Biotin for Hair Growth

Biotin for Hair Growth is a classic example of marketing over science: biotin deficiency affects only 1 in 100,000 people, yet sales top $500 million annually. A randomized trial published in Skin Appendage Disorders found that 2.5 mg of biotin daily for 90 days produced no measurable increase in hair thickness or growth rate in women with thinning hair. For the 99.999% of users with normal levels, the vitamin is simply excreted unchanged in urine—a waste of $20 per bottle. In fact, a 2017 meta-analysis showed biotin supplements are 40% less effective than demonstrating no effect at all, since they can also interfere with lab tests for thyroid and cardiac markers.