Biotin (Vitamin B7): What It Does and When You Might Need It
Biotin, also called vitamin B7, is a tiny but important nutrient your body uses to turn food into energy and to keep skin, hair, and nails healthy. Most people get enough from food and gut bacteria, but a few situations — pregnancy, certain medications, or medical issues — can lower your levels. Before you grab a high-dose supplement, know what biotin really does and where it can cause trouble.
Benefits, food sources, and who may need more
Biotin helps with metabolism of carbs, fats, and proteins. People often take it hoping for stronger hair and nails. If you’re actually deficient, supplements can help. But if your levels are normal, mega-doses probably won’t make a visible difference.
Good food sources: cooked eggs, liver, nuts, seeds, legumes, and some whole grains. Raw egg whites contain avidin, a protein that binds biotin and can cause deficiency if you eat lots of raw eggs — cooking destroys avidin. The Adequate Intake for most adults is about 30 mcg/day (pregnancy similar, lactation slightly higher).
Who might need supplements: people with inherited biotinidase deficiency, those on long-term broad-spectrum antibiotics, people taking some anti-seizure drugs (like carbamazepine or phenobarbital), people on prolonged total parenteral nutrition, and anyone with certain gut disorders that impair absorption.
Dosage, safety, and important warnings
Typical supplements range from 1,000 mcg to 10,000 mcg (1–10 mg) — much higher than the daily intake recommendation. There’s no official upper limit, and biotin is water-soluble, so excess is usually excreted. Still, high doses can cause acne, stomach upset, or other mild issues.
A critical safety point: biotin can interfere with many lab tests. High biotin levels may cause falsely low or high results for thyroid tests, troponin (a heart attack marker), hormone tests, and more. If you’re having important blood work, tell your provider and stop high-dose biotin 48–72 hours before testing when possible.
If you’re thinking about supplements: pick a reputable brand, check the label, and don’t assume more is better. Talk to your doctor if you’re pregnant, breastfeeding, on prescription meds, or have a medical condition. They can check whether you really need biotin and advise on dose and timing before blood tests.
Quick takeaway: biotin matters, but deficiency is uncommon. Eat a balanced diet, avoid large amounts of raw egg whites, and be cautious with high-dose supplements — especially before lab work or if you’re on certain medications.
