Biotin (vitamin H or B7) is a water-soluble vitamin that helps the body metabolize fats, carbohydrates, and protein. It also helps maintain a healthy nervous system, nails, hair and skin, among other functions.

Water-soluble vitamins are not stored in the body, so a daily intake is necessary.

The human cells cannot synthesize vitamin B7. However, bacteria in the body can produce biotin, and the vitamin is present in numerous foods.

Biotin therapy may help treat some medical conditions. Some people take supplements to strengthen their nails and hair, but there is a lack of evidence supporting this use.

This article looks at why people need biotin, the recommended intake, sources, and any possible health risks.

Fast facts on biotin

  • Biotin, or vitamin B7, is needed to metabolize fats, carbohydrates, and protein.
  • Deficiency can lead to hair loss and skin problems, but it is rare.
  • Dietary sources include red meat, eggs, seeds, and nuts.
  • Supplements are unlikely to cause harm, but they are not proven to help with hair, skin, and nail health.

The body needs biotin to metabolize fats, carbohydrates, and protein.

It is a coenzyme. This means it functions as a supporting compound for carboxylase enzymes.

These enzymes are involved in:

  • synthesizing, or creating, fatty acids
  • synthesizing the amino acids isoleucine and valine
  • gluconeogenesis, or generating glucose

Biotin is important for a number of functions.

Maintaining a healthy pregnancy

About half of pregnant women in the United States have a mild biotin deficiency. This can lead to atypical development in the fetus.

Folic acid supplementation is recommended both the year before and during pregnancy. It is a good idea to obtain a multivitamin that provides at least 30 micrograms (mcg) of biotin per day, in addition to folic acid, to decrease the risk of a deficiency.

Nails, hair, and skin

Biotin supplements are available alone, combined in a supplement with other B vitamins, or included in a multivitamin.

Many manufacturers of cosmetics claim that biotin supplements may improve the strength and durability of fingernails and enhance hair and skin health. However, there is limited evidence for this in scientific research and much of the existing evidence is old.

A study published in 2015 found that women with thinning hair experienced some reduction in shedding after taking an oral marine protein supplement for 90 days. However, biotin was only one ingredient in this supplement, and the research was sponsored by a company that sells health and beauty products.

Further research is needed to support the use of biotin supplements for this purpose in healthy individuals.

Lowering blood glucose

Several studies have tested biotin’s ability to lower blood glucose in people with type 1 and type 2 diabetes. Results have been promising.

In a 2013 animal study, researchers found that biotin may stimulate the secretion of insulin from the pancreas and subsequently lower blood glucose.

Research from 2016 indicated that biotin may assist with glycemic control in people with type 1 diabetes.

Medical professionals need more studies before they can confirm biotin’s effects on blood sugar.

Managing neuropathy

Biotin is necessary for the activity of pyruvate carboxylase. Without this, high levels of pyruvate and aspartate may arise, and this can adversely affect the nerves.

For this reason, biotin may be able to help reduce nerve damage in people who have diabetes or who are undergoing dialysis for kidney disease. However, more evidence is needed to confirm this.

In 1990, scientists found that three people who took a high dose of biotin for 1–2 years saw an improvement in symptoms.

A 2021 study showed biotin may be able to help with neuropathic pain. However, the study was based on rats and not on human subjects.

Biotin-responsive basal ganglia disease

This is a rare, inherited disorder. It affects a part of the nervous system that controls movement. It can lead to involuntary tensing of muscles, muscle rigidity, muscle weakness, and other problems.

The condition appears to respond to treatment with thiamin and biotin.

Treating multiple sclerosis

Studies have suggested that high dose biotin therapy might help improve symptoms in people with multiple sclerosis (MS). This is an autoimmune disease that affects the nervous system, leading to muscle weakness and a range of other problems.

Results published in 2016 suggested that biotin was a safe therapy. In some participants, a high dose taken three times daily reduced symptoms after 9 months of use.

Most people get enough biotin from their diets, and they do not need supplements. For this reason, there is no recommended daily allowance for biotin.

