Vitamin B7 (Biotin)
Also known as Biotin, Vitamin H
Biotin is a cofactor for carboxylase enzymes involved in fatty acid synthesis, glucose metabolism, and amino acid breakdown. It is widely marketed for hair and nail strength, though evidence is strongest for people with true deficiency. High-dose biotin can interfere with certain lab tests.
Benefits
Strengthens brittle nails
ModerateTrials in people with brittle nails show modest improvement in thickness and reduced splitting.
Supports hair quality in deficiency
PreliminaryBiotin improves hair growth and quality when deficiency is present; evidence for healthy people is limited.
Important for energy metabolism
StrongBiotin-dependent carboxylases are required for glucose and fatty acid metabolism.
Pros & cons
Pros
- Helps brittle nails and biotin-deficiency hair loss
- Safe at standard doses
- Water-soluble with no known toxicity at RDA levels
Cons
- Overhyped for hair growth in non-deficient people
- Can interfere with blood tests at high doses
Side effects
Lab test interference
High-dose biotin can cause falsely high or low results on thyroid, troponin, and other immunoassays. Stop biotin 48–72 hours before blood tests.
Acne or breakouts
Very high doses can trigger acne-like eruptions in some users.
How to take it
Typical dose
30 mcg RDA; 2,500–5,000 mcg for nails/hair (temporary use)
Timing
Morning with food; stop 48–72 hours before blood tests
Tip: Most people do not need high-dose biotin unless a deficiency is suspected.
Forms: which one to choose
The main forms of Vitamin B7 (Biotin) compared by absorption, tolerability, and best use.
What the research says
Biotin for brittle nails
Moderate2.5 mg/day biotin improved nail thickness and reduced splitting in people with brittle nails.
How it connects
Relationships between Vitamin B7 (Biotin) and other supplements in the matrix.
Zinc and biotin are both involved in keratin and skin health; they are often combined in hair formulas.
Compare the pairingVitamin C is required for collagen synthesis, which underpins skin, hair, and nail structure alongside biotin.
Compare the pairingFrequently asked questions
What is Vitamin B7 (Biotin) used for?
Vitamin B7 (Biotin) is most commonly used for skin health, energy, and brain health. Trials in people with brittle nails show modest improvement in thickness and reduced splitting.
How much Vitamin B7 (Biotin) should I take?
A typical dose is 30 mcg RDA; 2,500–5,000 mcg for nails/hair (temporary use). Most people do not need high-dose biotin unless a deficiency is suspected. Start at the lower end and confirm the right dose for you with a healthcare professional.
When is the best time to take Vitamin B7 (Biotin)?
Recommended timing: Morning with food; stop 48–72 hours before blood tests.
What are the side effects of Vitamin B7 (Biotin)?
Reported side effects include lab test interference and acne or breakouts. High-dose biotin can cause falsely high or low results on thyroid, troponin, and other immunoassays. Stop biotin 48–72 hours before blood tests.
More Vitamins
Folate (B9)
The active B vitamin behind methylation, mood, and pregnancy health.
Vitamin B1 (Thiamine)
The energy metabolism cofactor that keeps nerves and muscles firing.
Vitamin B12 (Cobalamin)
The methylation and nerve-health vitamin that protects the brain and blood.
Compare Vitamin B7 (Biotin) with
Weighing your options? See how Vitamin B7 (Biotin) stacks up against similar supplements.