New study shows that grapefruit juice could help patients avoid side effects associated with high doses of anti-cancer drug. Photo courtesy Shutterstock.

A daily glass of grapefruit juice more than triples the benefit of taking an anti-cancer drug by itself, according to a new clinical trial funded by the National Institutes of Health. The combination could help patients avoid side effects associated with high doses of the drug and reduce the cost of the medication.

The preliminary study, published in Clinical Cancer Research, shows that eight ounces of grapefruit juice a day can slow the body’s metabolism of a drug called sirolimus, which has been approved for transplant patients but may also help many people with cancer.

“Grapefruit juice, and drugs with a similar mechanism, can significantly increase blood levels of many drugs,” says study director Ezra Cohen, MD, a cancer specialist at The University of Chicago Medicine, “but this has long been considered an overdose hazard. Instead, we wanted to see if grapefruit juice can be used in a controlled fashion to increase the availability and efficacy of sirolimus.”

Grapefruit juice’s pharmaceutical prowess stems from its ability to block intestinal enzymes that break down sirolimus and several other drugs (ask your doc and pharmacist if your pills interact with the juice). In Dr. Cohen’s study, participants who drank eight ounces of grapefruit juice a day increased their sirolimus levels by 350 percent.

“This is the first cancer study to harness this drug-food interaction,” the authors note.

Levels of sirolimus-inactivating enzymes in the body can vary, so testing the amount a patient produces may help predict his or her response to grapefruit juice. However, the ingredients found in grapefruit juices may vary even more than patients’ enzyme levels, Dr. Cohen says.

An early version of the study used canned grapefruit juice, generously donated by a Chicago-based grocery chain. But tests of the product found it lacked the necessary active ingredients. So the researchers shifted to a frozen concentrate product supplied by the Florida Department of Citrus. Further research is needed to confirm the promising findings.

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Earlier research suggests that fish oil—which contains omega-3 fatty acids such as eicosapentaenoic acid—may help patients maintain or gain muscle. To test the hypothesis, a research team led by Vera Mazurak, PhD, of the University of Alberta in Edmonton, Canada, compared the effects of fish oil with that of standard care (no intervention) on weight, muscle, and fat tissue in people newly diagnosed with non-small cell lung cancer.

In the trial, 16 patients took fish oil (2.2 grams of eicosapentaenoic acid/day) during initial chemotherapy treatments which lasted about ten weeks and 24 patients did not.

Data show that patients not taking fish oil lost an average of 2.3 kilograms (5 pounds, 1.13 ounces) whereas patients receiving fish oil maintained their weight. Sixty-nine percent of patients in the fish oil group gained or maintained muscle mass. In contrast, 29 percent of patients in the standard care group maintained muscle mass, and overall, patients in this group lost 1 kilogram (2 pounds, 3.27 ounces) of muscle. No difference in total fat tissue was observed between the two groups.

“Fish oil may prevent loss of weight and muscle by interfering with some of the pathways that are altered in advanced cancer,” said Dr. Mazurak. “This holds great promise because currently there is no effective treatment for cancer-related malnutrition,” she added.

In addition, the investigators think that fish oil may be beneficial to patients with other forms of cancer and chronic diseases that are associated with malnutrition, as well as to elderly individuals who are at risk for muscle loss.

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Article Source: “Nutritional intervention with fish oil provides a benefit over standard of care on weight and skeletal muscle mass in non-small cell lung cancer patients receiving chemotherapy.” Rachel A. Murphy, Marina Mourtzakis, Quincy S.C. Chu, Vickie E. Baracos, Tony Reiman, and Vera C. Mazurak,. CANCER; Published Online: February 28, 2011 (DOI: 10.1002/cncr.25709).

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