Irisin, a hormone linked to the positive benefits of exercise, was recently questioned to exist in humans. Two recent studies pointed to possible flaws in the methods used to identify irisin, with commercially available antibodies. In Cell Metabolism, the Harvard scientists who discovered irisin address this contentious issue by showing that human irisin circulates in the blood at nanogram levels and increases during exercise.
Senior study author Bruce Spiegelman of Dana-Farber Cancer Institute and Harvard Medical School says that the confusion over irisin comes down to disagreement over how irisin protein is made in skeletal muscle cells and the detection limits of protocols.
