High fat diet? Maybe you should drink some grapefruit juice

Grapefruit juice may help combat the negative effects of a high-fat diet, say researchers from The University of California-Berkeley, but the exact compound responsible for this remains a mystery.

According to a recent study published in the journal PLoS One, experts were curious if there was any validation to a popular Hollywood fad diet centered on grapefruit juice. To see exactly how this food product affects the body’s metabolism, a group of mice were given clarified, pulp-free grapefruit juice diluted with water for a period of 100 days. The mice were then fed a high-fat diet designed to promote weight gain, and compared to a control group of mice also eating a high-fat diet but only drinking a sweetened form of water.

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Both sets of mice were administered water or grapefruit juice sweetened to be identical in caloric intake.

After 100 days, mice fed a high-fat diet that drank grapefruit juice gained 18 percent less weight compared to the mice on a high-fat diet that drank water. In addition to greater weight loss, grapefruit-drinking mice fed a high-fat diet also showed a 13-17 percent reduction in blood glucose levels and a three-fold reduction in insulin levels.

“Relatively few human studies have examined the effects of grapefruit or grapefruit juice consumption per se on metabolism in well-controlled experiments, and these have produced intriguing but contradictory results,” wrote researchers in the report. “We have provided new evidence for potential health-promoting properties of grapefruit juice in murine high-fat diet-driven obesity and non-obesity models. These results justify additional studies in animal models and humans to assess the mechanisms and scope of grapefruit juice action.”

What researchers couldn’t determine, however, was exactly why the mice drinking grapefruit juice lost more weight; while there is a compound in grapefruit juice– naringin–previously linked to weight loss, when researchers isolated the compound and fed it to the mice exclusively, no weight loss was seen. This suggests another compound in the juice was responsible, but the naringin was shown to lower glucose levels in the mice as effectively as some prescription medications.

“There are many active compounds in grapefruit juice, and we don’t always understand how all those compounds work,” lead researcher, Andreas Stahl, told MNT. “Basically, we couldn’t see a smoking gun that could explain why or how grapefruit juice affects weight gain.”

While the new data shows there may be some medical applications for adding grapefruit juice to a diet, individuals should consult with their doctors ahead of time. Grapefruit is known to interfere with more than 80 prescription medications, causing everything from kidney damage and muscle breakdown to death. As little as eight ounces of grapefruit juice or a single grapefruit is enough to cause a severe adverse interaction within a 24-hour period.

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“People know that drugs react with drugs, but fewer are aware of drug-food interactions,” said to ABC News Professor Paul Doering of the University of Florida Pharmacy Department. “Health professionals need to learn as much as they can about this.  Undetected there are very serious adverse effects.”

It should also be noted that mice fed a low-fat diet during the research did not see any weight loss benefits, meaning grapefruit juice diets are still considered fad diets only. Only mice consuming high-fat diets saw grapefruit juice-related changes.