This article was originally posted in the Montreal Gazette.
Despite popular belief to the contrary, I don’t hate vitamin and mineral supplements. My main argument against them is that they are largely ineffective, most people do not have vitamin deficiencies, supplements have a non-negligible cost and can pose health risks. Amazingly, though, the health risks are largely unknown to the general public. I would wager despite the findings of The U.S. Preventive Services Task Force, few people know that beta-carotene can increase the risk of cancer in smokers or that vitamin E has been associated with more hemorrhagic strokes. Similarly, I expect few people know of the multiple health warnings issued about the supplement biotin.
Biotin might seem harmless. It’s part of the B-complex of vitamins, formally vitamin B7, and is often marketed as a way to improve the health of skin, hair and nails. It’s true that people with biotin deficiency develop a typical rash around the nose, eyes and mouth. They can also get brittle nails and see their hair thin out. But biotin deficiency is extremely rare. Unless you have a specific genetic mutation, abuse alcohol or eat copious amounts of raw egg whites for some reason, you probably get more than enough biotin in your diet and taking a supplement is unnecessary.
The issue with biotin is not one of toxicity. You likely can’t overdose on biotin because water soluble B-vitamins don’t build up in human tissue. Once you get the required amount, your body excretes the surplus in urine. Hence the common adage that buying vitamin supplements gives you expensive pee.
The danger with biotin is its ability to interfere with common blood tests. Hence the multiple FDA warnings on the issue. Most blood tests are immunoassays, which means they work by having an antibody bind to the molecule of interest. Anything that interferes with this coupling can skew lab results.
A few telling examples have been reported in the literature. A 2016 report in the New England Journal of Medicine described the case of six children who were taking biotin and had abnormal lab results suggestive of Grave’s Disease, a form of hyperthyroidism. But once the biotin was stopped, the results returned to normal in a few days. In this case, the underlying cause was identified, but it is easy to see how spurious lab results could lead to people being prescribed medication for diseases they don’t actually have.
Another more insidious example is biotin’s ability to produce falsely low troponin results. Troponin is a cardiac biomarker that is used to detect heart attacks in people presenting to the emergency room with chest pain. A falsely low troponin result could result in a heart attack being missed or misdiagnosed. Reports of adverse events and one death prompted the 2017 safety communication and the subsequent updates including the one in 2022.
It is important to note that not all test results are affected by biotin and low levels of biotin in the bloodstream may have minimal impacts on these results. Also, manufacturers of certain testing assays have found technical solutions to minimize the problem. But biotin use is becoming more common and U.S. surveys have shown an increasing trend in its use over the past decades. It’s also a common addition in multivitamin products and so most people may not even be aware they are taking it, let alone that it can affect their test results.
There is a simple solution to the problem. Given that excess biotin is quickly excreted from your system, you can stop the supplement for a few days and repeat any suspect blood tests to confirm normality. Of course, since there is no good evidence that biotin prevents any disease or is necessary for the majority of the population, you could just stop it altogether and save your money.
