Biotin is a B-vitamin found in many foods. Biotin helps turn the carbohydrates, fats, and proteins in the food you eat into the energy you need.

The amount of biotin you need each day depends on your age. Average daily recommended amounts are listed below in micrograms (mcg).

Many foods contain some biotin. You can get recommended amounts of biotin by eating a variety of foods, including the following:

• Meat, fish, eggs, and organ meats (such as liver)
• Seeds and nuts
• Certain vegetables (such as sweet potatoes, spinach, and broccoli)

Biotin is found in some multivitamin/multimineral supplements, in B-complex supplements, and in supplements containing only biotin.

Most people get enough biotin from the foods they eat. However, certain groups of people are more likely than others to have trouble getting enough biotin:

• People with a rare genetic disorder called “biotinidase deficiency”
• People with alcohol dependence
• Pregnant and breastfeeding women

Biotin deficiency is very rare in the United States. Biotin deficiency can cause thinning hair and loss of body hair; a rash around the eyes, nose, mouth, and anal area; pinkeye; high levels of acid in the blood and urine; seizures; skin infection; brittle nails; and nervous system disorders. Symptoms of biotin deficiency in infants include weak muscle tone, sluggishness, and delayed development.

Scientists are studying biotin to understand how it affects health. Here is an example of what this research has shown.

Hair, nail, and skin health

Dietary supplements that contain biotin are often promoted to improve the health of your hair, skin, and nails, but there is little scientific evidence to support these claims. In a few small studies, some people with thin and brittle nails who took high doses of biotin had harder nails. Doctors have also reported that in a few cases, high doses of biotin have improved a rare hair disorder in children and skin rash in infants. More research is needed before biotin supplements can be recommended for any of these conditions.

Biotin has not been shown to cause any harm. However, supplements that contain biotin above recommended amounts may cause false results in some lab tests, including those that measure levels of certain hormones, like thyroid hormone.

Yes, some medications you take may affect your biotin levels, and biotin may interact with certain medications. For example, treatment for at least 1 year with antiseizure medications (used to treat epilepsy) can significantly lower biotin levels.

Tell your doctor, pharmacist, and other healthcare providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if the dietary supplements might interact with your medicines or laboratory tests, or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients such as biotin.

Dietary supplement products that are promoted for healthy hair, skin, and nails are readily available, but do they work? Formulations differ, but almost all contain very high doses of biotin.

Biotin is a B vitamin found mainly in meat, eggs, fish, nuts, and some vegetables. A biotin deficiency can cause skin rashes, hair loss, and brittle nails––hence, the belief that taking extra biotin will produce glowing skin, thick hair, and strong nails. But do these claims actually hold up?

One of the most common misconceptions about vitamins and minerals is that if a nutrient deficiency causes a particular set of symptoms, then taking more of that nutrient will not only reverse those symptoms, but will actually leave you better off. The reality is, if you are already getting enough, getting more doesn’t usually help.

Biotin helps metabolize the food we eat into the energy we need. The recommended amount of biotin for adults is 30 micrograms (mcg) per day, and you can get this much by eating a wide variety of nutritious foods. For example, a meal with 3 ounces of salmon, 3/4 cup of cooked sweet potato, 1/2 cup of cooked spinach, 1/4 cup of roasted almonds, and 1 cup of 2 percent milk provides about 11 mcg of biotin.

Some dietary supplements contain between 2,500 and 5,000 mcg of biotin, which are very high doses. In a few small scientific studies, some people with thin and brittle nails who took high doses of biotin had harder nails. And in a few cases, high doses of biotin improved a rare hair disorder in children and skin rash in infants. But the results of these studies are too preliminary to recommend biotin for any of these conditions.

Biotin doesn’t have an upper intake limit because there’s no evidence that it’s toxic, even at high doses. Most vitamins and minerals, however, do have upper limits, and getting too much can be unsafe. Some can also interact with medications or lab tests. Biotin, for example, can cause false results on some lab tests, including those that measure thyroid hormone levels. For these and other reasons, we always recommend talking with your healthcare provider about vitamins, minerals, and other dietary supplements to help you determine which, if any, may be of value.