Whenever I shop at a big box retailer, I like to browse their dietary supplement offerings to stay aware of any new products.

Increasingly, I’ve noticed more products that offer targeted health solutions, especially around hair growth and thickness.

Most of the products contain multiple ingredients. Biotin, a water-soluble B vitamin, is almost always one of them.

Similarly, many shampoos and conditioners that promise thicker, fuller hair often contain this B vitamin.

The reoccurring theme here is that biotin, whether taken as a supplement or lathered in your hair, supposedly benefits hair growth.

This article explains the link between biotin and hair health and whether the vitamin is effective and safe for hair growth or preventing hair loss.

Share on Pinterest
Granger Wootz/Getty Images

Biotin has many benefits for your body.

Its primary role is to help turn the food you eat into energy. Your body also needs it to produce keratin — the type of protein that makes up hair, skin, and nails (1).

Many foods contain biotin, meaning that deficiency is rare in healthy people who eat a balanced diet (2).

Although rare, biotin deficiency can cause skin rashes, brittle nails, as well as hair thinning and loss. This owes to the vitamin’s role in keratin production (2, 3).

As such, biotin supplements and biotin-added hair products are commonly advertised to support healthy hair growth or promote thicker, voluminous hair.

Despite these claims, though, there’s limited evidence to suggest that supplementing with biotin or lathering it through your hair promotes hair growth in non-deficient people.

In an older 2012 study, women with self-perceived thinning hair were randomized to receive either a multi-ingredient hair growth supplement that contained biotin or a placebo for 6 months (4).

Those who received the hair growth supplement reported a visible increase in overall hair volume, scalp coverage, and thickness after the treatment period. Meanwhile, no significant changes were seen in the placebo group.

However, because the hair growth supplement contained multiple ingredients — including zinc and iron, which are also necessary for hair growth — it’s not possible to attribute the study’s findings to biotin alone.

Further, the study was small, and it’s possible that the participants were deficient in one or more nutrients present in the supplement that affect hair health. Any such deficiency could have been corrected through the study period, resulting in hair growth.

In a different study, researchers found that children who experienced improved hair growth or quality after taking biotin supplements all had an underlying condition that caused a biotin deficiency (3).

Outside of these studies, there is no strong evidence to support taking biotin supplements or using biotin-added hair products to promote hair growth (2).

Summary

A biotin supplement can help correct a biotin deficiency and restore hair health and growth. No strong evidence supports using biotin supplements or biotin-added hair products to promote hair growth in non-deficient people.

Although the evidence to support biotin alone for hair growth is weak and limited, the evidence is slightly stronger for preventing hair loss.

Still, biotin supplements are only likely to prevent hair loss and promote hair growth in people with a biotin deficiency.

In one study, a biotin deficiency was found in 38% of women complaining of hair loss. Of these participants, 11% had a history of deficiency risk factors, such as inflammatory bowel disease (IBD) or the use of certain medications like antibiotics (5).

While this study didn’t assess the effects of biotin supplements or biotin-added hair products on preventing hair loss, it demonstrates the link between hair loss and inadequate biotin levels.

Other causes of hair loss include (5, 6):

  • androgenetic alopecia, also known as female pattern baldness
  • rapid weight loss
  • other nutritional deficiencies like iron, zinc, or protein
  • certain hormonal diseases like thyroid disorder

Due to the multiple factors involved in hair loss and thinning, supplementing with biotin without determining the cause can prevent or delay the appropriate treatment in instances where a biotin deficiency isn’t at fault.

Even in cases where a biotin deficiency is present, biotin supplements may not necessarily prevent hair loss.

For example, researchers in one study prescribed a biotin supplement to 22 patients with low biotin levels for hair loss following gastric sleeve surgery (6).

After 3 months, 5 of the patients reported a significant decline in hair loss, 14 reported a small effect, and 3 reported no effect, demonstrating that other factors may also be at play when it comes to hair loss and its prevention.

Summary

Because hair loss is sometimes associated with a biotin deficiency, correcting a deficiency with supplements can prevent hair loss in some people. However, hair loss can be a consequence of several other factors, too.

Normally, the Food and Nutrition Board at the National Academies of the Sciences, Engineering, and Medicine sets a recommended dietary allowance (RDA) for each nutrient.

When there isn’t enough data to set an RDA for a nutrient, which is the case with biotin, the board instead sets an adequate intake (AI). This is the nutrient level assumed to be adequate for most people (7).

The AI for biotin is 30 mcg for adults and 35 mcg for women who breastfeed (2).

You can easily meet these recommendations by enjoying a balanced diet. In fact, it’s estimated that people living in the United States get about 35–70 mcg per day of biotin (2).

