Biotin is one of eight water-soluble B vitamins. The B vitamins help enzymes do their jobs. Biotin is also known as vitamin B7. It is found naturally in some foods and in supplements. Biotin helps enzymes break down fats, carbohydrates, and proteins in food. It also helps to regulate the signals that your cells send, and it has a role in the activity of your genes.
How Much Biotin Do You Need?
There is no recommended daily allowance (RDA) for biotin. Instead, there is an adequate intake (AI) level. Since there is no evidence of a specific amount of biotin that healthy people need, the AI is assumed to be enough. The AI for adults over 19 is 30 mcg daily. Breastfeeding women have an AI of 35 mcg daily.
There is no limit on how much biotin you can take and there is no evidence that it causes harm, even at very high doses.
Biotin deficiency is so rare that a severe deficiency has never been reported in a healthy adult eating a mixed diet. However, in cases of biotin deficiency, the symptoms can include:
- Thinning hair
- Loss of hair all over the body
- Red rash around body openings, including the mouth, eyes, and nose
- Abnormal amounts of acid in the urine
- Eye infections
- Skin infections
- Brittle nails
- Burning sensation in the hands and feet
- Developmental delays in infants
- Decreased muscle tone in infants
- Lethargy in infants
Is Biotin Good for Your Skin, Hair, and Nails?
Biotin supplements are marketed as being good for your skin, hair, and nails. These benefits are suggested in part because some of the symptoms of biotin deficiency affect your skin, hair, and nails. A few case reports and trials have shown some benefit to taking biotin supplements, but there were also some flaws in these studies, including:
- The studies did not measure the participants' biotin levels before the treatment began. There is some research that suggests biotin supplements may benefit people who are deficient in biotin. The studies didn't measure biotin levels before, during, or after to confirm that.
- The types of hair conditions in the studies were not mentioned or were varied. Some hair conditions such as alopecia can resolve without treatment, so there's no proof the biotin supplements caused the improvement.
- There are no published studies that show biotin supplements help grow hair or nails in normal, healthy people.
There is some evidence that biotin may help improve comedonal acne, which is acne that causes blackheads and whiteheads. It may also help control the flaking and irritation that occurs when you take retinoids for acne.
Another study showed that men and women with mild to moderate acne who used a topical cream and took a supplement that contained biotin showed improvement in their acne. The problem with this study is that the oral supplement contained other vitamins and ingredients, so there's no way to know if it was the biotin that caused the improvement.
Food Sources of Biotin
Most people who eat a varied diet get enough biotin without needing to take a supplement. Good food sources of biotin include:
- Cooked eggs
- Beef liver
- Sweet potatoes
Safety Concerns About Biotin
Although biotin supplements are not harmful, even in high doses, there are some safety concerns associated with taking biotin.
May interfere with lab tests. The FDA issued a warning that taking large doses of biotin can cause some lab tests to give incorrect results. Some lab tests use biotin, so when testing people who are taking biotin, the tests may give falsely positive or falsely negative results.
May interact with medications. Biotin can interact with some medicines and some medicines can affect your biotin levels. This includes some medicines used to treat epilepsy such as:
May interfere with your body's ability to absorb other nutrients. Your body absorbs certain nutrients through the same pathway. Taking these nutrients together may interfere with your body's ability to absorb either one. There is also a protein found in raw egg whites that binds to biotin and reduces your body's ability to absorb it.