Why is biotin in vitamins? The Essential Coenzyme Explained

January 3, 2026 •

4 min read

According to the National Institutes of Health, biotin, also known as vitamin B7, is essential for metabolic processes that help your body convert food into energy. This critical function is a primary reason why is biotin in vitamins, but it's also included for its popular, though less scientifically robust, association with hair, skin, and nail health.

Quick Summary

Biotin, an essential B vitamin, is included in multivitamins because it acts as a coenzyme critical for converting macronutrients into usable energy. While often marketed for hair and nail health, its more fundamental role involves supporting key metabolic functions, neurological health, and certain stages of pregnancy.

Key Points

Metabolic Coenzyme: Biotin is a crucial coenzyme that helps your body metabolize fats, carbohydrates, and proteins into energy.
Supports Energy Production: It is involved in gluconeogenesis, the process of creating glucose from non-carb sources, and fatty acid synthesis.
Hair, Skin, and Nails: Though widely marketed for its benefits to hair, skin, and nails, evidence supporting this for healthy individuals is limited; it is most effective for those with a deficiency.
Essential for Pregnancy: Many prenatal vitamins include biotin to prevent marginal deficiency, which is common during pregnancy, and support healthy fetal development.
Potential for Lab Interference: High doses of biotin, often found in standalone supplements, can cause falsely high or low results on various lab tests, including thyroid and cardiac tests.
Deficiency is Rare: Most people get sufficient biotin from a balanced diet and from intestinal bacteria, making severe deficiency uncommon in healthy individuals.
Neurological Health: Biotin contributes to the function of the nervous system, and high doses are sometimes studied for conditions like multiple sclerosis.

The Core Metabolic Function of Biotin

Biotin, or vitamin B7, is a water-soluble B-complex vitamin that serves as a crucial coenzyme for several carboxylase enzymes in the body. These enzymes play a vital role in fundamental metabolic pathways, enabling the body to effectively process carbohydrates, fats, and proteins. This is perhaps the most critical, science-backed reason why is biotin in vitamins, ensuring these essential bodily functions proceed smoothly.

Specifically, biotin is integral to the process of gluconeogenesis, which is the synthesis of glucose from non-carbohydrate sources like amino acids. This is especially important during periods of fasting or intense exercise when the body needs alternative fuel sources. Without adequate biotin, this process would be compromised, potentially leading to issues with blood sugar regulation. Additionally, biotin is a cofactor for enzymes involved in the synthesis of fatty acids and the metabolism of branched-chain amino acids, showcasing its wide-ranging impact on the body's energy production systems.

Beyond Metabolism: The Other Roles of Biotin

While its metabolic function is scientifically proven, biotin is also included in vitamins for other, often more publicized, reasons. Many people associate biotin with cosmetic benefits, particularly for hair, skin, and nails.

Commonly Cited Benefits:

Hair and Nail Health: Biotin supports the production of keratin, the protein that forms the structure of hair and nails. For individuals with a genuine biotin deficiency (which is rare), supplementation can improve brittle nails and hair thinning. However, evidence for its effectiveness in healthy individuals is limited.
Healthy Pregnancy: Marginal biotin deficiency is surprisingly common during pregnancy due to increased metabolic demands. For this reason, many prenatal vitamins include biotin to ensure adequate levels for healthy fetal development.
Nervous System Support: Biotin plays a role in neurotransmitter activity and nerve function. Some research has explored its potential benefits for certain neurological conditions like multiple sclerosis, although more research is needed.

The Role of Biotin in Preventing Deficiency

Biotin deficiency is uncommon in the general population because the vitamin is widely available in many foods, and intestinal bacteria can synthesize it. However, certain risk factors can increase the likelihood of a deficiency, making supplemental biotin a prudent addition to multivitamins.

Risk Factors for Biotin Deficiency:

Excessive Raw Egg White Consumption: Raw egg whites contain a protein called avidin, which binds to biotin and prevents its absorption. This effect is neutralized by cooking.
Pregnancy: As mentioned, the increased metabolic rate during pregnancy can lead to marginal biotin deficiency.
Long-term Medication Use: Certain anticonvulsant drugs can impair biotin absorption or increase its metabolism in the body.
Genetic Disorders: Some rare, inherited disorders, such as biotinidase deficiency, prevent the body from properly recycling biotin.

