Vitamin B7 (Biotin) | Supplementopedia

Overview

Vitamin B7, known as biotin, is a water‑soluble B‑complex vitamin that serves as an essential co‑enzyme for several carboxylase enzymes. Its primary role is to facilitate the metabolism of carbohydrates, fats, and proteins, thereby supporting energy production and cellular growth.

Benefits

Energy metabolism: Enhances conversion of macronutrients into ATP, supporting basal metabolic rate.
Hair, skin, nail health: Improves keratin infrastructure, reducing brittleness and promoting growth.
Blood glucose regulation: Supports gluconeogenesis and improves insulin sensitivity in modestly deficient individuals.
Neurological support: Participates in myelin synthesis, aiding nerve conduction and cognitive function.
Pregnancy outcomes: Adequate levels reduce risk of congenital anomalies linked to folate‑biotin inter‑dependence.
Gene expression: Acts as a co‑factor for histone‑biotinylation, influencing DNA repair and epigenetic regulation.
Dermatologic conditions: May ameliorate symptoms of biotin‑responsive dermatitis and alopecia.

How It Works

Process: Biotin functions as a covalently bound co‑enzyme (biotinylation) for four mitochondrial carboxylases: pyruvate carboxylase, acetyl‑CoA carboxylase, propionyl‑CoA carboxylase, and β‑methylcrotonyl‑CoA carboxylase.
Pathway: By stabilizing carboxyl‑group transfer, it enables critical steps in gluconeogenesis, fatty-acid synthesis, and amino‑acid catabolism. Biotin also serves as a substrate for biotin‑dependent transcriptional regulators, such as histone biotinylation, which modulates chromatin structure and gene expression. In the endocrine system, biotin influences insulin signaling pathways, partly through its role in the activation of carboxylases that affect lipid and glucose homeostasis. The combined enzymatic and regulatory actions underpin its broad metabolic and cellular effects.

Dosage

Typical Dosage: Supplemental doses range from 30 µg (the adult Recommended Dietary Allowance) to 5 mg daily for therapeutic purposes.
Hair, Skin, Nail Support: 2–5 mg/day is commonly used.
Metabolic Support (Diabetics): 2–10 mg/day may be prescribed under medical supervision.
Administration: Biotin is best taken with a meal to enhance absorption, though timing is less critical than for fat-soluble nutrients.
Special Populations: Pregnant and lactating women should aim for the RDA (30 µg) unless a higher therapeutic dose is prescribed. Individuals with renal impairment may need lower doses, as excess biotin is renally excreted.

Safety & Side Effects

General Tolerance: Biotin is generally well‑tolerated.
Adverse Effects: Adverse effects are rare and usually limited to mild gastrointestinal upset or skin rash at very high intakes (>10 mg/day).
Toxicity Threshold: No established toxicity threshold exists, but doses >100 mg/day may interfere with laboratory assays (e.g., thyroid‑stimulating hormone, troponin).
Contraindications: Contraindicated in individuals with rare biotin‑idase deficiency unless under specialist supervision, as excess biotin can mask deficiency.
Drug Interactions: Potential drug interactions include anticonvulsants (which may increase biotin metabolism) and some antibiotics (e.g., streptomycin) that can impair intestinal flora‑mediated synthesis.
Special Populations: Pregnant, lactating, and pediatric populations should adhere to established recommendations unless directed by a health professional.

Chemistry

Molecular Formula: C₁₀H₁₆N₂O₃S
Molecular Weight: 244.31 g mol⁻¹
IUPAC Name: (5‑S‑(1‑oxo‑1‑methyl‑2‑pyridyl)‑1‑oxo‑1‑[3‑(1‑oxopyrrolidin‑3‑yl)‑...*).
Structure: The core structure is a fused bicyclic system comprising a ureido‑tetrahydro‑thiophene ring attached to a valeric acid chain.
Functional Groups: The key functional groups are the imidazolidone ring, the thioether bridge, and a terminal carboxyl group, which together enable covalent attachment (biotinylation) to lysine residues on target enzymes.
Solubility: Biotin is stable at pH 3–10, soluble in water (≈0.2 mg mL⁻¹ at 25 °C) and in ethanol.
Melting Point: Exhibits a melting point around 250 °C (decomposes).

Sources & Quality

Natural Sources: Naturally, biotin is abundant in egg yolk, liver, nuts (especially almonds), and certain legumes.
Commercial Production: Commercially, it is extracted from microbial fermentation (e.g., Bacillus subtilis or E. coli engineered strains) or chemically synthesized from 3‑methyl‑2‑butenyl‑1‑pyridine derivatives.
Supplement Quality: High‑grade supplements employ a purification cascade (filtration, chromatography) to achieve >99 % purity, meeting USP or EP standards.
Supplement Considerations: For supplement quality, look for “pharmaceutical‑grade” labels, certificates of analysis, and absence of heavy‑metal contaminants. Products derived from recombinant microbial cultures are generally considered safe, sustainable, and free of animal‑derived components, which is relevant for vegan or allergen‑sensitive consumers.