Here’s are some of the best sources of biotin (2):

FoodMicrograms (mcg)Daily Value (DV)
Beef liver, 3 ounces (85 grams)30.8103% of the DV
Egg, whole1033% of the DV
Salmon, 3 ounces (85 grams)517% of the DV
Pork chop, 3 ounces (85 grams)3.813% of the DV
Hamburger patty, 3 ounces (85 grams)3.813% of the DV
Sunflower seeds, 1/4 cup (33.2 grams)2.69% of the DV
Sweet potato, 1/2 cup (76.9 grams)2.48% of the DV
Almonds, 1/4 cup (36 grams)1.55% of the DV

Eggs are a good source of biotin, but avoid consuming them raw to get the most of the vitamin. Raw egg whites contain avidin, a type of sugar protein, which tightly binds biotin, preventing your body from absorbing it.

Cooking destroys avidin, allowing you to absorb biotin. Thus, it’s best — both for your safety and nutrition — to avoid raw eggs (2).

The Food and Drug Administration (FDA) doesn’t require food manufacturers to list biotin on their labels unless they add it to their products.

In addition to food, the bacteria in your intestines can make biotin. However, the role of gut bacteria on the overall biotin status of humans remains unknown — in part due to the complexity of the gut microbiota and the factors that influence its composition (8).

Summary

People in the United States generally meet or exceed the daily recommendation for biotin. Animal-based foods like eggs, meat, and fish tend to be the best source, but some seeds, nuts, and vegetables also contain it.

Biotin supplements are generally unnecessary unless you have a biotin deficiency or a risk factor that increases your risk of a deficiency.

People most at risk for a biotin deficiency include those with (2, 9):

  • Biotinidase deficiency (BTD). A genetic disorder in which the body is unable to reuse and recycle biotin. Newborns in the United States and many other countries are screened for this disorder.
  • Chronic alcohol use. Because alcohol inhibits biotin absorption, long-term alcohol use is associated with significant reductions in biotin levels.
  • Malnutrition. Inadequate food and nutrient intake can lead to low nutrient levels, including biotin.
  • Inflammatory bowel diseases (IBDs). Crohn’s disease and ulcerative colitis can decrease the gut bacteria’s production of biotin.

Those who are pregnant and breastfeeding can also develop low biotin levels despite normal dietary intake of the vitamin. This may be due to increased use of the vitamin, impaired absorption, or both (10).

People who take certain classes of medications like antiepileptics and retinoids are also at risk of a biotin deficiency (9).

Antiepileptics are commonly used to treat seizure disorders, nerve pain, and bipolar disorder. Retinoids are a class of compounds derived from vitamin A, commonly used to treat acne, psoriasis, and other dermatological conditions (11).

Outside of these populations, biotin supplements or biotin-added hair products are unlikely to offer any benefits (12).

Summary

People at risk for biotin deficiency include people with BTD, chronic alcohol use, malnutrition, and IBD. Those who are pregnant and lactating as well as those who take certain medications are also at an increased risk.

Biotin taken as a dietary supplement is relatively safe and unlikely to have toxic effects since it’s water-soluble (1).

However, an overdose of biotin may cause insomnia, excessive thirst, and urination (13).

Taking them can also cause high biotin levels in your blood, which can interfere with certain lab tests, including those used to measure thyroid hormones, vitamin D, and heart health (2).

That’s because many lab tests utilize biotin due to its ability to bind with specific proteins and detect certain health conditions (14).

Therefore, always let your doctor know of any supplements you take or plan to take that contain biotin. These may include some prenatal and multivitamins.

It’s also worth noting that some antiepileptic drugs — like carbamazepine, primidone, phenytoin, and phenobarbital — can lower biotin levels.

If you take any of these, talk to your doctor or a dietitian to ensure you’re getting enough biotin, either through your diet, with a supplement, or a combination.

Summary

Biotin supplements are generally safe to take, but they can interfere with certain lab results. Thus, keep your healthcare provider in the loop of any supplements you take that may contain this vitamin.

There’s no strong evidence to support using biotin for hair growth or to prevent hair loss in people without a deficiency.

Because hair thinning and poor hair growth are sometimes associated with a biotin deficiency, correcting a deficiency can help restore hair growth in some people.

Several other factors can also cause hair loss and thinning, including a deficiency in other nutrients like iron and zinc.

Most people get plenty of biotin from their diets. Yet, some conditions, lifestyle habits, and medications can cause low levels.

If you plan to take a supplement with biotin, let your doctor know before having any blood tests done since the vitamin can interfere with certain lab test results.

Just one thing

Try this today: Biotin isn’t the only vitamin researched for its possible hair growth benefits. Stop by this article to see the 5 best vitamins and 3 other nutrients for hair growth.

Read this article in Spanish.