Vitamin B7 (Biotin): Benefits, Food Sources, Daily Needs, and Safety
What vitamin B7 (biotin) does, how much you need each day, the best food sources, deficiency signs, hair and nail claims, and supplement safety.
Key takeaways
- Biotin is vitamin B7. It is a water-soluble B vitamin involved in the metabolism of fats, glucose and amino acids.
- Most adults need 30 mcg daily. Biotin recommendations are expressed as Adequate Intake (AI), not Recommended Dietary Allowance (RDA).
- Many foods provide biotin. Liver, cooked eggs, fish, meat, sunflower seeds and some vegetables are useful sources.
- More biotin does not necessarily mean better hair or nails. Evidence for high-dose supplements in people without deficiency remains limited.
- High-dose biotin can interfere with blood tests. Certain thyroid and troponin test results may be falsely high or falsely low. Always tell your healthcare team if you take biotin supplements.
In this article
Vitamin B7, better known as biotin, is one of the eight B vitamins. Your body needs only small amounts, but biotin helps enzymes carry out reactions involved in processing fats, carbohydrates and amino acids.
Biotin is also widely promoted in supplements for hair growth, stronger nails and healthier skin. However, the fact that a deficiency can cause hair or skin problems does not mean taking large doses will provide the same benefits when your intake is already adequate.
So how much biotin do you need, which foods contain it, and what should you know before taking a supplement? This guide explains its functions, food sources, deficiency signs and an important safety issue involving laboratory tests.
What Is Vitamin B7?
Biotin, or vitamin B7, is one of the 13 essential vitamins the body needs for normal function. It belongs to the water-soluble vitamins, a group that dissolves in water rather than fat.
Biotin acts as a cofactor for five enzymes called carboxylases. These enzymes participate in reactions involving fatty acids, glucose and amino acids.[1]
Most people obtain adequate biotin from food. Although the body also recycles biotin and intestinal bacteria can produce some, the nutritional importance of bacterial production in humans remains uncertain.
What Does Biotin Do?
Biotin supports several metabolic processes, but its main role is helping particular enzymes work correctly. It does not provide calories or function as an immediate energy booster.
It Supports Nutrient Metabolism
Biotin-dependent enzymes participate in reactions involving glucose, amino acids and fats. These processes help the body use nutrients and maintain normal cellular function.
Like other B vitamins, biotin contributes to metabolism rather than directly supplying energy. Taking extra vitamin B7 does not automatically increase energy levels when nutritional needs are already met.
It Participates in Fatty Acid Metabolism
Some biotin-dependent carboxylases are involved in producing fatty acids, while others participate in pathways that process certain nutrients.
These are normal metabolic functions. They do not mean that high-dose biotin supplements increase fat burning or promote weight loss.
It Has Other Cellular Roles
Biotin also contributes to processes associated with gene regulation and cellular signaling. Researchers continue to study these functions, but they should not be confused with established benefits from taking additional biotin.[1]
How Much Biotin Do You Need?
Biotin does not have an established Recommended Dietary Allowance (RDA). Instead, nutritional recommendations use an Adequate Intake (AI), which is set when the available evidence is insufficient to calculate an RDA.
The amounts are measured in micrograms (mcg), not milligrams (mg). One milligram equals 1,000 micrograms, so the units are especially important when comparing foods with high-dose supplements.[1][2]
| Age / Life Stage | Adequate Intake (AI) |
|---|---|
| Birth–6 months | 5 mcg/day |
| 7–12 months | 6 mcg/day |
| 1–3 years | 8 mcg/day |
| 4–8 years | 12 mcg/day |
| 9–13 years | 20 mcg/day |
| 14–18 years | 25 mcg/day |
| Adults 19+ | 30 mcg/day |
| Pregnancy | 30 mcg/day |
| Breastfeeding | 35 mcg/day |
For most adults, the AI is 30 mcg daily, with the same reference value for men and women. These figures describe total nutritional intake, not a recommended supplement dose.
Some products marketed for hair or nails contain several thousand micrograms per serving. Such amounts can greatly exceed ordinary nutritional needs without necessarily providing additional benefits.
