What biotin is and what it does in your body

Biotin is a B vitamin that your body uses to break down food into energy. It plays a role in keeping your hair, skin, and nails healthy, and it helps your nervous system work properly. Your body makes some biotin on its own, and you also get it from foods like eggs, almonds, salmon, and sweet potatoes.

Biotin is sometimes called vitamin B7 or vitamin H. Unlike some vitamins, biotin doesn't build up in your body over time — your body uses what it needs and removes the rest through urine. That's why you need a steady supply from food or supplements.

Most people who eat a varied diet get enough biotin without thinking about it. But some people take extra biotin as a supplement, usually because they're hoping it will improve their hair, skin, or nails, or because they have a condition that affects how their body uses biotin.

Key Takeaways

  • Biotin is a B vitamin that helps your body convert food into energy and supports the health of your hair, skin, and nails.
  • You get biotin from foods like eggs, nuts, fish, and vegetables, and most people eating a varied diet get enough without supplements.
  • Some people take biotin supplements hoping to strengthen hair or nails, though research on whether it actually works is mixed.
  • Biotin is water-soluble, meaning your body doesn't store excess amounts, so taking more than you need doesn't typically cause harm.
  • Certain medical conditions and some medications can affect how your body uses biotin, which is why some people need to pay attention to their intake.

Where biotin comes from in food

Biotin is found in many everyday foods, so you don't need to hunt for special sources. Eggs (especially the yolk) are one of the richest sources. Nuts and seeds like almonds, peanuts, and sunflower seeds contain good amounts. Fish like salmon and sardines have biotin, as do beef liver and other organ meats.

Plant-based sources include sweet potatoes, spinach, broccoli, and mushrooms. Whole grains and legumes like lentils and chickpeas also contain biotin. The amount varies depending on the food and how it's prepared — cooking can sometimes reduce biotin content, though the effect is usually small.

If you eat a mix of protein, vegetables, nuts, and whole grains, you're likely getting enough biotin without thinking about it. The recommended daily amount for adults is 30 micrograms, which is a small quantity that most diets easily provide.

Why people take biotin supplements

The most common reason people take biotin supplements is the hope that it will strengthen hair and nails or improve skin. This idea comes partly from the fact that biotin is involved in making keratin, a protein that makes up hair and nails. The logic is straightforward: more biotin might mean stronger hair and nails.

Some people take biotin because they have a diagnosed biotin deficiency, which is rare but can happen with certain digestive conditions, long-term antibiotic use, or genetic disorders. Others take it because they have diabetes or blood sugar concerns — some research suggests biotin might play a role in blood sugar management, though this is still being studied.

People with certain skin conditions, like seborrheic dermatitis, sometimes use biotin as part of their routine. And some people straightforward take it as part of a general vitamin routine, on the assumption that more of a "good" vitamin can't hurt.

What research says about biotin and hair, skin, and nails

The research on whether biotin supplements actually strengthen hair and nails is mixed. Some studies show modest improvements in nail thickness or brittleness, particularly in people who had low biotin levels to begin with. Other studies show little to no difference between biotin and a placebo.

For hair, the evidence is even thinner. Most studies that show benefits involve people with an actual biotin deficiency, not people with normal biotin levels taking extra. If you already get enough biotin from food, adding more may not change anything about your hair growth or thickness.

For skin, there's limited research on biotin supplements in people without a deficiency. Some small studies suggest it might help with certain skin conditions, but the evidence isn't strong enough for doctors to routinely recommend it for general skin health.

The takeaway: if you have a diagnosed deficiency or a specific condition, biotin might help. If you're taking it hoping for thicker hair or stronger nails and you already eat a normal diet, the evidence that it will work is weak.

How much biotin is safe to take

Biotin is water-soluble, which means your body doesn't store it. Excess biotin is filtered out through your kidneys and removed in urine. Because of this, biotin supplements are considered very safe, and there's no established upper limit for how much you can take without harm.

Most biotin supplements sold over the counter contain 2.5 to 10 milligrams per dose — much more than the 30 micrograms you need daily. People taking these doses have not reported serious side effects in research studies. Some people report mild side effects like nausea or skin rashes, but these are uncommon.

That said, more biotin doesn't automatically mean better results. Taking 100 times the recommended amount won't give you 100 times the benefit — your body will straightforward use what it needs and excrete the rest.

When biotin deficiency actually happens

True biotin deficiency is rare in people eating a normal diet. It's most likely to occur in people with certain genetic conditions that affect how the body processes biotin, or in people with digestive disorders that prevent nutrient absorption — conditions like Crohn's disease or celiac disease.

Long-term use of certain antibiotics can also reduce biotin levels, as can some anti-seizure medications. Pregnancy and breastfeeding slightly increase biotin needs, though most pregnant people still get enough from food. Raw egg whites contain a protein called avidin that binds to biotin and prevents absorption, so people who eat large amounts of raw eggs over time might develop a deficiency.

If you have a condition that affects nutrient absorption or you take medications that interfere with biotin, your doctor might recommend checking your biotin level or taking a supplement. But for most people, deficiency is not a concern.

How biotin supplements interact with tests and medications

One important thing to know: biotin supplements can interfere with certain blood tests, particularly tests that measure thyroid hormones, troponin (a heart marker), and some hormone levels. If you take biotin supplements and you're having blood work done, tell your doctor or the lab technician before the test. You may need to stop taking biotin for a few days before the test, or the lab may need to use a different testing method.

Biotin doesn't interact significantly with most medications, but it's still worth mentioning to your doctor or pharmacist that you're taking it, especially if you're on medications for diabetes or thyroid conditions. Some medications can affect biotin absorption, and your doctor should know the full picture of what you're taking.

Frequently Asked Questions

Will biotin supplements make my hair grow faster?

There's no strong evidence that biotin supplements speed up hair growth in people who already get enough biotin from food. Some studies show modest improvements in hair quality for people with a biotin deficiency, but if you eat a normal diet, adding more biotin probably won't change how fast your hair grows.

Can I take biotin every day?

Yes, biotin is safe to take daily. Because it's water-soluble and your body doesn't store it, taking it regularly won't cause buildup or toxicity. Most people taking biotin supplements take it daily without problems.

What's the difference between biotin and other B vitamins?

Each B vitamin has a different job in your body. Biotin helps with energy production and supports hair, skin, and nails. Other B vitamins like B12 and folate have different roles — B12 supports nerve function and red blood cells, while folate is important for cell division and DNA. You need all of them, and they work best when you get them from a varied diet.

Do I need a biotin supplement if I eat eggs regularly?

Probably not. Eggs are one of the best sources of biotin, and eating them regularly means you're likely getting enough. A supplement would only make sense if you have a diagnosed deficiency, a condition that affects nutrient absorption, or you're taking a medication that interferes with biotin.

Can biotin cause side effects?

Serious side effects from biotin are very rare. Some people report mild nausea, skin rashes, or digestive upset, but these are uncommon even at high doses. The main thing to watch for is interference with blood tests — tell your doctor if you're taking biotin before any lab work.