By Doug Ohlemeier, The Packer

Leading citrus growers groups are taking aim at a study that tries to link grapefruit consumption with breast cancer.

The British Journal of Cancer July 10 reported a study that attempted to connect fresh grapefruit consumption with breast cancer risk in post-menopausal women.

Grapefruit defenders call the study inconclusive and scientifically unable to confirm that eating grapefruit causes breast cancer.

The Florida Department of Citrus, Lakeland, is using a coalition of scientific experts through the Chicago-based Golin-Harris International public relations agency to discount the study’s findings. Researchers and others in Texas and California are also involved in the effort.

The study’s authors claimed that women who daily ate a fourth of a grapefruit or more had a 30% greater risk of contracting breast cancer than women who didn’t eat grapefruit.

A molecule called cytochrome P450 3A4 (CYP3A4) helps metabolize or break down estrogen, the hormone associated with the risk of breast cancer. The researchers stated there is evidence that grapefruit, which inhibits CYP3A4, increases plasma estrogen concentration.

“Since it is well established that estrogen is associated with breast cancer risk, it is plausible that regular intake of grapefruit would increase a woman’s risk of breast cancer,” the University of Southern California and the University of Hawaii researchers wrote in the study’s abstract.

The citrus industry-supported researchers are from Harvard, Boston; Texas A&M University, College Station; Ohio State University, Columbus; and the University of Florida, Gainesville.

“Their (the scientists’) findings were only a weak correlation between grapefruit consumption as it was measured and an increased risk for breast cancer,” said Denise Paleothodoros, Golin-Harris’ vice president.

“The findings are in conflict with prior, consistent and highly credible research on the positive health and wellness benefits associated with grapefruit consumption.”

Ray Prewett, president of Texas Citrus Mutual and the executive vice president of the Texas Vegetable Association, Mission, said the study’s conclusions are premature.

“They didn’t actually measure estrogen levels. They didn’t have complete details on those people's diets,” he said.

Dan Richey, chief executive officer of Riverfront Groves LLC, a Vero Beach, Fla.-based grapefruit shipper, said the industry is working to counteract the study.

“Every day there is some kind of scientific study that contradicts an earlier one,” he said. “If you read every one of them, you would never eat or drink anything.”