Biotin is a B-complex vitamin required by every cell in the body. B vitamins are a class of chemically distinct vitamins that help your body process food into energy. Also known as vitamin H, coenzyme R, and vitamin B7, biotin helps the body metabolize fats, protein,^[1] and carbohydrates. The human body needs biotin for normal growth and development, and the vitamin is especially critical for healthy embryonic growth. Biotin can also help maintain healthy hair, skin, and nails.^[2]

Biotin is a water-soluble vitamin, as opposed to fat-soluble. Unused water-soluble vitamins (C and B complex) pass quickly through the body and are excreted in urine. The body does not store them and supplies must be regularly replenished. And, because the body flushes excess amounts, water-soluble vitamins do not generally accumulate to toxic levels.

Biotin is crucial for good health and there are two sources from which the human body obtains it. The first is diet; the second is bacteria. Biotin can actually be synthesized by the microbiome—the beneficial bacteria in the gut.^[3]

Biotin Health Benefits

1. Biotin Assists Metabolic Processes

Biotin is a cofactor required by several carboxylase enzymes for carbon dioxide transfer. In more simple terms, biotin helps your cells metabolize fatty acids and amino acids, and further assists in the chemical formation of glucose from noncarbohydrate sources.^[4] This means that biotin is crucial for maintaining a normal, balanced metabolism.^[5]

2. Biotin Supports Healthy Hair, Skin, and Nails

Biotin is an important nutrient for healthy hair, nails, and skin. A double-blind, placebo-controlled study of women with thinning hair found that biotin may be a capable supplement for encouraging healthy looking hair. The study found that women who took biotin supplements increased their hair count, volume, coverage, and thickness significantly compared to the control group.^[6] A separate study found that biotin can help thicken and strengthen brittle fingernails.^[7]

Biotin deficiency can lead to rashes and skin lesions.^[8] Studies have found that supplementation can help remedy skin problems caused by biotin deficiency.^[9] In one notable instance, dogs with fur and skin conditions were given an oral biotin supplement. Sixty percent of the subjects showed complete recovery after treatment, with a further 31% reporting improvement. Only 9% showed no effect.^[10]

3. Biotin May Improve Glucose Levels

Biotin plays an important role in carbohydrate metabolism. Multiple studies suggest that biotin by itself or in combination with chromium encourages normal blood sugar.^{[11, 12]} Imbalanced blood sugar frequently accompanies low biotin levels;^[13] both animal and human studies have found that adequate biotin supplementation may support healthy blood sugar levels.^{[14, 15]} Further research is necessary to explore this effect before drawing conclusions.

4. Biotin and Pregnancy

Obtaining sufficient biotin is a concern for pregnant women.^[16] Animal tests have found that biotin deficiency can cause birth defects.^[17] Because biotin doesn’t pass easily to the fetus, a biotin deficiency can be magnified between mother and child. Even a mild or borderline biotin deficiency in the mother can result in a severe deficiency for the fetus. This can cause fetal development problems, especially malformations of the skeletal system. According to one study, women who are pregnant or breastfeeding may require more biotin in their diet than reported by current estimates.^[18][16]

Biotin Deficiency

Biotin deficiency is a rare but serious condition. Symptoms include dry skin, dry eyes, hair loss, cracking in the corners of the mouth, inflammation of the tongue, loss of appetite, fatigue, insomnia, and depression.^[3]

The most common causes of biotin deficiency are certain medications and conditions that reduce the body’s ability to absorb nutrients. Biotinidase deficiency is a genetic disorder which prevents the body from properly recycling biotin. Extreme cases can cause seizures, reduced muscle tone, breathing problems, balance problems, deafness, blindness, and candida infection. It can also cause developmental problems in children.^[18] Biotin deficiency can also affect alcoholics and people with inflammatory bowel disease.^[19]

Those suffering from biotin deficiency should avoid egg whites. Eggs whites contain avidin, a protein that binds to biotin and reduces its ability to be absorbed by the body. Biotin deficiency caused by a diet high in egg whites actually has a name—egg white injury, and eczema is a common symptom.^[20] Ironically, egg yolks are an excellent source of biotin.

Fortunately, the symptoms of biotin deficiency are easily remedied. It should come as no surprise that the solution to a biotin deficiency is more biotin.

