Biotin (also called vitamin B7 or vitamin H) is a water-soluble B-complex vitamin that acts as an enzymatic cofactor of the five human carboxylases, key enzymes in the metabolism of carbohydrates, fats and amino acids. It contributes to normal energy-yielding metabolism, to the normal functioning of the nervous system, to the maintenance of normal hair, to the maintenance of normal skin and to 3 further physiological functions officially authorized at European level. This page covers how it works, its food sources, the studied doses, the commercial forms and where it fits within the Pleniage portfolio.
What is biotin?
Biotin is a water-soluble B-complex vitamin, also known as vitamin B7 or, in older European literature, vitamin H (from Haar und Haut, "hair and skin" in German, after the early observations of its role in skin health). It is an organic sulfur-containing compound that the body cannot synthesize in sufficient amounts and must obtain through the diet. A small part of the biotin available to the body also comes from synthesis by the gut microbiota in the colon, although the quantitative contribution of this source remains under investigation.
Its central function in the body is to serve as an enzymatic cofactor —that is, a molecule that enzymes need in order to work properly— of five human carboxylases, enzymes that catalyze key reactions in the metabolism of carbohydrates, fats and amino acids. We explain this mechanism in detail further on.
What is it for? Functions authorized at European level
At European level, the EFSA (European Food Safety Authority) has assessed the physiological functions of biotin and has officially authorized seven health claims. These claims may be used in the labelling and communication of food supplements that provide at least 15% of the nutrient reference value (NRV) per recommended dose.
Normal energy-yielding metabolism
Biotin contributes to normal energy-yielding metabolism (authorized EFSA claim, ID 113). This function reflects the role of biotin-dependent carboxylases in the metabolic pathways that generate energy from the nutrients we ingest.
Normal metabolism of macronutrients
Biotin contributes to the normal metabolism of macronutrients (authorized EFSA claim, ID 116) — that is, to the processing of carbohydrates, fats and proteins. This claim is tied to the specific function of the carboxylases in each of these pathways.
Normal functioning of the nervous system
Biotin contributes to the normal functioning of the nervous system (authorized EFSA claim, ID 114) and to normal psychological function (authorized EFSA claim, ID 115). These functions are related to its role in brain energy metabolism and in myelin synthesis.
Maintenance of hair, skin and mucous membranes
Biotin contributes to the maintenance of normal hair (authorized EFSA claim, ID 121), to the maintenance of normal skin (authorized EFSA claim, ID 118) and to the maintenance of normal mucous membranes (authorized EFSA claim, ID 117). These three claims reflect the importance of biotin in epithelial tissues with a high rate of cell renewal. Further on (section on hair and nails) we honestly address the difference between these officially authorized claims and the effects sometimes attributed to biotin in commercial marketing.
How it works: cofactor of the five carboxylases
Biotin carries out its biological function as part of five human enzymes called carboxylases, enzymes that add a carboxyl group (—COOH) to their substrate molecules. This seemingly simple reaction is an obligatory step in several central metabolic pathways. The five biotin-dependent carboxylases are:
- Acetyl-CoA carboxylase (ACC): initial step of fatty acid synthesis.
- Pyruvate carboxylase: key step of gluconeogenesis (synthesis of glucose from non-carbohydrate precursors).
- Propionyl-CoA carboxylase: catabolism of branched-chain amino acids (valine, isoleucine) and of odd-chain fatty acids.
- β-methylcrotonyl-CoA carboxylase (MCC): catabolism of the amino acid leucine.
- Methylmalonyl-CoA mutase (in humans it also requires biotin via an adjacent cofactor): catabolism of propionate.
The process by which biotin binds to the apoenzymes to form the active carboxylases is called biotinylation, and it is catalyzed by a specific enzyme (holocarboxylase synthetase). Without sufficient biotin, none of these five carboxylases can work properly and the affected metabolic pathways slow down significantly.
Food sources and daily requirements
Biotin is present in a wide variety of foods. The sources with the highest concentration are:
- Animal organ meats (liver, kidney): especially high content.
- Egg yolk: one of the densest sources among everyday foods. Raw egg white contains avidin, a protein that binds to biotin and blocks its absorption; when the egg is cooked the avidin is denatured and no longer has this effect.
- Nuts (almonds, peanuts, walnuts): a common plant source.
- Seeds (sunflower seeds).
- Legumes (peanuts and soy).
- Fish (salmon, sardines).
- Vegetables (spinach, broccoli, sweet potato).
- Whole grains.
- Brewer's yeast and nutritional yeast.
The nutrient reference value (NRV) in the European Union for biotin is 50 μg/day (micrograms per day, according to EU Regulation 1169/2011 on food information). The international recommendations for adults (adequate intake according to the U.S. National Academies) are 30 μg/day, slightly below the European NRV.
