Grapefruit. Risky food?

Philip J. Goscienski, M.D.

April 2010

A few years ago the Grapefruit Diet was popular but there have been warnings that grapefruit and grapefruit juice put some persons at risk if they are taking certain medications. Grapefruit-drug interactions are not to be taken lightly.

Like any fruit, the grapefruit, which has been a popular favorite for more than century, has genuine health benefits. High in fiber, vitamin C and antioxidants such as lycopene, this citrus is a great addition to the diet. Fruits and vegetables lower the risk of several cancers and help to prevent heart disease and stroke. If that's not enough, a diet that is high in fruits and vegetables delays the onset of dementia. Yet barely one-fifth of Americans take in the recommended minimum of 5 servings of fruits and vegetables a day and even fewer of us get the optimum of 10 or 11 on a consistent basis.

About 20 years ago an astute Canadian pharmacologist observed that when patients drank grapefruit juice within a short time of taking their blood pressure medication the absorption of the drug increased nearly three-fold. It didn't take long before the medical community realized that this occurred with several other prescription medications and in some cases the outcome was serious, even fatal.

The body reacts to many drugs as if they were toxic chemicals and it calls upon defense mechanisms that have evolved over hundreds of thousands of years to detoxify these chemicals. The specific mechanism by which grapefruit juice or the fruit itself produce high blood levels of some medications is the blocking of certain enzymes in the lining of the intestinal tract and the liver. This is a complex process and we are far from understanding it completely. For instance, not everyone reacts the same way to grapefruit, and grapefruit is not the only citrus product that causes this interference with the body's ability to detoxify drugs.

Medications that are useful in lowering cholesterol, treating heart disease and reducing blood pressure are among the many that are affected. In fact, more than half of the prescription drugs that are taken by mouth can reach excessive levels in the blood and it doesn't help to separate the taking of the drug and that morning drink of grapefruit juice by a few hours. The safest route is to have your physician as well your pharmacist verify that it's alright to eat or drink citrus products during treatment.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at