5 Vegan Foods Rich in Biotin

The very best way to supply your body with the right amount of biotin is to eat plenty of biotin-rich foods. Foods rich in biotin are the same foods that are generally good sources of B vitamins. Animal sources like pork, organ meat, egg yolk, and milk are biotin-rich, but unappealing to those of us on a plant-based diet. Vegan sources include yeast, legumes, avocados, nuts, and (happily) chocolate.^[21]

Vegan Food Sources of Biotin
Food	Serving Size	Biotin (micrograms)
Yeast	1 packet (7 grams)	1.4 - 4
Bread, whole wheat	1 slice	.02 - 6
Avocado	1 whole	2 - 6
Raspberries	1 cup	.2 - 2
Cauliflower, raw	1 cup	.2 - 2

Daily Intake Recommendation

Because biotin has gone relatively understudied compared to other vitamins, no official Recommended Dietary Allowance has been set. A wide range of recommended intakes have been proposed, but a consensus remains elusive. There are even disagreements between branches of the same agencies. The U.S. National Library of Medicine recommends a daily biotin intake of around 30 micrograms (mcg) for adults ^[12], while the National Institutes of Health posits an intake closer to 300 mcg. ^[22]

I recommend a daily intake closer to the high end of that wide spectrum. As a water-soluble vitamin, all excess biotin is quickly passed from the body anyway. The lower figures only report the adequate intake for biotin. Adequate levels are not the same as optimal levels. The optimal amount of biotin for your age, gender, and health situation may be higher. It’s also a “better safe than sorry” situation. Too little biotin can be ruinous to your health, but as a water-soluble vitamin, too much would just pass harmlessly through your system. Individual requirements may vary, but use the following table as a good rule of thumb concerning daily biotin intake.

Life Stage	Adequate Intake (AI) for Biotin, Daily
Infants	50 mcg
Children under 4	150
Adults and Children Over 4	300
Pregnant and Lactating Women	300

Please note that these figures report the adequate intake for biotin. Adequate levels are not the same as optimal levels. The optimal amount of biotin may vary by age, gender, and health situation.

Biotin Side Effects and Considerations

Biotin is non-toxic,^[23] but may interact with certain medications metabolized by the liver.^[12] Always consult a healthcare professional before you start any new supplement. Always take supplements as directed.

Biotin Supplements

While food is always the best way to provide your body with the nutrients it needs, supplementation may be necessary if your diet doesn’t provide consistent, complete nutrition. If you do add a biotin supplement to your diet, understand you have several options. Biotin is available by itself, combined with other B-complex vitamins, or in a general multivitamin. Whichever you decide, make sure it’s a high-quality product. Supplements that provide plant-sourced nutrients instead of synthetic, lab-generated nutrients are ideal. There are several varieties of biotin. I recommend d-biotin, the only form of active, naturally-occurring biotin.

Have you tried biotin supplementation? What was your experience? Be sure to let us know in the comments.

References

1. Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington (DC): National Academies Press (US); 1998. 11, Biotin.


2. “B Vitamins.” MedlinePlus, National Library of Medicine, 4 Oct. 2016. Accessed 5 Oct. 2016.


3. “Vitamin H (Biotin).” University of Maryland Medical Center, University of Maryland, 16 July 2013. Accessed 5 Oct. 2016.


4. Pacheco-Alvarez, D, et al. “Biotin in metabolism and its relationship to human disease.” Archives of Medical Research., vol. 33, no. 5, 3 Dec. 2002, pp. 439–47. Accessed 5 Oct. 2016.


5. Meléndez, Rodríguez. “[Importance of biotin metabolism].” Revista de Investigación Clínica; Organo Del Hospital de Enfermedades de la Nutrición., vol. 52, no. 2, 10 June 2000, pp. 194–9. Accessed 5 Oct. 2016.


6. Glynis, Ablon. “A Double-Blind, Placebo-Controlled Study Evaluating the Efficacy of an Oral Supplement in Women with Self-Perceived Thinning Hair.”The Journal of Clinical and Aesthetic Dermatology 5.11 (2012): 28–34. Print.


