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Waiting for hair to grow in its own time can feel endlessly long, even for the most patient person. So when someone suggests using a vitamin like biotin to speed up the process, it can seem like a miracle path to your best Pantene-commercial-worthy hair yet.

Biotin is a complex B vitamin that helps convert food into energy and aids in breaking down fat in our bodies. We typically get the biotin we need from food, but many believe that taking extra biotin can boost hair strength, ultimately stimulating thickness and growth.

As is the case when taking any vitamin, biotin has its share of side effects, and it’s really important to know what these are before you start taking it on the regular.

A certain amount of biotin is necessary for our bodies to function properly. This vitamin is in charge of creating energy and helps to keep many systems healthy and in check, such as your liver, nervous system, hair, and eyes.

We know that the natural biotin we get from eating certain foods (more on that in a minute) is essential for our health. But while many suspect that biotin can be effective in treating some medical conditions, there isn’t enough science behind these claims to support them completely. Still, many believe there are benefits to taking extra biotin.

It helps your metabolism

Biotin plays an important role in supporting metabolic function. It helps break down and metabolize carbohydrates and amino acids, and also helps break down fat in your body, all of which helps to create energy.

Research has found that biotin, when combined with chromium picolinate, may raise your metabolic rate of carbohydrates, fats, and proteins.

While this doesn’t mean that biotin can accelerate weight loss, it does show that biotin is essential when it comes to your metabolism and blood sugar control.

It *might* support hair growth

Biotin is often marketed as a vitamin that helps stimulate hair growth and that helps reverse hair loss. Biotin deficiencies have been shown to cause thin and brittle hair, which leads many to believe that the vitamin helps keep hair healthy and may promote growth.

While research has found that while biotin supplements may help promote hair health if someone has a biotin deficiency, there isn’t enough evidence to say definitively that biotin can make your hair grow.

It strengthens nails

One older study from 1989 looked at 45 patients who took 2.5 milligrams of biotin a day, and found that 91 percent of them had “firmer and harder fingernails” after 5 months. Still, there’s not much more evidence that says that biotin will lead to healthier nails or stimulate growth.

A biotin deficiency can also lead to thin, brittle nails that break more often and don’t grow as quickly. Taking biotin supplements may help those who have this deficiency.

It regulates blood sugar

Several promising studies have found that biotin may lower blood glucose in people with type 1 and type 2 diabetes. Animal studies have found that biotin can stimulate the secretion of insulin from the pancreas, which lowers blood sugar.

A 2016 study found that biotin might help with glycemic control in people with type 1 diabetes.

It helps babies in the womb

In rare cases, pregnant women can have a biotin deficiency, and so to promote fetal health, it’s sometimes recommended to take a prenatal vitamin that contains biotin and folic acid while pregnant.

However, taking too much biotin while pregnant could lead to rare side effects that include allergies, acne, or even miscarriage. Always speak to your OB/GYN before taking biotin while pregnant.

It makes skin glow

Someone with a biotin deficiency may experience red rashes or dry, itchy skin, which leads some to believe that biotin plays a role in healthy skin. However, there isn’t enough scientific evidence to support the idea that taking biotin leads to healthier skin.

Biotin may be a readily available supplement, but that doesn’t mean you should take it without speaking to your doctor. Most of us are getting enough biotin through our normal diet and don’t need to add extra through supplements.

What if you take too much biotin?

Like any other vitamin, too much biotin isn’t advised. Always speak to your doctor about the other medications you’re taking before you begin taking biotin.

High amounts of biotin can actually create false positives in laboratory tests for thyroid disease and heart attacks — yikes! One study even found that it can mimic Graves’ disease.

The lesson? Don’t start a biotin regimen without consulting your doctor to figure out the appropriate dosage.

Does biotin cause weight gain?

Some claim that taking biotin can cause you to gain weight. There’s no scientific research out there to definitively back up that claim. However, some studies have shown that taking an excess amount of B vitamins can be linked to the prevalence of obesity and diabetes.

Interactions with certain medications

Some medications you take might affect the levels of biotin in your body, and taking extra biotin may interact with some medications.

According to National Institutes of Health Office of Dietary Supplements, taking some epilepsy medications for at least a year can significantly lower biotin levels.

Always let your doctor or healthcare provider know if you are taking biotin supplements.

You can get your biotin naturally, through the foods you eat, or you can choose to take more by taking supplements or applying topicals.

Biotin-rich foods

The best way to get biotin is through your diet. Keep in mind that cooking the below foods can actually render biotin ineffective, so eating these raw (if possible) mean you’ll get more active biotin.

  • cooked egg yolk
  • nuts such as almonds, peanuts, pecans, and walnuts
  • nut butters
  • soybeans and legumes
  • whole grains and cereals, like oatmeal
  • cauliflower
  • bananas
  • mushrooms
  • wheat germ
  • spinach
  • brie cheese
  • milk
  • pork
  • carrots
  • apples
  • tomatoes
  • yeast
  • oysters

Supplements

Biotin supplements are readily available and can often be purchased in your local drugstore. They can be available in supplements that contain only biotin, or combination supplements that contain other B-complex vitamins. You may also find biotin in multivitamin/multimineral products.

While there’s no recommended daily dosage of biotin and since supplements like these are not monitored by the U.S. Food and Drug Administration for safety, it can be tough to know how much is too much.

Based on scientific findings for “adequate intake levels” — guidelines for how much of a nutrient to consume from food to prevent deficiency — it’s safe to ingest around 30 micrograms of biotin per day for folks age 13 and up.

Regardless, you should always speak to your doctor before adding biotin supplements to your daily routine.

Topical

Topical biotin is available mostly in the form of shampoo, conditioner, or other similar hair products.

The idea is that using these will promote stronger, healthier hair and could boost growth. Again, there’s no evidence that biotin will make your hair stronger, healthier, or longer unless you have a biotin deficiency.

There’s nothing wrong with using biotin hair products and they likely will not do anything negative to your hair.

tl;dr

Biotin is an essential B vitamin our bodies need to function properly. It converts food into energy and is often associated with hair strength and growth.

Research shows that biotin may promote hair health and growth if someone has a biotin deficiency. Beyond that, there’s no strong scientific evidence that shows that excess biotin will make your hair grow.

Biotin may be helpful in regulating blood sugar and may aid in fetal development, although more research is needed.

Too much biotin has never been shown to be harmful (unless you’re pregnant), but it can produce false lab tests. There’s no evidence that biotin can cause weight gain or weight loss.

The best way to get biotin is through your diet, by eating biotin-rich foods. You can also speak with your doctor about taking biotin supplements or use hair products that contain biotin.