On the Shelf

Mickie Cathers

Biotin has been at the top of supplement charts for years, promoted as being beneficial for shiny, thick hair; strong and fast-growing nails; and healthy, radiant skin. Some biotin dietary supplements also claim to support energy, metabolism, and the nervous system. But is biotin clinically efficacious or just a trend?

Background

Biotin (vitamin B7 or vitamin H) is a water-soluble essential nutrient found in foods such as beef liver, eggs, fish, seeds, nuts, and some vegetables such as sweet potatoes. Biotin acts as an essential cofactor for multiple carboxylases involved in the metabolism of amino acids, fatty acids, and glucose. Biotin also plays key roles in histone modifications, cell signaling, and epigenetic regulation. Most biotin in foods is bound to protein, though some dietary biotin is in the free form. Free biotin is absorbed in the small intestine while most biotin is stored in the liver. Excess biotin is excreted in the urine.

Biotin deficiency may cause brittle nails, thinning of hair, and a red scaly rash on the face. However, biotin deficiency is rare and severe biotin deficiency has never been reported. While biotin is necessary for normal body function, most people get the biotin they need from a healthy and balanced diet.

Supplements may help pregnant women who develop marginal biotin deficiency despite normal biotin intake, some smokers, and some patients with alcohol use disorder. However, there is insufficient data to support or recommend biotin supplementation.

Is there a benefit?

Despite its reputation, there is limited research to support biotin supplementation to improve hair, skin, and nail health. Reviews have revealed underpowered studies as well as studies that didn’t include a placebo group or neglected to include a baseline biotin status of study participants. Differences in hair and nail growth were not statistically significant in these studies. Only case reports are available to support claims that biotin supplements promote hair health, and these reports were only in children.

There have been no clinical trials or randomized controlled trials to study biotin’s effect on alopecia, hair quality, or hair quantity in human subjects. There are no recommendations in the literature, or from FDA or NIH, for biotin supplementation due to this lack of evidence.

Dosage and availability

Biotin supplements are available online and on store shelves as chewable tablets, capsules, softgels, gummies, liquid drops, and powders. These products offer biotin alone or in combination with other B-complex vitamins or other multivitamin and multimineral products, such as magnesium, collagen, or keratin. Oral biotin’s absorption rate is 100%, even in doses of up to 20 mg/day. Biotin is also available in creams and other cosmetic products, which typically contain up to 0.6% biotin, as well as intravenously through a health care provider.

Available data are insufficient for determining recommended dosages. FDA doesn’t recommend daily biotin supplementation, except for  breastfeeding or pregnant patients, who are recommended to take from 5 µg/day to 35 µg/day. NIH suggests an adequate daily intake for adults 19 years and older of 30 µg/day.  For children from birth to 18 years, the range is 5 µg/day to 25 µg/day.

What to tell your patients

Though supplementation remains unnecessary in healthy individuals, biotin is generally considered safe, even for children and pregnant and breastfeeding patients. Adverse effects of ingesting too much biotin could include nausea or upset stomach, though this is uncommon. As biotin is water-soluble, excess is excreted in the urine. However, biotin may interfere with the results of some blood lab tests and hormone assays, and can interact with certain medications, including anticonvulsants. Advise patients to mention their supplements when talking with their health care provider. ■