A biotin deficiency may lead to hair loss, and supplements may aid hair growth in people with this deficiency. But, evidence has not shown that biotin supplements can boost hair growth in those without a deficiency.

Biotin is an essential B vitamin that helps the body get energy and nutrients from carbohydrates, proteins, and fats.

Biotin is a critical vitamin for bodily function. Many foods — including egg yolks, nuts, and legumes — contain small amounts of biotin. Bacteria in the large intestine also produce biotin. A person will usually get enough biotin from these two sources.

However, additional supplementation may be necessary during pregnancy or if a person has a biotin deficiency.

Some people recommend biotin supplementation to aid hair growth. However, there is no clinical evidence to support its use for this purpose.

This article will discuss the impact that biotin has on hair growth. It will also look at recommended intakes, possible side effects, and the impact of deficiency.

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Anecdotal claims that biotin can aid hair growth are common, and its popularity among consumers is high.

However, according to an analysis of available studies, there have not been any clinical trials to support the use of biotin supplementation to improve hair health, except in people born with deficiencies.

Although some studies have suggested links between biotin deficiencies and alopecia, further analysis has not found conclusive proof of benefit among healthy individuals.

The Food and Drug Administration (FDA) does not have a daily recommended dietary allowance for biotin. However, according to estimates, an intake of 30 micrograms (mcg) may be adequate.

The average intake of biotin in Western countries, excluding the United States, is an estimated 35–70 mcg per day.

It is rare for a person to have a biotin deficiency, and most people in the U.S. naturally get enough from gastrointestinal bacteria and a balanced diet.

Can you take too much biotin?

Most people get adequate amounts of biotin from internal production and diet.

However, people with biotin deficiencies and those who are pregnant or breastfeeding may require biotin supplementation.

Healthcare professionals may prescribe a dosage of as little as 5 milligrams per day for a person with a biotin deficiency. However, the range of required supplementation may differ depending on individual circumstances.

The FDA has warned that biotin might interfere with certain laboratory tests. It stated that samples from people who had consumed high levels of biotin through supplements could provide “clinically significant incorrect” laboratory results.

The FDA reported an increase in adverse effects due to falsely high or low results. A high concentration of biotin in samples can compromise diagnostic tests in which biotin is a key component.

This may be the case for tests looking at troponin levels and thyroid function. According to an analysis, most biotin-related false results occur in thyroid disease-related tests.

Due to the body’s reliance on internal production and dietary intake for biotin levels, anything that causes malnutrition or interferes with gastrointestinal function can contribute to the development of a biotin deficiency.

The metabolic requirements of pregnancy may also lead to biotin deficiencies in some cases. Medical guidance has also suggested that genetic conditions affecting intestinal bacteria balances may result in biotin production deficiencies.

Other factors that can contribute to biotin deficiencies include:

  • too much avidin, which is a compound present in foods such as raw eggs that impairs biotin absorption
  • long-term use of anticonvulsant medications
  • gastrointestinal conditions that prevent the absorption of biotin
  • chronic use of alcohol or intravenous drugs
  • isotretinoin, which is an acne medication
  • gastrectomy or partial gastrectomy
  • antibiotics
  • smoking

Biotin deficiencies are rare, so research into their symptoms is limited. However, a few studies have suggested causal links between biotin deficiency and some conditions.

For example, a 2016 study found that of female respondents complaining of hair loss, 38% had an underlying biotin deficiency, suggesting a correlation between the two. An animal study also found a correlation between biotin and zinc homeostasis in the skin.

However, it is essential to note that controlled human tests have not confirmed direct causality for either of these findings and that further research is necessary.

Some other symptoms of biotin deficiency may include:

  • hair loss
  • confusion or memory problems
  • rashes, especially around the nose and mouth
  • nausea and abdominal cramping
  • muscle pain and cramping

Foods with a notable concentration of biotin include:

Various other nutritional supplements could improve hair health. However, human trials have not supported the efficacy of many of these remedies for this purpose.

Some popular nutrients that may also help with hair growth and thickness include:

There is no firm scientific evidence to support the use of biotin supplements to improve hair growth unless a person has a specific biotin deficiency.

Although there is little evidence of direct health consequences of biotin supplementation, excessive intake may interfere with laboratory test results.

Many other available natural remedies may support hair growth. However, like biotin, many of these are not scientifically proven to have a positive effect.

It is important for individuals experiencing unexpected or unusual hair loss to speak with a doctor. In most cases, biotin deficiencies are not the cause of hair loss, but they may be a contributing factor.