What is biotin (Vitamin B7)?

From the Guidelines

Biotin, also known as vitamin B7 or vitamin H, is a water-soluble B vitamin that plays a crucial role in metabolic processes in the human body, with recommended daily intake varying by context, such as at least 30 mg per day in enteral nutrition and 60 mg per day in parenteral nutrition, as suggested by the espen micronutrient guideline 1.

Key Points About Biotin

• It functions as a coenzyme for several carboxylase enzymes that are essential for the metabolism of carbohydrates, fats, and proteins.
• Biotin is naturally found in foods such as eggs, nuts, seeds, certain vegetables, and organ meats.
• It's particularly important for maintaining healthy hair, skin, and nails, which is why it's commonly included in beauty supplements.
• Biotin deficiency is rare but can occur in people who consume raw egg whites regularly, those with certain genetic disorders, or individuals on long-term antibiotic therapy, with symptoms including hair loss, skin rashes, brittle nails, and neurological symptoms.
• While biotin supplements are generally considered safe even at high doses, excessive intake can interfere with certain laboratory tests, particularly thyroid function tests and troponin levels, potentially leading to misdiagnosis of medical conditions.

Considerations for Specific Groups

• Breast-feeding mothers should receive an intake of at least 35 mg biotin per day orally, with additional amounts possibly needed in patients on renal replacement therapy, as per the espen micronutrient guideline 1.
• The toxicity of biotin is unlikely, with no upper limit (UL) established, and no adverse effects shown for both oral and IV administration of pharmacological doses of biotin up to 5 mg/day for prolonged periods 1.

Clinical Implications

• The recommended intake should be tailored to the individual's specific needs, such as enteral or parenteral nutrition, and other factors like pregnancy or renal replacement therapy.
• Healthcare providers should be aware of the potential for biotin to interfere with laboratory tests and consider this when interpreting results.
• Given the low risk of toxicity and the importance of biotin in metabolic processes, ensuring adequate intake is crucial for maintaining overall health and preventing deficiency.

From the Research

Definition and Role of Biotin

• Biotin, also known as Vitamin B7 or Vitamin H, is a water-soluble B-vitamin that functions as a cofactor for carboxylases, enzymes involved in cellular metabolism of fatty acids and amino acids, and in gluconeogenesis 2, 3.
• It plays an essential role in maintaining metabolic homeostasis, and its deficiency can lead to various human disorders 3, 4.

Biotin Homeostasis and Deficiency

• Biotin status in humans depends on several factors, including efficiency of enzymes involved in biotin recycling, intestinal uptake, and dietary intake 3.
• Biotin deficiency can cause symptoms such as alopecia, scaly dermatitis, seizures, hypotonia, ataxia, and mental retardation 5, 6.
• Biotinidase deficiency, an inborn error, can also lead to biotin deficiency and similar dermatologic manifestations 5, 6.

Biotin's Role in Human Metabolism

• Biotin is involved in carboxylation reactions, and its dependent carboxylases catalyze key reactions in gluconeogenesis, fatty acid metabolism, and amino acid catabolism 4.
• Biotin may also be involved in regulating transcription or protein expression of different proteins, and its deficiency can lead to non-classical biotin-deficiency manifestations in humans 4.
• Biotin is covalently attached to histones, and biotinylated histones play a role in transcriptional repression of genes and genome stability 6.