close Peptides can be useful, but some people may be moving too fast, expert warns New York fitness trainer and gym owner Kenny Santucci discusses concerns about unverified peptide products for muscle building, saying consumers should work with physicians. NEW You can now listen to Fox News articles! Americans are popping more supplements – and fewer multivitamins – than ever before, a new study found. Research published in JAMA Network Open, led by researchers at Memorial Sloan Kettering