What You Need to Know if You Take Biotin (Vitamin B7)

Updated July 2026

Maybe you've flipped through a magazine and seen ads claiming that taking extra biotin, also known as vitamin B7, will give you lustrous hair, glowing skin, and perfect nails. Before you stock up, there's something more important you should know: biotin can interfere with common medical tests, including the one used to diagnose a heart attack.

Why can biotin be a problem?

Because it can throw off important blood tests. The FDA has warned that biotin can interfere with troponin, the key blood test for diagnosing a heart attack. In biotin users, that interference can cause a falsely normal result, which means a heart attack could be missed at the worst possible moment. High doses can also distort thyroid function tests. This isn't brand-new: the FDA first flagged it in 2017, and while some lab makers have since adjusted their tests to reduce interference, many labs remain vulnerable, and it's not even clear that skipping the supplement before a test fully solves the problem.

How much biotin do you actually need?

Far less than supplements provide. The recommended daily intake is about 30 micrograms, and most people get plenty from food alone. Many hair and nail supplements deliver up to 5,000 micrograms, more than 150 times what's considered necessary. If you take anything marketed for hair, skin, or nails, check the fine print, because biotin isn't always obvious on the label, and it also turns up in many multivitamins and prenatal vitamins.

Isn't this just another supplement concern?

Yes, and that's rather the point. Because supplements aren't regulated by the FDA the way medications are, and because you don't need a prescription, it's easy to forget they can have real, sometimes unintended, effects on your body. I've written before about how people worldwide spend more than $130 billion a year on supplements, over $35 billion in the US alone, despite little evidence that most of them deliver any health benefit. Most aren't harmful, but the biotin story shows they aren't automatically harmless either. That's why anyone who takes supplements should keep a list of exactly what they take, and the doses, and share it with every health care provider, especially in an emergency.

Which foods contain biotin?

Plenty of everyday ones. If you want to be sure you're getting enough, include nuts, seeds, avocados, cauliflower, sweet potatoes, and salmon in your diet. Nutritional yeast is another good source, as are egg yolks and beef liver, though those last two are worth limiting for other reasons.

And if it's your heart you're concerned about, stop looking in the supplement aisle and take stock of your diet instead. The science is clear that optimizing what you eat is the real secret to better health. Try swapping two of your daily snacks for our products, and you may be pleasantly surprised at your next lab visit.

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