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Vitamin B7 (Biotin)

Vitamin B7 (Biotin) Functions

Vitamin B7 is a water soluble vitamin, an essential nutrient involved in metabolism of fatty acids, amino acids and glucose (gluconeogenesis) [1].

The other name for vitamin B7–biotin–originates from the Greek biote, which means life.

Vitamin B7 was formerly known as vitamin H.

Recommended Daily Intake

According to Institute Of Medicine in the US, the Adequate Intake (AI) for biotin for adults is 30 micrograms/day, including during pregnancy, and 35 micrograms/day during breastfeeding [1].

Food Sources of Biotin

Examples of foods rich in biotin [1,2]:

  • PLANT FOODS: peanuts, almonds, sunflower seeds, walnuts, pecans, sweet potatoes, strawberries, mushrooms, broccoli, avocado, spinach, carrots
  • ANIMAL FOODS: liver, eggs (mainly yolks), fish (salmon), pork
  • OTHER: baker’s yeast

Normal intestinal bacteria synthesize biotin, but it is not known if it is absorbed [1].

Biotin Absorption

Biotin can be absorbed in both small and large intestine [4].

Biotin Deficiency: Causes, Symptoms

Biotin deficiency, which is rare, may be caused by [1,3]:

  • Starvation, rapid weight loss
  • Eating raw egg whites, which contain the protein avidin, which binds biotin and prevents its absorption. In cooked eggs, avidin is denaturated and thus unable to bind biotin.
  • Prolonged treatment with certain anticonvulsant drugs (phenytoin, primidone, and carbamazepine) or antibiotics [3]

Symptoms. Within 3-5 weeks after the onset of low biotin intake, hair loss, red, scaly rash on the face and genitalia (seborrheic dermatitis) and fungal infections can appear; in infants, yellow crusts on the scalp (cradle cap) can appear. After a month or so, nausea, vomiting, tingling in arms and legs, depression and hallucinations can appear [1,3].

Biotinidase Deficiency

Biotinidase deficiency is a rare hereditary disorder with a lack of the enzyme biotinidaze, which results in reduced absorption of biotin. Symptoms, which usually appear in the first six months of life and can be triggered by an illness or starvation, may include patchy hair loss (alopecia), facial rash, seizures, breathing and swallowing difficulties, vision or hearing loss and failure to thrive. With treatment, patients may run a normal lifestyle and have an excellent prognosis [5].

Diagnosis is made by a blood test. Treatment is by oral biotin supplements.

Biotin Supplements

Without prescription (over-the-counter):

  • D-biotin in the form of tablets

By prescription:

  • D-biotin by intramuscular or intravenous injection.

Possible Biotin Supplements Benefits

Biotin supplements are EFFECTIVE for:

  • Prevention and treatment of biotin deficiency, including deficiency that can occur in patients on kidney dialysis [6]

Biotin is POSSIBLY INEFFECTIVE or there is INSUFFICIENT EVIDENCE about its effectiveness in prevention or treatment of seborrheic dermatitis including Leiner’s disease in infants, acne, hair loss, brittle nails, diabetes or diabetic nerve pain [1,6].

Biotin Safety: Side Effects, Toxicity

Biotin, even in high doses, is not known to be toxic and no significant side effects have been observed [1,7].

Pregnancy category for biotin has not been determined. If you intend to use biotin during pregnancy or breastfeeding, speak with your doctor.

Biotin Interaction With Drugs

  • Anticonvulsants primidone, carbamazepine, phenobarbital, phenytoin and carbamazepine may reduce biotin activity [1].
  • Pantothenic acid (vitamin B5) supplements in large doses may decrease biotin absorption [1].

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