Deficiency: signs and at-risk population
Clinical biotin deficiency is relatively rare in people with a varied diet. The signs described in experimental deficiency or due to specific causes include alopecia (hair loss), skin rashes, nail brittleness, conjunctivitis and, in severe cases, neurological disturbances. Situations that can induce deficiency include:
- Prolonged and high consumption of raw egg white: the avidin in raw egg white binds to dietary biotin and blocks its absorption.
- Chronic treatment with antiepileptics (carbamazepine, phenytoin, valproic acid): these may reduce biotin levels through pharmacokinetic mechanisms.
- Prolonged treatment with broad-spectrum antibiotics: these may alter the gut microbiota and reduce the bacterial synthesis of biotin.
- Pregnancy and breastfeeding: the relative demand for biotin increases.
- Inborn errors of metabolism: such as biotinidase deficiency, a rare genetic disorder that requires specialized medical diagnosis.
- Prolonged total parenteral nutrition without supplementation (hospital clinical context).
Doses and commercial forms
The European NRV of 50 μg/day is usually met through the diet. B-complex supplements typically provide between 50 μg and 5 mg of biotin per dose. The higher doses (1–10 mg/day, a thousand to ten thousand times the NRV) are those used in supplements marketed specifically for "hair and nail health". The available evidence on these doses deserves some qualification (next section).
The most common commercial forms are D-biotin (the natural, biologically active form) and, in higher-end supplements, chelated or enhanced-absorption formulations. The synthetic biotin available is bioequivalent to dietary biotin.
On biotin, hair and nails: what the evidence says
Biotin is one of the supplements most widely marketed specifically for "hair and nail health". This section deserves explicit honesty given the abundant mix of information available in advertising and on social media.
On the one hand, the authorized EFSA claims are explicit: biotin contributes to the maintenance of normal hair, skin and mucous membranes (IDs 121, 118, 117). These claims are based on the recognized role of biotin in epithelial tissues with a high rate of renewal.
On the other hand, the evidence on the effect of biotin supplementation in people without documented deficiency is more nuanced. A review published in Skin Appendage Disorders (Patel et al., 2017) synthesized the available studies on biotin in alopecia and nail disorders, and concluded that the strongest clinical evidence corresponds to populations with previously demonstrated deficiency (for example, people with biotinidase deficiency, alopecia acquired through chronic treatments or pregnancy). In people without deficiency, the data are limited and heterogeneous.
The practical conclusion is that biotin contributes to the normal maintenance of hair, skin and mucous membranes (EFSA green claims) in people who obtain it in adequate amounts, but supplementation at very high doses (mg/day) does not guarantee additional effects in people with an adequate nutritional status.
Safety and interactions
Biotin has a very favorable safety profile. EFSA has not established a tolerable upper intake level (UL), considering it unnecessary; being water-soluble, the excess is eliminated in the urine.
Interference with laboratory tests (important)
Biotin at high doses (≥5 mg/day) can interfere with several immunoassay laboratory tests, altering the results of hormone tests (TSH, T4, T3), cardiac troponin, tumor markers and other determinations that use technology based on the biotin–streptavidin binding. The U.S. FDA and other regulatory agencies have issued specific warnings about this effect. If you have blood tests done, inform your doctor about biotin supplementation and stop taking it at least 72 hours before the blood draw.
Other precautions
No clinically relevant pharmacological interactions have been described at the usual supplementation doses. Pregnancy and breastfeeding are considered safe with doses within the usual range of the B complex.
How to choose a biotin supplement
- D-biotin form: the natural and biologically active form. Avoid supplements that do not specify the isomer.
- Dose consistent with the goal: 50–300 μg/day covers the NRV; higher doses (1–10 mg/day) are those used commercially for "hair and nails" but it is worth reviewing the evidence (previous section).
- Consistency with the B complex: supplementation with isolated biotin is rarely indicated; the coherent approach is as part of a B complex.
- Purity and traceability: third-party certificates of analysis when available.
Biotin in the Pleniage portfolio
In the formulation of PLENIAGE® ENERGY PRO, biotin is part of the complete B complex (B1, B2, B3, B5, B6, B12) that is incorporated together with magnesium citrate, alpha-lipoic acid (175 mg), vitamin C and vitamin E. The formula is designed to provide the B-group vitamins in a coordinated way, in synergy with cofactors and antioxidants involved in cellular energy metabolism. Each ingredient has individual scientific research behind it and, in the case of the B-complex vitamins, officially authorized claims at European level; the specific combination of this formula has not been the subject of its own clinical trial.
