Biotin benefits

How is a role in the body separated from the benefit of a supplement?

Biotin is the cofactor of five carboxylase enzymes and takes part in fatty acid, glucose and amino acid metabolism. This role shows that biotin needs to be adequate; it does not show that more, in the absence of deficiency, gives an organ additional benefit. NIH states that claims for hair, skin and nails are supported “at best by a few case reports and small studies.” ^[1]

The headings below give, for each claim, who was studied and the limit of the result. For general information, see the biotin guide.

What does biotin correct in deficiency?

Biotinidase deficiency is a rare inherited disease; the body cannot release free biotin even if intake is normal. According to NIH, if left untreated, neurological and skin symptoms appear and can progress to coma or death in severe forms; because oral biotin started from birth or before symptoms and continued for life can prevent these symptoms, newborns are screened. NIH also reports that hair loss, brittle nails, skin rash and neurological findings are among the symptoms of biotin deficiency. These are the most solid benefits of biotin; however, these symptoms are also seen for other reasons, and a diagnosis of deficiency is not made from the symptom alone. ^[1]

Does biotin lengthen hair or reduce hair loss?

Patel and colleagues conducted a review examining the effectiveness of biotin on hair and nail growth. PubMed was searched for case reports and randomized studies; 18 reported cases in which biotin was used for hair and nail changes were found. In all of them the patient had an underlying condition leading to poor hair or nail growth, and clinical improvement was reported in all. The authors noted that biotin may be useful in acquired and inherited biotin deficiency and in conditions such as brittle nail syndrome or uncombable hair, but that these conditions are rare and that there is not enough evidence for supplements in healthy people. ^[2]

NIH, for its part, lists only case reports in children for hair health; in children with uncombable hair syndrome (a rare disease of the hair shaft), 3–5 mg of biotin per day markedly improved hair health in 3–4 months. NIH adds that new studies need to determine whether biotin improves hair, nails and skin, especially in healthy people. For this reason, no benefit has been shown for hair in the absence of deficiency; the wording “not shown” does not mean that a well-designed study found it ineffective; it also reflects that enough studies have not been done. ^[1]

Does biotin work for brittle nails?

NIH reports three small studies examining biotin in brittle nails; none has a placebo group, and the participants’ baseline biotin status was not reported. In all three, 2.5 mg of biotin per day was used. ^[1]

• Colombo et al. (1990). In a study using scanning electron microscopy, 32 people (10 healthy controls, 22 patients with brittle nails) were examined; in 8 patients with brittle nails (samples before and after biotin), nail thickness increased by 25% (significant according to the authors); in 14 patients whose sample timing did not fully coincide with the biotin period, the increase was 7%. The first author of the study is affiliated with F. Hoffmann-La Roche AG. NIH reports that the 7% increase in the 14 patients sampled after 2–4 months was not statistically significant. ^{[3] [1]}
• Second study. In 45 patients with brittle and thin fingernails, after a mean of 5.5 months of biotin, the nails were found harder and sturdier in 41 patients (91%). ^[1]
• Third (retrospective) study. Clinical improvement was seen in 22 of 35 patients (63%) with brittle nails; biotin had been given for 6–15 months. ^[1]

Because there is no placebo group, these studies cannot attribute the improvement to biotin; for this reason, the evidence is rated “weak.” There are no nail studies in people with healthy nails.

Is high-dose biotin a treatment for multiple sclerosis?

SPI2 is a phase 3 trial examining the effect of drug-level high-dose biotin (MD1003, 100 mg three times daily) in progressive MS. At 90 centers in 13 countries, 642 people aged 18–65 with a diagnosis of primary or secondary progressive MS were randomly assigned to the drug (n=326) or placebo (n=316) group. On the primary endpoint (improvement on EDSS or the timed 25-foot walk (TW25) at month 12; confirmation at month 15), there was improvement of 12% (39 people) in the drug group and 9% (29 people) in the placebo group; OR 1.35 (95% CI 0.81–2.26). The authors concluded that MD1003 could not be recommended for progressive MS because it did not significantly improve disability or walking speed and gave false results in tests that use biotinylated antibodies. The study was funded by the drug’s manufacturer, MedDay Pharmaceuticals; the earlier, smaller MS-SPI study had reported improvement in disability. The result was obtained in progressive MS and at a drug dose far higher than daily supplements; it does not report a separate result for relapsing-remitting MS or low doses, and it also presents no data that low doses are beneficial. ^[4]

Does biotin affect blood sugar or cholesterol?

The systematic review and meta-analysis by Zhang and colleagues covered five randomized controlled trials (445 participants) examining biotin in patients with type 2 diabetes; biotin had been given for 28–90 days. The mean difference in fasting glucose was −1.21 mmol/L, but the 95% confidence interval was between −2.73 and 0.31, including zero. The difference was −0.22 mmol/L (−0.25 to −0.19) for total cholesterol and −0.59 mmol/L (−1.21 to 0.03; includes zero) for triglycerides; there was no significant benefit for insulin; no conclusion could be drawn for HbA1c, LDL, HDL and VLDL. Although the authors wrote in their abstract that fasting glucose, total cholesterol and triglycerides “fell significantly,” the confidence intervals they gave for fasting glucose and triglycerides include zero; only the small fall in total cholesterol has an interval that does not include zero. The authors also noted that more studies are needed. The data cover only people with type 2 diabetes; they do not represent healthy people or diabetes treatment. ^[5]

How does biotin supplementation affect blood tests?

This heading is not a “benefit” but a consequence of supplements, and it may be the most important for decision-making. In the study by Li and colleagues, 6 healthy adults (2 women, 4 men) took 10 mg of biotin per day for 7 days; according to the study, this dose is common in over-the-counter supplements. Interference was found in 9 of 23 tests with biotin-streptavidin components (39%) and in none of 14 tests without these components. Of competitive immunoassays, 5/8 gave falsely high results, and of sandwich immunoassays, 4/15 gave falsely low results. The study is a small, non-randomized preliminary study; a correction of the paper was published in 2017. ^[6]

The FDA’s troponin page states that biotin can significantly distort some laboratory tests and that this may go unnoticed. The FDA reports that it continues to receive adverse event reports of falsely low troponin results due to biotin interference; that some manufacturers have succeeded in reducing interference in their tests and some have not yet. Citing the FDA, NIH reports that a patient taking a high amount of biotin died after a falsely low troponin result on a test susceptible to interference. According to NIH, the FDA recommends that health care workers ask patients whether they take supplements containing biotin and consider biotin interference as a possible source of error if results do not fit the clinical picture. ^{[7] [1]}

Summary table

This guide does not recommend a personal dose; if there is a test plan, pregnancy or chronic disease, the decision is made with a physician.