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Water-soluble vitamin

Vitamin B7

biotin

Carboxylase coenzyme for fat, carbohydrate and amino-acid metabolism; gene regulation

Essential nutrient

Reference intakes (RDA or AI) are set by the National Academies of Sciences, Engineering, and Medicine. Deficiency thresholds come from clinical and WHO guidance.

At a glance

Women, 19-50
30 mcg (AI)
Men, 19-50
30 mcg (AI)
Upper limit (adults)
Not established
How common is deficiency?
Rare

Food sources

Animal sources
Egg yolk (cooked), beef liver, salmon, pork, milk, cheese
Plant sources
Sunflower seeds, almonds, sweet potato, roasted peanuts, spinach, broccoli, whole grains

Deficiency and testing

Signs of deficiency
Thinning hair and hair loss, scaly red rash around eyes/nose/mouth, brittle nails, fatigue, depression, tingling in hands/feet
Who is at higher risk
Raw egg white excess (avidin), biotinidase deficiency (genetic), long-term parenteral nutrition, chronic anticonvulsants, pregnancy, heavy alcohol use
How it is tested
Urinary 3-hydroxyisovaleric acid (3-HIA); urinary biotin; plasma/urine organic acids; biotinidase enzyme assay (newborn screening)
Cut-offs
Elevated urinary 3-HIA indicates reduced biotin status; no universal cut-off

Symptoms are not specific. Only a clinician with the right tests can tell whether you are deficient.

Supplement forms

Common forms
D-biotin (free), biocytin in food, high-dose biotin in 'hair, skin, nails' products, prescription high-dose for specific disorders.
More effective
D-biotin in the 30-100 mcg range is enough to prevent deficiency, and oral biotin is well absorbed with or without food. High doses (up to 300 mg/day) are used only under medical supervision for biotinidase deficiency or specific neurological conditions.
Less effective
high-dose biotin (5,000-10,000 mcg) for hair/nail growth in people who are not deficient (little evidence). IMPORTANT: it can falsely alter lab results (thyroid, troponin, hormones, vitamin D), so pause before blood tests as advised by a clinician.

Safety, interactions and halal notes

Safety and interactions
Upper limit for adults: Not established. Going above the upper limit over time can cause harm, so check labels and talk to a clinician before high-dose supplements.
Halal note
The nutrient itself is not a halal question. For supplements, check the delivery form: gelatin (pork or non-halal bovine), capsule shells, glycerin, and alcohol-based carriers need halal certification. Ask for the halal certificate, not just a label claim. This is general guidance, not a certification.

Frequently asked questions

How much Vitamin B7 do adults need per day?

Women 19-50: 30 mcg (AI). Men 19-50: 30 mcg (AI). Upper limit: Not established. Needs change with age, pregnancy and health conditions.

What are the signs of Vitamin B7 deficiency?

Thinning hair and hair loss, scaly red rash around eyes/nose/mouth, brittle nails, fatigue, depression, tingling in hands/feet. These signs are not specific, so only a clinician with the right tests can confirm a deficiency.

What are the best food sources of Vitamin B7?

Animal sources: Egg yolk (cooked), beef liver, salmon, pork, milk, cheese. Plant sources: Sunflower seeds, almonds, sweet potato, roasted peanuts, spinach, broccoli, whole grains.

Which form of Vitamin B7 supplement is best?

D-biotin in the 30-100 mcg range is enough to prevent deficiency, and oral biotin is well absorbed with or without food. High doses (up to 300 mg/day) are used only under medical supervision for biotinidase deficiency or specific neurological conditions.

Sources

  1. NIH Office of Dietary Supplements fact sheet

← Back to the full nutrient guide

This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.

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