7. Colombo, VE, et al. “Treatment of brittle fingernails and onychoschizia with biotin: scanning electron microscopy.” Journal of the American Academy of Dermatology., vol. 23, no. 6, 1 Dec. 1990, pp. 1127–32. Accessed 5 Oct. 2016.


8. Mock, DM. “Skin manifestations of biotin deficiency.” Seminars in Dermatology., vol. 10, no. 4, 1 Dec. 1991, pp. 296–302. Accessed 5 Oct. 2016.


9. Misir, R, and R Blair. “Effect of biotin supplementation of a barley-wheat diet on restoration of healthy feet, legs and skin of biotin deficient sows.” Research in Veterinary Science. vol. 40, no. 2, 1 Mar. 1986, pp. 212–8. Accessed 5 Oct. 2016.


10. Frigg, M, et al. “Clinical study on the effect of biotin on skin conditions in dogs.” Schweizer Archiv Für Tierheilkunde., vol. 131, no. 10, 1 Jan. 1989, pp. 621–5. Accessed 5 Oct. 2016.


11. Albarracin, CA, et al. “Chromium picolinate and biotin combination improves glucose metabolism in treated, uncontrolled overweight to obese patients with type 2 diabetes.” Diabetes/metabolism Research and Reviews., vol. 24, no. 1, 17 May 2007, pp. 41–51. Accessed 5 Oct. 2016.


12. “Biotin.” MedlinePlus, U.S. National Library of Medicine, 16 Sept. 2016. Accessed 5 Oct. 2016.


13. Báez-Saldaña, Armida, et al. “Effects of Biotin on Pyruvate Carboxylase, Acetyl-CoA Carboxylase, Propionyl-CoA Carboxylase, and Markers for Glucose and Lipid Homeostasis in Type 2 Diabetic Patients and Nondiabetic Subjects.” The American Journal of Clinical Nutrition, vol. 79, no. 2, Feb. 2004, pp. 238–243. Accessed 5 Oct. 2016


14. Xiang, X, et al. “[Effects of biotin on blood glucose regulation in type 2 diabetes rat model].” Wei Sheng Yan Jiu Journal of Hygiene Research. vol. 44, no. 2, 23 May 2015, pp. 185–9. Accessed 5 Oct. 2016.


15. Koutsikos, D, et al. “Biotin for diabetic peripheral neuropathy.” Biomed Pharmacother. 1990;44(10):511-4. Accessed 5 Oct. 2016.


16. Perry, Cydne A et al. “Pregnancy and Lactation Alter Biomarkers of Biotin Metabolism in Women Consuming a Controlled Diet.” The Journal of Nutrition 144.12 (2014): 1977–1984. PMC. Web. 5 Oct. 2016.


17. Mock, Donald M. “Adequate Intake of Biotin in Pregnancy: Why Bother?” The Journal of Nutrition 144.12 (2014): 1885–1886. PMC. Web. 5 Oct. 2016.


18. “Biotinidase deficiency.” Genetics Home Reference, U.S. National Library of Medicine, 4 Oct. 2016. Accessed 5 Oct. 2016.


19. Said, Hamid M. “Cell and Molecular Aspects of Human Intestinal Biotin Absorption.” The Journal of Nutrition 139.1 (2009): 158–162. PMC. Web. 5 Oct. 2016.


20. Sydenstricker, V P, et al. “OBSERVATIONS ON THE “EGG WHITE INJURY” IN MAN AND ITS CURE WITH A BIOTIN CONCENTRATE.” 10.1001/jama.1942.02830140029009. Journal of the American Medical Association, vol. 118, no. 14, 4 Apr. 1942, pp. 1199–1200. Accessed 5 Oct. 2016.


21. “Pantothenic acid and biotin”. MedlinePlus, U.S. National Library of Medicine, 2 Feb. 2015. Accessed 5 Oct. 2016.
22. “Daily Value.” National Institutes of Health - Dietary Supplement Label Database, U.S. Department of Health & Human Services, 2016. Accessed 1 Nov. 2016.
    


23. Fiume, MZ, and Cosmetic Ingredient. “Final report on the safety assessment of biotin.” International Journal of Toxicology., vol. 20, 22 Jan. 2002, pp. 1–12. Accessed 5 Oct. 2016.