What Foods Are High in Biotin?
Biotin is found in animal and plant foods, although the amounts vary. Liver and cooked eggs are among the richer sources, while fish, meat, sunflower seeds, almonds and certain vegetables can contribute.
Biotin is only one of several B vitamins found in everyday meals. Our guide to food sources of all eight B vitamins compares their dietary sources.
Biotin content has not been measured as extensively as that of many other vitamins. The figures below are approximate and may vary by food variety, preparation and serving size.[1]
| Food | Serving | Approximate Biotin |
|---|---|---|
| Cooked beef liver | 85 g | 30.8 mcg |
| Cooked whole egg | 1 large | 10 mcg |
| Canned salmon | 85 g | 5 mcg |
| Cooked pork chop | 85 g | 3.8 mcg |
| Cooked beef | 85 g | 3.8 mcg |
| Sunflower seeds | ¼ cup | 2.6 mcg |
| Cooked sweet potato | ½ cup | 2.4 mcg |
| Roasted almonds | ¼ cup | 1.5 mcg |
| Canned tuna | 85 g | 0.6 mcg |
| Cooked spinach | ½ cup | 0.5 mcg |
| Fresh broccoli | ½ cup | 0.4 mcg |
| Cheddar cheese | 28 g | 0.4 mcg |
| 2% milk | 1 cup | 0.3 mcg |
| Plain yogurt | 1 cup | 0.2 mcg |
| Banana | ½ cup | 0.2 mcg |
For comparison, one serving of cooked beef liver provides approximately the adult AI, while one cooked egg provides about one-third of it. However, your daily intake comes from the combination of foods you eat, not necessarily from a single source.
Can Raw Eggs Affect Biotin Absorption?
Yes. Raw egg whites contain a protein called avidin, which binds to biotin and can interfere with its absorption in the digestive tract.
This concern is mainly associated with regularly consuming large quantities of raw egg whites. Cooking denatures avidin and greatly reduces its ability to bind biotin.[1]
This is a specific example of how food composition affects nutrient availability. To explore the broader process, read how vitamin absorption works.
What Happens if You Don’t Get Enough Biotin?
Biotin deficiency is rare in people who eat a varied diet. When it develops, symptoms may appear gradually and affect several body systems.[1][2]
Possible signs include thinning hair or hair loss, a red or scaly rash around the eyes, nose or mouth, conjunctivitis and brittle nails.
More severe deficiency may involve neurological symptoms such as unusual tiredness, tingling, changes in mood or, in serious cases, seizures. These symptoms are not unique to biotin deficiency and should not be used for self-diagnosis.
Who May Be at Greater Risk?
People with certain inherited conditions, chronic heavy alcohol exposure or unusual dietary circumstances may be at higher risk of inadequate biotin status. Biotin metabolism also changes during pregnancy and breastfeeding, although the clinical significance of marginal changes is still being studied.[1]
One particularly important condition is biotinidase deficiency, a rare inherited disorder that prevents the body from recycling biotin normally. It can cause serious neurological and skin problems if untreated.
Biotinidase deficiency is different from simply eating too little biotin. It is identified through medical testing, often newborn screening, and requires treatment guided by healthcare professionals.
If you experience persistent unexplained hair loss, skin changes or neurological symptoms, medical assessment is more useful than assuming that a high-dose biotin supplement will correct the problem.
Does Biotin Help Hair, Skin and Nails?
Biotin supplements are frequently advertised for faster hair growth, stronger nails and healthier skin. These claims partly come from the fact that biotin deficiency can cause problems affecting all three.
However, correcting a deficiency is not the same as taking extra biotin when your nutritional status is already adequate.
Some small studies and case reports have examined biotin supplementation for brittle nails and certain hair conditions. Many lacked comparison groups or did not establish whether participants were biotin-deficient before treatment.
According to the NIH Office of Dietary Supplements, the evidence remains insufficient to conclude that biotin supplements reliably promote hair growth or improve nails in otherwise healthy people without deficiency.[1]
Hair thinning and brittle nails may have many possible causes, including medical conditions, other nutrient deficiencies and normal changes over time. Identifying the underlying cause is more informative than assuming biotin is the missing nutrient.
