Investigators with Beth Israel Deaconess Medical Center (BIDMC) have for the first time identified a hormone that, when stimulated by fructose ingestion, could serve as the basis for a reliable fructose-tolerance test. Jody Dushay, et al., “Fructose ingestion acutely stimulates circulating FGF21 levels in humans,” Molecular Metabolism, October 2014. Known as Fibroblast Growth Factor 21 (FGF21), the hormone in question has been associated with obesity, insulin resistance and non-alcoholic fatty liver disease in both humans and animals. In this study, researchers reported that FGF21 levels increased by an average of 400 percent in healthy volunteers who consumed 75 grams of fructose. By comparison, the consumption of glucose had little immediate effect on FGF21 blood levels.

“This tells us that fructose actively regulates FGF21 in humans,” explained one study author. “The hormone-like response of FGF21 to fructose ingestion suggests that FGF21 might play an unanticipated role in regulating fructose metabolism. We were totally surprised by this dramatic effect because, to date, there has been no way of assessing the body’s acute metabolic response to fructose ingestion. We haven’t had a simple quick test like we have for glucose.” See BIDMC Press Release and The New York Times, October 13, 2014.