Biotin is part of the group of B vitamins found in food. It helps the body convert food into energy and plays many other important roles in health. 
Biotin benefits healthy hair and nails, supports a healthy pregnancy, and helps control blood sugar levels, among other benefits. 
This article describes seven roles biotin plays in the body. It also explores the food sources of the vitamin and safety considerations.
Biotin, a B vitamin, is an essential nutrient that is naturally present in some foods and is available as a dietary supplement.
What is biotin?
Biotin is one of the eight B vitamins. Also known as vitamin B-7 or vitamin Hin which case the H stands for «Haar und Haut«, the German words for «hair and skin«.
Biotin is soluble in water. The body does not store water-soluble vitamins, so people must absorb them from their diets and through the food they eat.
Biotin is necessary for the function of several enzymes known as carboxylases. These are part of important metabolic processes, such as the production of glucose and fatty acids.
The Office of Dietary Supplements recommends the following biotin intake per day:
- 30 micrograms (mcg) for adults, including during pregnancy.
- 35 mcg during lactation.
The biotin deficiency is quite rare. However, some people, such as pregnant women and people who drink large amounts of alcohol, may develop mild deficiencies.
Also, eating raw eggs on a regular basis can cause biotin deficiency, because raw egg whites contain a protein called avidin that binds to biotin, preventing the body from absorbing it. Cooking eggs deactivates their avidin.
This water-soluble vitamin is a cofactor for five carboxylases (propionyl-CoA carboxylase, pyruvate carboxylase, methylcrotonyl-CoA carboxylase [MCC]acetyl-CoA carboxylase 1 and acetyl-CoA carboxylase 2) that catalyze critical steps in the metabolism of fatty acids, glucose and amino acids.
Function and benefits of biotin
Biotin performs a number of important functions in the body, including:
1. Breakdown of macronutrients
Biotin helps the body convert food into energy: supports a number of enzymes involved in the breakdown of carbohydrates, fats and proteins.
Specifically, biotin is involved in:
- Gluconeogenesis– This is the synthesis of glucose from sources other than carbohydrates, such as amino acids, and biotin-containing enzymes help start this process.
- Fatty Acid Synthesis: Biotin helps enzymes that activate reactions that are important for the production of fatty acids.
- Amino acid breakdown: Biotin-containing enzymes are involved in the metabolism of several important amino acids, including leucine.
2. Improves nail health
Brittle nails are brittle and easily split or crack. A biotin deficiency can lead to brittle nails.
For people with this deficiency, taking supplements containing biotin might improve the strength of their nails.
Changing your diet and other lifestyle factors can help improve nail health, as can some commercial products.
3. Improves hair health
The diet can play an important role in skin and hair health. For example, some foods for healthy hair include eggs, Brazil nuts, and fatty fish.
Many hair products that claim to promote healthier, stronger hair contain biotin. The biotin deficiency can lead to hair lossindicating that the vitamin is involved in maintaining healthy hair.
However, little research has linked the vitamin to hair health in people who do not have biotin deficiencies.
4. Support during pregnancy and lactation
Biotin is very important for pregnant or lactating women.
Although symptomatic biotin deficiency is rare, low biotin levels are common during pregnancy.
In fact, about 50% of pregnant women in the United States may have at least a mild deficiency. This level of deficiency can affect a person’s health, but not enough to cause noticeable symptoms.
Health professionals believe that this deficiency is common among pregnant women because the body breaks down the vitamin faster during pregnancy.
As a result, a pregnant woman may need more biotinfrom diet or supplements, than a woman who is not pregnant.
That said, it’s important to consult a health professional before taking supplements while pregnant or nursing.
5. Reduced blood sugar in people with diabetes
Type 2 diabetes is a metabolic condition characterized by high blood sugar levels and impaired insulin function.
A biotin deficiency can impair blood sugar regulation or glucosa. Some evidence shows that blood biotin levels may be lower in people with diabetes.
Animal studies have suggested that supplements containing biotin and chromium picolinate might prevent insulin resistance. 
Researchers have also studied how biotin supplements affect blood sugar levels in people with type 2 diabetes. Results have been mixed, but some studies have shown that taking biotin and chromium picolinate might help treat type 2 diabetes. two.
Overall, fully understanding the effects of biotin on diabetes and blood sugar control will require more high-quality research.
6. Improves skin health
Scientists do not fully understand the role of biotin in maintaining healthy skin. Nevertheless, people with biotin deficiencies may experience skin problemssuch as red, scaly rashes.
Some people also believe that biotin can help improve psoriasis.
The influence of the vitamin on the skin may be due to its effect on fat metabolism. This process is important for maintaining healthy skin and can be affected in people with low biotin levels.
It is important to note that no evidence shows that biotin improves skin health in people who do not have a deficiency of the vitamin.
7. Support in the treatment of multiple sclerosis
Multiple sclerosis (MS) is an autoimmune disease. It damages the protective covering of nerve fibers in the brain, spinal cord, and eyes.
This protective covering is called myelin, and biotin may play an important role in its production.
Studies have shown that people with MS respond positively to daily biotin doses of up to 300 milligrams (mg). This supplementation can reverse disease progression and reduce chronic disability. 
What are good sources of biotin?
Biotin exists in a wide variety of foods, which helps explain why a deficiency in the vitamin is fairly rare.
Foods that are particularly rich in biotin include:
- organ meats, such as liver and kidney;
- egg yolks;
- legumes, such as soybeans and peanuts;
- green leafy vegetables;
- nuts and nut butters.
In addition, intestinal bacteria produce some biotin. Some people take supplements that contain biotin on its own or in a combination of vitamins.
Biotin is a water-soluble vitamin, and any amount not absorbed by the body is excreted in the urine.
However, there have been some reports of high doses of biotin causing strange thyroid test results. Anyone who has thyroid disease can benefit from consulting with a doctor before trying a biotin supplement.
- Zempleni, J., Wijeratne, SS, & Hassan, YI (2009). Biotin. BioFactors (Oxford, England), 35(1), 36–46. https://doi.org/10.1002/biof.8
- Valdés-Ramos, R., Guadarrama-López, AL, Martínez-Carrillo, BE, & Benítez-Arciniega, AD (2015). Vitamins and type 2 diabetes mellitus. Endocrine, metabolic & immune disorders drug targets, 15(1), 54–63. https://doi.org/10.2174/1871530314666141111103217