lactating women, and finally consumers of raw eggs, especially egg whites. Certain medications such as antiepileptics and retinoids (treatment of acne or psoriasis) also cause a deficiency.

Interactions: High levels of biotin in the blood can affect some laboratory tests (measurement of thyroid hormones and sex hormones, vitamin D, prostate antigen, serology of infectious diseases, biomarkers of anemia and autoimmune diseases, concentration of immunosuppressants and diagnostics of heart diseases). Anticonvulsant (antiepileptic) treatment increases the catabolism of biotin, which leads to a decrease in the amount of biotin.

Adverse effects: Not observed up to a dose of 200 mg/day.

Pregnancy: safe in usual doses.

Breastfeeding: safe in usual doses.

Caution: Taking biotin without determining the cause of hair loss may prevent or delay appropriate treatment in cases where biotin deficiency is not to blame.

Toxicity: Taken as a dietary supplement, it is relatively safe and unlikely to have toxic effects because it is water soluble. Overdose may cause insomnia, excessive thirst, and urination.


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