Biotin, or vitamin B7, is best known for its role in supporting hair, skin, and nail health.* It’s even sometimes referred to as vitamin H – the H standing for Haar or Haut, the German words for hair and skin, respectively. Biotin certainly has an important role in supporting our hair, skin, and nail health – but this B vitamin also does much more.*

Biotin Basics

Vitamin B7 is water-soluble, so the body only uses what it needs and flushes out the rest. Although our bodies can’t make biotin on their own, biotin can be synthesized from intestinal bacteria or obtained through diet and supplementation.

Biotin supports many functions in the body – and although most individuals get the recommended daily amount of biotin, certain groups, such as pregnant women or individuals with health conditions that affect nutrient absorption, can be at risk for deficiency.

Both hair loss and scaly skin can be symptoms associated with biotin deficiency, which is why it is important to either get the recommended amount through diet or supplementation to support healthy skin and hair.*

As for nail strength, in one clinical trial, 45 individuals with brittle fingernails were given 2.5 mg of biotin daily for seven months. Ninety-one percent showed “definite improvement,” demonstrating firmer and harder nails after an average of 5.5 months.1

But what about the other benefits of biotin? A lesser known benefit of this B vitamin is that it promotes energy metabolism.* It helps with the metabolism of fatty acids, amino acids, and carbohydrates – helping convert these nutrients into energy.*2

Biotin also supports blood sugar metabolism.* Biotin in a higher amount, like in Thorne's Biotin-8, promotes glucose metabolism by stimulating glucose-induced insulin secretion in pancreatic beta cells and by accelerating glucose metabolism in the liver.*

Similarly, biotin can enhance muscle insulin sensitivity by increasing the uptake of glucose by muscle cells.* Biotin is also important for healthy nerve function.* Signs of a biotin deficiency can include numbness, tingling, and ataxia.

This B vitamin is also an important vitamin during pregnancy and breastfeeding, because these stages are associated with an increased need for biotin.*3 It is estimated that one-third of pregnant women might have at least a borderline biotin deficiency,4 making it important to include this nutrient in a good prenatal vitamin.

As with any change in diet or supplementation while pregnant or breastfeeding, be sure to talk to your health-care practitioner prior to starting a new dietary or supplement regimen.

Who is at risk for a deficiency of biotin?

While the most serious biotin deficiencies are a result of a rare genetic disorder that are a result of a deficiency of an enzyme called biotinidase, milder deficiencies can be the result of taking certain medications, life situations, or chronic disease such as:4

  • Certain anti-seizure medications
  • Long-term antibiotic use – which disrupts the microbiome and the beneficial bacteria that synthesizes biotin in the gut
  • Crohn’s disease – interferes with absorption
  • Pregnancy – increased demand
  • Excess alcohol use – interferes with absorption
  • Long-term intravenous nutrition

Where to get biotin

The good news is that biotin is easy to get through diet and supplementation.

Some natural dietary sources of biotin include:

  • Egg yolks – but if you eat the egg whites, don’t eat them raw; they contain a protein called aviden, which binds tightly to biotin and prevents its absorption. Cooking partially denatures the protein so it can’t bind as tightly.
  • Avocados
  • Sweet potatoes
  • Cauliflower
  • Beef liver
  • Salmon
  • Almonds
  • Sunflower seeds

In addition to diet, individuals at risk for deficiency or concerned about biotin intake can take vitamin B7 in supplement form. Thorne’s Biotin-8 offers a high amount of biotin (8 mg per capsule).


  1. Floersheim G. Treatment of brittle fingernails with biotin. Z Hautkr 1989;64(1):41-48. [Article in German]
  2. Tong L. Structure and function of biotin-dependent carboxylases. Cell Mol Life Sci 2013;70(5):863-891. doi:10.1007/s00018-012-1096-0
  3. Perry C, West A, Gayle A, et al. Pregnancy and lactation alter biomarkers of biotin metabolism in women consuming a controlled diet. J Nutr 2014;144(12):1977-1984. doi:10.3945/jn.114.194472
  4. All you should know about biotin deficiency. [Accessed 9.23.19]