Written by Maria Robinson, MD, MBA | Reviewed by Sophie Vergnaud, MD
Key takeaways:
Biotin is an important vitamin that keeps you healthy by turning the food you eat into energy.
Many people take extra biotin to help their hair and nails grow, but there isn’t much research to back up these claims.
People with brittle nails and those with hair loss and low biotin levels may benefit from taking extra biotin.
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If you take biotin for hair or nail health, you’re not alone. Almost 20% of Americans consume some type of biotin, and they don’t always tell their healthcare providers. Biotin is found in many health and beauty products, and even some physicians recommend it.
With all this marketing and hype, many people assume that biotin works to improve hair and nail health. But is this actually true? It turns out there’s not much science to back up these claims.
Let’s take a look at what the research shows, when biotin may be helpful, and how taking too much of it can affect some lab test results.
What is biotin?
Biotin (vitamin B7) is a B vitamin that’s found in many foods — like fish, meat, seeds, and some vegetables (like sweet potatoes). Some bacteria in the intestines also make biotin, which is then absorbed into the body.
So what is biotin good for? Biotin is needed for your cells to work correctly. It helps cells break down fat, glucose (sugar), and protein. It also helps regulate your genes and how cells communicate with each other.
What does biotin do for hair and nails?
If you walk down the supplement aisle, you may notice that biotin seems to be everywhere. There’s biotin for hair loss and biotin for nails, and it’s often combined with other vitamins. But does it really work?
It turns out that there’s not much research to back up the claim that biotin works for hair or nail growth. Let’s take a look at each one separately.
Does biotin work for hair loss?
There’s no evidence that it does. Several studies have looked at the effect of biotin on hair growth. Based on the results, it’s not possible to prove that taking biotin helps hair grow. There are a few reasons for this:
The studies were not of good enough quality to prove that it works. None of the studies were randomized controlled trials, the strongest type of study.
Many people in the studies had low levels of biotin caused by inherited health conditions. Most people don’t have low levels of biotin, so we can’t apply the results of these studies to the general population.
Many studies didn’t describe in detail the type of hair loss being treated. It’s possible that hair would have regrown even without the biotin.
So far, biotin only seems to help people who have low biotin levels. This may be the case for some people with hair loss. One recent study found that almost 40% of women with hair loss had low biotin levels. In this situation, taking biotin may help if there isn’t another reason for hair loss.
Does biotin work to strengthen nails?
Biotin may help some people with brittle nails. Studies show that taking 2.5 mg (2,500 mcg) biotin daily may improve nail firmness, hardness, and thickness. In one study, over half of the people taking biotin 2.5 mg a day had a 25% increase in thickness of their nails.
So far, the studies evaluating biotin and nails have been small and not of the highest quality. This is why more research needs to be done to prove that biotin really helps strengthen nails.
How much biotin should you take for hair and nail growth?
Despite all of this, if you want to try biotin, how much should you take? The daily adequate intake for biotin is 30 mcg for nonpregnant adults. This means that you should consume at least this amount each day. Most people on a Western diet have no problem getting this amount since they get about 35 mcg to 70 mcg of biotin from their food.
Can you take too much biotin?
High doses of biotin probably aren’t toxic. Biotin is water soluble, so the body gets rid of any extra through urine. Even though high doses of biotin aren’t toxic, some people experience symptoms like stomach ache and insomnia.
Risks and side effects of biotin
There aren’t any known side effects of taking regular amounts of biotin. Most people don’t seem to have any problem taking biotin supplements.
But taking high doses of biotin can interfere with the results of certain lab tests. This means that the test results may not be accurate — the actual amount may be higher or lower than what the test reports. Biotin can interfere with the results of these blood levels:
Hormones: like vitamin D and thyroid hormone
Troponin: a blood marker that helps diagnose heart attack
What does work to help regrow hair?
If you’re trying to regrow or thicken your hair, there are some options other than biotin that have been proven to work. This includes different medications and procedures, like:
Minoxidil (Rogaine)
Finasteride (Propecia)
Platelet-rich plasma
Microneedling
Hair transplant
Your dermatologist can help you figure out the best treatment plan for your situation.
The bottom line
Biotin is a vitamin that helps your body do many important things, like turn your food into energy. Most people get enough biotin through their diet with things like fish and seeds. Many people take extra biotin for their hair and nail health.
Studies show that biotin only helps hair grow if you have low biotin levels. But some people with brittle nails may benefit from extra biotin. Taking biotin is pretty safe, but keep in mind that it can interfere with the accuracy of certain lab tests.
References
Hochman, L. G., et al. (1993). Brittle nails: Response to daily biotin supplementation. Cutis.
Lipner, S. R. (2018). Rethinking biotin therapy for hair, nail, and skin disorders. Journal of the American Academy of Dermatology.
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