In Any Form, Grapefruit Packs a Big Nutritional Punch

Grapefruit has had its share of nutritional hype over the years. Remember the grapefruit diets that were supposed to burn fat? And the wallet-burning grapefruit pills that contained special enzymes to help you lose weight without any dieting or exercise whatsoever?

Unfortunately, these claims were just wishful thinking: Grapefruit has no secret enzymes to burn fat--and neither does any other food.

But there is one story about grapefruit that has turned out to be true and is worth noting: Grapefruit interacts with certain prescription medications.

The unique substance that gives grapefruit its sour taste affects the way certain drugs are metabolized. So drinking grapefruit juice or eating grapefruit while taking these drugs can raise or lower the concentration of the drug in your bloodstream. In some cases, this can increase the risk of side effects and serious reactions; at other times, you may not get enough of a drug that you need.

In the case of statin drugs for lowering cholesterol, a recent study shows that grapefruit juice can boost the levels of the drug in the blood by up to 12 times, which could be dangerous.

The following drugs are most affected by grapefruit:

* 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).

* Lovastatin, simvastatin and other statin drugs for lowering cholesterol.

* Tranquilizers such as benzodiazepines (Halcion).

* Antihistamines such as Seldane and Hismanal.

* An AIDS drug (the protease inhibitor Crixivan).

* Toenail fungus drug (Sporanox).

It is hard to make any general recommendations about such interactions because the problem 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 with your pharmacist.

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You may want to switch to a different kind of juice, even though 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, or RDA, for vitamin C. Even canned juice and juice made from concentrate will provide 112% and 139% of the RDA, respectively, per 8-ounce serving.

Grapefruit also contains a lot of potassium, and the pink and red varieties have some beta carotene. And all of this comes with about 40 calories per half grapefruit.

You can get grapefruit almost all year, but the best time is between January and June. Worldwide, most grapefruit comes from Florida, but some of the newer red varieties are also grown in Texas, Arizona and California, as well as a few places where the weather is usually warm. It is not particularly expensive, especially considering how much you get from one fruit.

When you buy grapefruit, look for those that seem heavy for their size, and are round, smooth and glossy, with slightly flattened ends. This is a pretty good guarantee that they will be juicy. Skin discolorations do not usually affect the quality of the fruit inside.

Grapefruit will keep for six to eight weeks in the crisper of your refrigerator, but you can leave them out at room temperature for about a week with no problem. In fact, you should serve them at room temperature because they will be juicier.

There are many ways to eat grapefruit, but rinse well before cutting into them. If you want to serve a grapefruit half in the shell, cut it across the middle and not from end to end. Then use a sharp knife and cut around the outer edge of the grapefruit, between the skin and the fruit. After this is done, cut between each of the segments and on either side of the “dividers.” Even if grapefruits are advertised as being seedless, you may still find a few seeds, which you can easily remove.

Grapefruit can also be a great portable snack. Simply peel it like an orange. Once you have the skin off, you can pull the segments apart quite easily. Because grapefruit doesn’t have to stay cold, it is great for brown-bag lunches.

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A real treat, especially in the morning, is to prepare the grapefruit halves, then put a little maple syrup or brown sugar on top and stick them under the broiler for a few minutes. Garnish them with a strawberry or a maraschino cherry, and serve them piping hot. You can also try adding some spices like cinnamon, ginger or vanilla extract to jazz them up a bit.

No fruit salad is complete without some grapefruit sections, and for a really attractive and low-calorie dessert, try creating a fruit compote by mixing different-colored varieties and putting them back into an empty grapefruit shell.

If you’re in a Martha Stewart kind of mood, you can scallop the edge of the shell and put some fresh mint sprigs on top.

Grapefruit is also a nice surprise in a green salad and can be used instead of lemon with fish dishes. This is such a healthy fruit that, unless you need to avoid it because of your medications, it is worth experimenting with ways to prepare it.

Dr. Sheldon Margen is professor of public health at UC Berkeley; Dale A. Ogar is managing editor of the UC Berkeley Wellness Letter. They are the authors of several books, including “The Wellness Encyclopedia of Food and Nutrition.” Send questions to Dale Ogar, School of Public Health, UC Berkeley, CA 94720-7360, or e-mail daogar@uclink4.berkeley.edu.