A Comparison of Biotin Supplementation


Feature	Dietary Biotin (Food)	Biotin Supplements	High-Dose Biotin (Specific Conditions)
Primary Source	Eggs, nuts, liver, sweet potatoes, yeast	Vitamins, B-complex formulas, isolated tablets	High-dose oral tablets, sometimes in medical settings
Dosage	Adequate amounts usually met through a balanced diet (AI is 30 mcg for adults)	Varies widely, often much higher than daily needs	Ranges from 100-300 mg per day for certain neurological issues
Main Goal	Daily metabolic support	Bridging potential dietary gaps; targeting hair/skin health	Treating specific diseases (e.g., MS, rare metabolic disorders)
Effectiveness for Hair/Nails	Sufficient for healthy individuals	Limited evidence for healthy individuals; may help if deficient	Not typically necessary for cosmetic purposes
Risk of Interference with Labs	Very low	Higher, especially with high doses	Significant risk of false lab results (e.g., thyroid tests)

Potential Issues and Considerations

While biotin is water-soluble and any excess is typically excreted, high doses—especially those found in many standalone supplements—can interfere with lab tests. This can lead to misleadingly high or low results for tests related to thyroid function, cardiac health, and hormone levels. The U.S. Food and Drug Administration (FDA) has issued warnings about this issue, advising patients to inform their healthcare providers about any biotin supplementation before undergoing lab work.

Conclusion: Why Biotin Earns Its Place

In summary, biotin is in vitamins for a combination of scientifically-grounded metabolic reasons and widely marketed, but less proven, cosmetic claims. Its essential role as a coenzyme in converting food into energy is undisputed and critical for overall health. For most people, a balanced diet provides sufficient biotin, and a multivitamin acts as a form of nutritional insurance. For at-risk populations like pregnant women or those on specific medications, biotin supplementation is more directly beneficial. However, it is important for consumers to understand the distinction between biotin’s necessary metabolic function and its popular beauty-related marketing, especially considering the potential for high doses to affect medical test results. Consulting a healthcare provider is always wise to determine if biotin supplementation is truly necessary for your specific health needs.

An important consideration is the lack of robust evidence supporting high-dose biotin for hair and nail growth in healthy individuals, despite its heavy promotion for this purpose. The most significant impact is seen in those with a diagnosed deficiency. For those with underlying health conditions, such as multiple sclerosis, high doses of biotin may play a therapeutic role, but this should only be done under strict medical supervision. Ultimately, biotin is included in vitamins because it is an undeniably essential B vitamin, even if its benefits for most healthy people are more foundational than cosmetic.

Frequently Asked Questions

For individuals with a rare biotin deficiency, supplementation has been shown to improve hair and nail symptoms. However, scientific evidence is insufficient to prove that it benefits hair, skin, and nails in healthy people who already have adequate biotin levels.

Yes, biotin is widely available in many common foods, and bacteria in the gut also produce it. Most people who eat a balanced diet will get a sufficient amount of biotin without needing a supplement.

High doses of biotin can interfere with various lab tests, including those for thyroid hormones, cardiac proteins, and reproductive hormones. This can cause falsely high or low results, potentially leading to misdiagnosis. You should inform your doctor if you take a biotin supplement before any lab work.

Biotin is found in a variety of foods, including egg yolk, organ meats (like liver), nuts, seeds, and certain vegetables such as sweet potatoes and cauliflower. The avidin in raw egg whites can prevent absorption, but cooking eliminates this problem.

Biotin is water-soluble, so excess amounts are generally excreted through urine, and it has no known toxic side effects. However, the primary concern with high doses is their interference with medical lab tests, not toxicity.

Risk factors for biotin deficiency include prolonged use of certain anticonvulsant medications, excessive consumption of raw egg whites, chronic alcohol use, and rare inherited metabolic disorders. Pregnancy can also cause marginal biotin deficiency.

The inclusion of biotin in beauty supplements is largely driven by its marketing as the 'beauty vitamin' and its known link to symptoms like hair loss and skin rashes when a deficiency is present. However, this does not mean that extra biotin will provide benefits to those who are not deficient.