Everyone is talking about biotin supplements. Here’s what you need to know. – USA TODAY

Dr. Michael Daignault| Opinion contributor

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The popular beauty supplement biotin is trending again, but not for the reasons you think.

Concern over biotin's potential interaction with COVID-19 diagnostic tests peaked right about the same time the US government was sending out millions of rapid antigen tests to peoples' homes. The widespread news coverage and interest suggested that a lot of Americans take biotin as a supplement or as part of a daily multivitamin.

So, does taking biotin as a supplement interact with rapidtests? Short answer: Very unlikely. But more on that later.

This spotlight on biotin is a great opportunity to examine whether the scientific evidence supports the many results promised by the beauty industry.

Biotin is part of the essential vitamin B-complex. It helps the body convert food into energy and regulateblood sugar levels. It also plays key role in helping cells function well.

The recommended daily allowance for biotin is 100mcg (0.1mg). The biotin in multivitamins is typically 30mcg, or 0.03mg. This amount is easily obtained from a well-balanced diet. Foods that contain the most biotin include eggs, fish, meat, seeds, nuts, and certain vegetables (such as sweet potatoes). As such, biotin deficiency is a rarely made diagnosis by physicians.

However, it can be quite debilitating for patients. Biotin deficiency presents with multiple symptoms including brittle nails, thinning hairand a scaly red rash around the eyes, nose, mouthand perineum. Some research has shown that high-dose biotin supplementation can help in particular with improving the strength of nails in those with known deficiency. However, the research studies are flimsy when it comes to whether supplementing with biotin will further strengthen or accelerate growth in the hair and nails of healthy people.

The beauty industry extrapolated the results of limited research and a small number of case studies to promote biotin supplements for all matter of applications, including skin, hairand nail growth and quality.

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Their promises appear to be based on three research studies that feature daily supplementation of 2.5mg of biotin - 25 timesthe daily recommended dose in participants with brittle nails. In the most oft-cited study, eightwomen who had their nail samples obtained before and after 6 months of daily biotin supplementation, demonstrated an increase in nail thickness by 25%. A second study of 45 patients showed that 91% of them had firmer and harder fingernails after an average of 5.5 months. A third retrospective study found that 63% of patients had improved nail quality after 6-15 months of treatment.

While all threestudies demonstrate improvement in nail quality in those who had been diagnosed with brittle nails, none included a placebo group for comparison, an important aspect of a randomized-control trial that increases a studys validity and worth. However, what this research does indicate is that biotin supplementation likely helps in patients withknownbiotin deficiency. What these studies don't demonstrate, is what effect biotin supplementation will have in people with normal nails.

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The evidence to support biotin supplementation for improved hair and skin health is even weaker. There exists only a small number of case reports with claims that biotin supplementation promoted hair health or resolved skin rashes and these were only done in children again without a comparable placebo group.Case studies represent a low strength of evidence when it comes to research studies.

The good news? Supplementing with high-dose biotin is unlikely to be toxic (however high doses can cause stomach distress in some individuals). And since biotin is water-soluble, the body does a pretty good job of excreting excess amounts through urination.

Prior to the pandemic, the FDA had cautioned that high doses of biotin could affect the results of blood tests measuring thyroid levels and other hormones, and some heart tests, which we commonly order in the ER to assess for congestive heart failure and heart attacks. Many lab tests use biotin technology due to its ability to bond with specific proteins which can be measured to detect certain health conditions. In theory, if you take a high-dose biotin supplement, it can produce "false-positive" or "false-negative" blood test results.

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COVID-19 rapid antigen and PCR tests are nasal (and sometimes saliva) tests. Its extremely unlikely that theres sufficient biotin in the nose and mouth (if any at all) to alter either a rapid antigen or PCR test. And almost all COVID-19 diagnostic tests, including the ones we were sent in the mail, do not include biotin technology, so theres no need to worry about that potential interaction.

Most people are not biotin deficient given that it is abundant in a variety of food sources. But if you think you are suffering from brittle nails or other symptoms, consult your doctor before self-diagnosing yourself with a biotin deficiency. Any of these ailments alone could be caused by a wide range of conditions that should be addressed before landing on biotin deficiency as the cause. And the current available scientific evidence does not strongly support high-dose supplementation with biotin in healthy individuals for cosmetic purposes, including nail/hair growth and/or strengthening.

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Everyone is talking about biotin supplements. Here's what you need to know. - USA TODAY