Grapefruit can Cause Unintended Effects

Grapefruit is a wonderfully healthy food, providing people with a rich source of vitamin C. However, compounds found in this fruit that can lead to potentially serious outcomes.

A recent consumer update press release from the FDA warns that compounds found in fresh grapefruit and grapefruit juice can act on an enzyme found in the intestines. This enzyme is an integral part of drug metabolism and can lead to potentially hazardous effects when combined with certain pharmaceutical and over-the-counter drugs..

If this enzyme cannot do its job properly, taking certain drugs can lead to toxicity because too much of the drug will enter the body.

The compounds in question are two chemicals in the class called furanocoumarins. One is the compound bergamottin, the other is a related compound called dihydroxybergamottin. These compounds prevent an enzyme called CYP3A4 from performing its proper function in digestion.

One of the jobs of CYP3A4 is to help the body process certain drugs. If the grapefruit compounds interfere with its ability to do its job, some of drugs you may be taking will not be broken down at the usual rate.

When manufacturers set the amounts of drug dosages, they are taking into account what CYP3A4 will be doing. If CYP3A4 is not working right, it may be possible for the person to end up with toxic levels of the drugs in their blood stream.

Grapefruit Juice and Medication Can Be a Dangerous Mix Grapefruit juice can be dangerous for people on certain medications, nurse researchers remind doctors, nurses, and everyone who takes medicine and enjoys grapefruit juice, in a paper in the American Journal of Nursing, a journal of the American Nurses Association.

Amy Karch, R.N., M.S., of the School of Nursing at the University of Rochester Medical Center reported on a man from a northern climate who moved to Florida for the winter – one of tens of thousands of “snowbirds” who head south each winter – and began drinking two to three glasses of grapefruit juice each day. The man became critically ill as a result of an interaction between grapefruit juice and his cholesterol-lowering medication.

Karch’s paper, “The Grapefruit Challenge: The juice inhibits a crucial enzyme, with possibly fatal consequences,” appears in the December 2004 issue of the journal.

Interactions between grapefruit juice and medications have long been recognized. Last year, the Medical Letter on Drugs and Therapeutics devoted an entire issue to grapefruit juice and the dangerous drug interactions that can result. The U.S. Food & Drug Administration requires all prospective new drugs that are thought to interact with this enzyme system to be tested for interactions with grapefruit juice. And a warning about grapefruit juice is included in the “food-drug interactions” that come with dozens of medications. Nevertheless, Karch says many health-care professionals and patients don’t know about the risk.