However, biotin does have adequate intake (AI) levels, which are amounts that ensure nutritional adequacy. The AI levels for biotin are:

Life stageAI levels
birth to 6 months5 mcg
infants 7–12 months6 mcg
children 1–3 years8 mcg
children 4–8 years12 mcg
children 9–13 years20 mcg
teens 14–18 years25 mcg
adults 19+ years30 mcg
pregnant people30 mcg
breastfeeding people35 mcg

According to the National Institutes of Health, the average person in a western population consumes 35–70 mcg of biotin daily from foods they eat. For most people, a supplement will not be necessary as long as they are eating a healthy, varied diet.

The Institute of Medicine suggests an AI of 30 mcg per day for adults ages 19 years and over.

Biotin deficiency is rare in humans because biotin is widely available in foods, and the “good” gut bacteria can usually synthesize more biotin than the body needs.

Signs of deficiency include:

  • hair loss, or alopecia
  • a scaly, red rash around the eyes, nose, mouth, and genitals
  • depression
  • lethargy
  • hallucinations
  • numbness and tingling in the hands and feet
  • a loss of control of bodily movements, known as ataxia
  • seizures
  • weakened immune function
  • increased risk of bacterial and fungal infections

Biotin deficiency is most likely to arise in:

  • people during pregnancy
  • people receiving prolonged intravenous nutrition
  • infants who consume breastmilk with low amounts of biotin
  • people with weak biotin absorption due to an inflammatory bowel disease or other gastrointestinal tract disorder
  • people who smoke

It may also affect:

  • those who use medications for epilepsy, such as phenobarbital, phenytoin, or carbamazepine
  • those with liver disease

Learn more about biotin deficiency.

Biotinidase deficiency

Biotinidase deficiency is another cause of biotin deficiency. This is an autosomal recessive metabolic disorder.

In people with this condition, the body does not produce enough of the enzyme needed to release biotin from proteins in the diet during digestion or from typical protein turnover in the cells.

Around 1 in 60,000 newborns have profound or partial biotinidase deficiency. In a profound deficiency, there is less than 10% of normal enzyme activity. In a partial deficiency, 10–30% of normal enzyme activity takes place.

Food should be the first choice when looking for sources of biotin. Biotin in foods usually binds to protein.

Foods that are rich in biotin include:

  • baker’s yeast
  • wheat bran
  • organ meats
  • cooked, whole eggs
  • oysters

Raw eggs contain a glycoprotein called avidin that inhibits the absorption of biotin. Eating two or more raw egg whites a day for several months has been linked to biotin deficiency.

Here are some specific foods and amounts of biotin:

  • 3 ounces (oz) of cooked liver: 30.8 mcg
  • 1 large, whole cooked egg: 10 mcg
  • 3 oz of canned pink salmon in water: 5 mcg
  • 1 oz of cheddar cheese: 0.4 to 2 mcg
  • 1 cup of sweet potato: 4.8 mcg
  • 3 oz of cooked hamburger patty: 3.8 mcg
  • 1 cup roasted sunflower seeds: 9.6 mcg
  • 1 cup of roasted almonds: 6 mcg

Many foods, such as fruits and vegetables, contain a small amount of biotin.

There is no evidence that most people need to take biotin supplements, and there have been no reports of a severe biotin deficiency in any healthy person consuming a balanced diet.

A well-balanced diet is likely to supply most people’s needs unless a doctor advises them otherwise.

Anyone who is considering taking biotin supplements should first check with a doctor.

Can biotin be harmful?

Some biotin supplements contain 2,500 mcg or more, which is significantly higher than the suggested dose for most adults. However, while a person may get an upset stomach, there is no evidence to suggest these high doses are dangerous.

One potential risk of taking biotin supplements is that it may interfere with getting accurate results from blood tests.

In 2019, the Food and Drug Administration (FDA) warned that biotin can cause a blood test to show that a person has a low count of troponin, which is a marker necessary for the diagnosis of heart problems.

How much biotin does a person with a biotin deficiency need?

Those with biotinidase deficiency usually start with a dose of 5–20 milligrams per day.

However, those who do not have biotinidase deficiency should first try to get enough biotin from their diet, as dietary biotin also enhances the intake of other beneficial nutrients that work alongside it.

A person should always speak to a doctor before taking supplements and choose brands carefully, as supplements are not monitored by the FDA.

Is biotin safe for the kidneys?

There is no evidence that biotin can harm the kidneys themselves. However, there is minimal research showing that biotin can cause atypical hormone test results in people with chronic kidney disease.