You may have noticed something new the last time you shopped online or visited the supplements section of your drugstore – many supplements offering 'longer hair and thicker nails.” At the center of this recent trend is biotin, a B-complex vitamin (also called vitamin B7) that plays an important role in cell growth and food metabolism. However, at higher doses, biotin could be throwing off a number of lab test results, including those for thyroid disease and heart attack. In the past few years, many vitamins and supplements have emerged promising to deliver the best hair, skin and nails of your life in just one nutrient-filled bite. These supplements are loaded with what some believe are good-for-your-hair-and-nails ingredients, including one of the B-complex vitamins – biotin. Like the rest of the B-complex vitamins biotin plays an important role in cell growth and food metabolism. Between diet and supplements, the Institute of Medicine recommends that people 19 years and older get 30 micrograms (mcg) of biotin daily.1 Most people get the biotin they need from eating a healthy diet, but there’s growing evidence that suggests that biotin supplements may help regulate your blood sugar, promote healthy hair, skin and nails, and help pregnant moms have healthier babies. Biotin is also being recommended in higher doses by some doctors for conditions such as some cancers, diabetes, dermatitis and multiple sclerosis. Many biotin dietary supplements—as well as when doctors prescribe it for health conditions—contain biotin levels up to 650 times the recommended daily intake.2,3,4 What You Might Not Know about Biotin If you take vitamins or herbal supplements, you may already know that these products may interact—sometimes harmfully—with other medications. When taking biotin supplements, what you may not realize is that at higher doses, they can also affect the results of some important lab tests. Many tests employ technology that uses biotin to generate test results. If you take a biotin supplement, it can produce 'false-positive' or 'false-negative' lab test results, which may lead to misdiagnoses or unnecessary treatments for heart disease, thyroid conditions, breast cancer, pregnancy and fertility. The good news is that not all lab tests are affected by biotin. Current Abbott lab tests are designed in a way that biotin doesn't affect the test results.