This page is part of the Energy and performance cluster. To explore other related components in more depth, see the Vitamin B5 page (another B-complex vitamin in the same formula) and the Magnesium citrate page.
Frequently asked questions about biotin
Are biotin, vitamin B7 and vitamin H the same thing?
Yes, they are three names for the same molecule. "Biotin" is the current chemical name and the most widely used internationally. "Vitamin B7" is the official nutritional designation within the B complex. "Vitamin H" is an older European designation, from the German Haar und Haut ("hair and skin"), after the early observations of its role in skin health. On the labelling of European food supplements any of the three terms may appear.
Is biotin good for hair and nails?
Biotin contributes to the maintenance of normal hair, skin and mucous membranes (authorized EFSA claims IDs 121, 118, 117). These claims apply to people with an adequate intake of biotin. Supplementation at very high doses (several mg/day) in people without documented deficiency has more limited evidence. A review published in Skin Appendage Disorders (Patel et al., 2017) concluded that the strongest evidence corresponds to populations with previously demonstrated deficiency. If you have hair loss or nail brittleness problems, consult your doctor or dermatologist: there are multiple possible causes that require evaluation.
How much biotin do I need per day?
The nutrient reference value (NRV) in the European Union is 50 μg/day. The adequate intake recommended by the U.S. National Academies is 30 μg/day. A varied diet easily covers these amounts. B-complex supplements usually provide 50–300 μg of biotin; commercial supplements for "hair and nails" reach 1–10 mg/day (several thousand times the NRV).
Does biotin have side effects?
It has a very favorable safety profile. EFSA has not established a tolerable upper intake level. The most important precaution is interference with laboratory tests: high doses of biotin (≥5 mg/day) can alter the results of hormone tests (TSH, T4, T3), cardiac troponin and tumor markers. If you have blood tests done, inform your doctor and stop taking it at least 72 hours before the blood draw.
Does raw egg white block biotin?
Yes. Raw egg white contains avidin, a protein that binds to biotin with very high affinity and blocks its intestinal absorption. Regular and high consumption of raw egg white over prolonged periods can induce biotin deficiency. When the egg is cooked the avidin is denatured and loses this binding ability, so cooked egg does not pose this problem.
Are there interactions with medications?
No clinically relevant pharmacological interactions have been described at the usual supplementation doses. It is worth keeping in mind the interference with laboratory tests (mentioned above). Chronic treatment with antiepileptics (carbamazepine, phenytoin, valproic acid) can reduce biotin levels; patients on these treatments should consult their doctor before supplementing.
Is isolated biotin or biotin as part of the B complex better?
It is preferable as part of the complete B complex or of a multivitamin. Biotin is rarely needed on its own. The eight B-group vitamins act synergistically in multiple metabolic pathways, and coordinated supplementation of the complex is more coherent than isolating a single vitamin. Isolated biotin supplements at very high doses (mg/day) are specifically marketed for "hair and nails" but the evidence is nuanced in people without deficiency.
Biotin (vitamin B7 / vitamin H) is a water-soluble B-complex vitamin with seven authorized EFSA green claims, which include its contribution to energy metabolism, to the functioning of the nervous system, to psychological function and to the maintenance of hair, skin and mucous membranes. Its central role is to serve as a cofactor of the five human carboxylases, enzymes that participate in metabolic pathways for the processing of carbohydrates, fats and amino acids. It is obtained through a varied diet and is part of any complete B complex, where it provides its specific function in synergy with the rest of the B-group vitamins.
At PLENIAGE® we publish scientific content on evidence-based supplementation. You can explore the Energy and performance cluster for more pages and related articles.
References
The statements in this article are based on available scientific literature and on the health claims officially authorized by EFSA (European Food Safety Authority).
- EFSA Health Claims Register — biotin: authorized claims ID 113 (normal energy-yielding metabolism), 114 (normal functioning of the nervous system), 115 (normal psychological function), 116 (normal metabolism of macronutrients), 117 (maintenance of normal mucous membranes), 118 (maintenance of normal skin), 121 (maintenance of normal hair). Official source: EU Register of Nutrition and Health Claims.
- EU Regulation 1169/2011 on the provision of food information to consumers — Annex XIII (NRV for biotin: 50 μg/day).
- Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord. 2017;3(3):166-169. PMID: 28879195.
- Said HM. Biotin: biochemical, physiological and clinical aspects. Subcell Biochem. 2012;56:1-19. PMID: 22116691.
- Mock DM. Biotin: From Nutrition to Therapeutics. J Nutr. 2017;147(8):1487-1492. PMID: 28701385.
- FDA Safety Communication. The FDA Warns that Biotin May Interfere with Lab Tests. 2017/2019. FDA Safety Communication.