Grapefruit and Some Drugs Don’t Mix

Grapefruit seems to be the never-ending subject of nutritional hype and speculation. There are at least a dozen or more so-called grapefruit diets touted for fat burning and weight loss.

There is also an expensive pill on the market that is supposed to contain the specific grapefruit enzymes that do this job. (Unfortunately, grapefruit has no secret enzymes to burn fat.)

The latest headlines about grapefruit enzymes concern its interaction with certain prescription medications. Unlike the fat-burning myth, this current round of grapefruit news seems to be true.

Apparently there is a particular substance in grapefruit, not found in most other citrus fruits. It is this substance--which gives grapefruit its sour taste--that affects the way in which certain drugs are metabolized.

This means that drinking grapefruit juice or eating grapefruit while taking these drugs can raise or lower the concentration of the drug in your bloodstream. And this is not a good thing because, in some cases, this increases the risk of side effects and serious reactions, while in others it can mean that you don’t get enough of a drug that you need.

The following drugs are most affected by this interaction:

* Calcium channel blockers (for high blood pressure and angina) such as felodipine (Plendil), nifedipine (Procardia, Adalat), amlodipine (Norvsac), diltiazem (Cardizem, Dilacor) and verapamil (Calan, Verelan).

* Tranquilizers such as benzodiazepines (Halcion).

* Antihistamines such as Seldane and Hismanal.

* AIDS drugs (the protease inhibitor Crixivan).

* Toenail fungus drug (Sporanox).

It is hard to make any general recommendations here because the interaction doesn’t occur in everybody and not with all varieties of grapefruit juice, for some unknown reason. It is most likely to happen if the medication is always, or often, taken with juice. If you drink a lot of grapefruit juice and take any of these medications, it’s a good idea to check it out with your pharmacist or physician.

You may want to switch to a different kind of juice, even though it’s a shame because grapefruit is quite a nutritional bargain. It is very high in vitamin C. In fact, one-half of a medium grapefruit will give you almost 70% of your daily requirements. An 8-ounce glass of fresh-squeezed grapefruit juice will give you more than 150% of the recommended daily allowance (RDA) for vitamin C. Even canned juice and juice made from concentrate will provide 112% and 139%, respectively, of the RDA per 8-ounce serving.