Hair loss is one of the most upsetting side effects of cancer treatment, and many patients look for ways to bring their hair back. One option that has gained popularity is biotin, a vitamin commonly promoted for stronger hair and nails. But experts say the benefits are uncertain, and the risks may be overlooked. There is little scientific evidence that oral biotin helps hair or nail growth in people undergoing or recovering from cancer treatment. More concerning, it may interfere with medical testing, according to Brittany Dulmage, MD, an oncodermatologist at The Ohio State University Comprehensive Cancer Center -- Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. Biotin, also known as vitamin B7, helps the body produce proteins such as keratin, which supports hair, skin and nails. However, true biotin deficiency is uncommon because the vitamin is widely found in foods like fruits, vegetables, meats, eggs and dairy products.…