Do You Need a Biotin Supplement?
Most people can obtain adequate biotin from food. Supplements may be appropriate when a specific deficiency, inherited condition or medical circumstance creates a clear need.
Our guide to when dietary supplements may be useful explains why taking extra nutrients is not automatically beneficial.
Biotin is sold as a standalone supplement, in B-complex products and multivitamins, and in formulas marketed for hair, skin and nails.
If you use a combination product, our guide to how to take B vitamins discusses supplement combinations and overlapping amounts.
No Tolerable Upper Intake Level (UL) has been established for biotin because available evidence is insufficient to identify a clear threshold for direct toxicity. However, the absence of a UL does not mean that high doses are necessary or free of risk.[1]
Can Biotin Affect Blood Test Results?
Yes. High-dose biotin can interfere with certain laboratory tests and produce misleading results. This is one of the most important practical safety concerns associated with biotin supplements.
Some laboratory tests use interactions between biotin and proteins such as streptavidin to measure substances in blood. Excess biotin from supplements can interfere with these test systems.
Depending on the test design, results may appear falsely high or falsely low. Certain thyroid hormone tests are among those that can be affected.[1][3]
The FDA has also warned about falsely low results in certain troponin tests, which are used when clinicians evaluate possible heart muscle injury, including a suspected heart attack. Such interference can delay or complicate diagnosis.[3]
Not every laboratory test is affected, and the risk depends on factors such as the amount of biotin taken, the timing of the last dose and the method used by the laboratory.
If you take biotin, particularly a high-dose hair, skin or nail supplement, tell your healthcare professional and the laboratory before testing. Our guide to reading a Supplement Facts label explains how to identify the amount of biotin in a product.
Do not assume that stopping biotin for a fixed number of hours will prevent interference with every test. If a temporary pause is needed, its timing should be determined by the healthcare professional or laboratory responsible for the analysis.
Frequently asked questions
Can You Get Enough Biotin on a Vegan Diet?
Yes. Sunflower seeds, almonds, sweet potatoes and several other plant foods contribute biotin. A varied vegan diet can provide adequate vitamin B7, although food amounts differ. Vitamin B12 is a separate concern because ordinary unfortified plant foods are not reliable sources of that vitamin.
How Long Before a Blood Test Should You Stop Biotin?
There is no single waiting period suitable for every laboratory test. The risk of interference depends on the dose, timing and test method. Tell the clinician and laboratory how much biotin you take and when you last took it. If stopping it temporarily is necessary, follow their specific instructions rather than choosing a universal 24- or 48-hour rule.
Is Biotin the Same as Collagen or Keratin?
No. Biotin is a water-soluble vitamin involved in metabolism. Collagen and keratin are structural proteins. Keratin is a major component of hair and nails, while collagen helps provide structure to skin and connective tissues. Biotin contributes to normal cellular function, but taking more does not mean the body will automatically produce more collagen or keratin.
Final thoughts
Vitamin B7 plays an essential role in nutrient metabolism, but most people need only small amounts and can obtain enough through a varied diet. Biotin deficiency is uncommon, and research does not establish that high-dose supplements improve hair, skin or nails in people whose intake is already adequate.
The most important precaution is often overlooked: supplemental biotin can interfere with certain blood tests. Knowing how much your supplement contains and telling your healthcare team before laboratory testing can help prevent misleading results.
References
- National Institutes of Health, Office of Dietary Supplements. Biotin: Fact Sheet for Health Professionals. NIH ODS.
- National Institutes of Health, Office of Dietary Supplements. Biotin: Fact Sheet for Consumers. NIH ODS.
- U.S. Food and Drug Administration. Biotin Interference with Troponin Lab Tests — Assays Subject to Biotin Interference. FDA.
- U.S. Food and Drug Administration. Testing for Biotin Interference in In Vitro Diagnostic Devices: Guidance for Industry. FDA guidance.
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