Fruit at Fault?

Should you accept grapefruit from someone who has had a bumper crop this year? Maybe not.

For more than 20 years, we have known that certain medications interact with an enzyme found in grapefruit—but the number of drugs with that potential has jumped to more than 85. There is not only an overdose hazard with this food-drug combination, but also the possibility for serious adverse drug reactions.

Actually, there has been a disturbing trend in the last four years, as the number of drugs with potential interactions with grapefruit has increased fourfold. With some medications, taking one tablet with a glass of grapefruit juice can be like taking 20 tablets. Many of the drugs are common—such as cholesterol-lowering statins—but the list also includes certain antibiotics like erythromycin, as well as calcium channel blockers used to treat hypertension. Others include agents used to fight cancer or suppress the immune system in people who have received an organ transplant. Of the 85 known drugs that interact with grapefruit, 43 can have serious side effects, including sudden death, acute kidney failure, respiratory failure, gastrointestinal bleeding and bone marrow suppression in people with weakened immune systems.

Researchers say that the most at-risk people are older than 45, since they are most likely to be taking prescription medications. Coincidently, the people I know with the oldest and largest grapefruit trees are also over the age of 45. So, if you fit the demographic, make sure both your doctor and pharmacist are aware of all of your medications, even those purchased over the counter. Include in that list any herbs or home remedies you may take, since some, like red yeast rice, have similar statins to commercial drugs.

Citrus fruits contain active ingredients called furanocoumarins that irreversibly block the drug-metabolizing enzyme called cytochrome P450 3A4. That’s the technical scoop. Maybe I am sounding overly cautious on this one, but other citrus fruits—Seville oranges (often used in marmalade), limes and pomelos—can lead to drug interactions, too. These are the citrus fruits that have been researched. What about satsumas, Louisiana sweets, navels? Do we know? I’m not blaming the fruit …

Be proactive. For a list of generic drugs with possible interactions with grapefruit, click here.

Debbie Melvin, M.S., C.F.C.S., is an extension agent for the LSU AgCenter. She specializes in nutrition and knows just about everything there is to know about everyday living.