vitamin
Biotin: Lab Test Warning, Food and How Much
Also known as vitamin B7, vitamin H, D-biotin, hair skin and nails vitamin
Short answer
Biotin (vitamin B7) is a B vitamin the body uses to process fats, carbohydrates and protein [1][3]. The adult Adequate Intake is 30 mcg a day, and deficiency is rare [1]. High-dose biotin can cause falsely high or falsely low lab results, including thyroid and heart tests [1][2]. Tell your doctor and the lab before blood tests.
Last reviewed · 3 sources
What is Biotin?
Biotin is a water-soluble B vitamin. It is a cofactor for five carboxylase enzymes that are key to the metabolism of fatty acids, glucose and amino acids, and it also has roles in gene regulation and cell signaling [1]. Most biotin in food is bound to protein and is freed during digestion. Most of the body's biotin is stored in the liver [1].
Forms of Biotin you'll see on labels
How much Biotin do adults need?
NIH lists these Adequate Intakes (AI) for biotin; there was not enough data to set an RDA. Reference values, not a personal recommendation.
| Group | Amount per day |
|---|---|
| Adults 19+ (men and women) | 30 mcg |
| Teens 14–18 | 25 mcg |
| Pregnancy | 30 mcg |
| Lactation | 35 mcg |
Upper limit: No UL has been set, because there is no evidence in humans that biotin is toxic at high intakes [1]. High intakes can still cause wrong lab test results [1][2].
How Biotin appears on a label
Biotin is listed in micrograms (mcg) or milligrams (mg); 1 mg equals 1,000 mcg. The Daily Value is 30 mcg for adults and children 4 and older [1]. So a 10 mg (10,000 mcg) product gives over 33,000% of the DV. Even a single 10 mg dose has interfered with thyroid function tests done within 24 hours [1].
When to take Biotin
NIH does not name a best time of day for biotin, and it does not say whether to take it with or without food. Timing matters most around lab tests: a single 10 mg dose has interfered with thyroid tests done within 24 hours [1]. Ask your doctor what to do before a blood test.
What to keep apart from Biotin
Lab tests (thyroid, troponin, other hormone tests, vitamin D)
Tests that use biotin-streptavidin technology can give falsely high or low results [1]. The FDA continues to get reports of falsely low troponin results, a heart attack test [2]. Tell your doctor and the lab you take biotin.
Anticonvulsants (carbamazepine, primidone, phenytoin, phenobarbital)
Long-term use is linked to lower biotin levels [1]. Ask your doctor or pharmacist.
Raw egg whites
Avidin in raw egg white binds biotin and blocks its absorption. Cooking makes avidin inactive [1].
Alcohol
Chronic alcohol use inhibits biotin absorption [1].
Multivitamins and B-complex
These often contain biotin too, so check your total from all products [1].
Foods that contain Biotin
- Beef liver
- Eggs (cooked)
- Salmon
- Pork
- Beef (hamburger)
- Sunflower seeds
- Sweet potato
- Almonds
Who should ask a doctor or pharmacist first
Anyone having blood tests, especially thyroid or heart (troponin) tests, should tell their doctor and the lab about biotin [1][2]. People taking anticonvulsants should discuss biotin with their provider [1]. People with biotinidase deficiency need medical care [1]. Pregnant women: at least a third develop marginal biotin deficiency despite normal intakes, and its meaning is not yet clear, so ask your provider [1].
Keep Biotin in a routine that fits
Supin schedules what you take by time of day, reminds you, and tells you when a bottle runs low.
Biotin: questions people ask
Ask your doctor. There is no set rule in these sources, but even a single 10 mg dose has interfered with thyroid tests done within 24 hours [1].
NIH says hair, skin and nail claims are supported, at best, by a few case reports and small studies. The hair reports were only in children with a rare hair disorder [1].
Beef liver, eggs, salmon, pork, beef, sunflower seeds, sweet potato and almonds are among the best sources [1].
People with biotinidase deficiency, people with chronic alcohol use, and pregnant and breastfeeding women [1].
Yes. Biotin is also called vitamin B7 [3].
Sources
- Biotin: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
- Biotin Interference with Troponin Lab Tests - Assays Subject to Biotin Interference — U.S. Food and Drug Administration
- Vitamin B — NHS
Educational information, not medical advice. The amounts above are official reference values, not a recommendation for you. Check with your doctor or pharmacist before starting or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed .