Looking Good—Grapefruit Juice Warrants Another Look
Do you like grapefruit juice? Every now and then, grapefruit juice seems to cycle back into fashion as a weight-loss food. It usually feels like yet another fad diet, destined to fizzle out like any other of a number of extreme diets that feature a specific food that’s supposed to promote weight loss.
But grapefruit may deserve another look.
New research shows that grapefruit juice was able to prevent weight gain in mice that were fed a high-fat diet. Remarkably, mice gained less weight when they drank grapefruit juice plus a high-fat diet, as opposed to mice that drank only water while eating the same diet. Essentially, although their diets were otherwise the same, grapefruit-drinking mice gained 18% less weight. There’s no reason to think the weight-gain-suppression effect won’t also work in people.
Investigators at the University of California-Berkeley were so surprised by the results, they rechecked and recalibrated their instruments, then ran everything again. It was no mistake. Something in grapefruit juice was putting the brakes on weight gain. “We see all sorts of scams about nutrition,” said researcher Joseph Napoli, “But these results, based on controlled experiments, warrant further study of the potential health-promoting properties of grapefruit juice.”
To ensure that all other factors were equal, scientists put extra glucose (sugar) in the water of control mice that were drinking only water. This meant that there were no differences in the calories being consumed overall among the different groups of mice. One group of mice even received metformin, a generic drug commonly used to help diabetic patients maintain healthy blood sugar levels.
“The grapefruit juice lowered blood glucose to the same degree as metformin,” said Napoli, professor and chair of nutritional sciences and toxicology. “That means a natural fruit drink lowered glucose levels as effectively as a prescription drug.”
Investigators note that there are numerous compounds in grapefruit juice. One, called naringin, appears to regulate blood sugar levels. But some other compound or compounds must also be at work. “There are many active compounds in grapefruit juice, and we don’t always understand how all those compounds work,” said researcher Andreas Stahl.
Chudnovskiy R, Thompson A, et al. Consumption of clarified grapefruit juice ameliorates high-fat diet induced insulin resistance and weight gain in mice.PLoS One. 2014 Oct 8;9(10):e108408. doi: 10.1371/journal.pone.0108408. eCollection 2014.