A Discussion of Its Nutritional and Medical Benefits
Large citrus fruit with a bitter yellow or pinkrind and inner skin, and with highly flavorful somewhat acidic pulp; from an evergreen or semi-evergreen tree (Citrus paradisi). A valuable source of nutrients, the grapefruit -- along with its cousin ugli fruit (Citrus tangelo), a cross between the grapefruit and the tangerine -- are beloved for their striking, tart taste and juicy pulp. The following discussion will focus on its often overlooked nutritional and medical benefits. Please note that the ingestion of grapefruit may conflict with a number of drugs; see Medical Indications below.
Purchase and Storage
To locate particularly juicy grapefruit, search for firm fruit that seems heavy for its size. A slightly greenish tint does not indicate under-ripeness; instead, it means the fruit will be high in sugar content. Most grapefruit, however, have a yellow skin that should be thin, smooth, and fine-grained. Ugli Fruit gives the impression of being rotten (misshapen, splotched) though they are pleasant in taste, usually mellower in fragrance than a grapefruit. Avoid puffy skin, or a lower weight than would be expected for its size: it is most likely dry inside.
Grapefruit is, expectedly, best stored at room temperature for a maximum of one week. Grapefruit juice may be refrigerated in a tightly closed glass bottle with very little air space at the top. By storing it this way, oxygen is not permitted to penetrate the fruit; oxygen destroys vitamin C content. Most plastic bottles are oxygen-permeable. Grapefruit juice can hold its vitamin C content for several weeks when properly stored and refrigerated.
Commerical Grapefruit Juice
Vitamin C being the most readily available nutrient in the grapefruit, its preservation during commercial preparation is of utmost importance. Commercial flash-freezing preserves up to 95% of the vitamin C in fresh grapefruit juice. Canned juice will lose, on the average, only 2% of its vitamin C, while cartons of prepared, pasteurized juice lose up to 20% because they are sold in plastic or waxed-paper cartons that allow oxygen flow.
Commercial pasteurization is a process which halts the conversion of sugar to alcohol; it protects juices from harmful bacteria and mold contamination. Since 2000, following several deaths attributed to unpasteurized juice containing E. Coli (O157:H7), the FDA requires that all vegetable and fruit juices be pasteurized.
Medical Use and Benefits
Lowering the rise of heart attack.
When researchers at the University of North Carolina (Chapel Hill, 1997) attempted to confirm evidence that beta-carotene (antioxidant pigment found in fruits and vegetables) lowers heart attack risk, EURAMIC data confirmed that indeed lycopene was the protective agent. Lycopene works in coordination with polyunsaturated fats. Though all fruit carries some amount of lycopene, grapefruit has the highest concentration among citrus fruit. According to the Chapel Hill study, its benefit is most apparent among people whose body composition was more than 16% in polyunsaturated fat.
Prevention of some cancers.
Grapefruit contains a substance called D-limonene - a monoterpene, aromatic compound found in citric oil - that reduces the risk of cancer by: preventing the formation of carcinogens in the body; blocking cancer-causing substances from reaching or reacting with sensitive body tissue; and by inhibiting the transformation of healthy cells to malignant ones.
Healing of Wounds
The body requires that vitamin C be present to convert amino acid proline into hydroxyproline (component of collagen) which forms skin, tendons, and bones. A healthy amount of hydroxyprolin, then, prevents and remedies the illness scurvy - the result of inadequate amount of vitamin C - and allows the body to more easily heal its wounds.
Additionally, grapefruit drastically improves the body's ability to absorb iron; this is helpful for the elderly whose diet may require the ingestion of iron supplements.
Consumption of grapefruit or grapefruit juice has been shown to conflict with the following medications:
- Aspirin or other anti-inflammatory drugs (NSAIDS) such as ibuprofen, naproxen, and others. Citrus fruit may intensify the drug's ability to irritate the stomach and cause gastric bleeding.
- Antihistamines (used for treating cold symptoms and allergic reactions such as hay fever), anticoagulants, benzodiazepines (tranquilizers, sleep medications), calcium channel blockers (blood pressure medication), cyclosporine (immunosuppressant drug used in organ transplants), theophylline (asthma medication).
- The consumption of grapefruit (juice) appears to reduce the amount of these drugs that the body can metabolize and eliminate.
- While it is not yet known (1999) what chemical in grapefruit is responsible for this conflict, a strong possibility is bergamottin, a naturally occuring chemical known to inactivate cytochrome P450 3A4, which, as a digestive enzyme, converts many drugs to water-soluable substances which can be flushed out by the body.
Grapefruit is delicious when broiled or poached - especially for festive occasions, such as Thanksgiving or holiday feasts - and served with a moderate amount of brandy or wine in the fruit, and topped with a cherry.
Energy value (calories per serving): low
Saturated fat: low
Fiber: moderate to high
Major vitamin contribution: vitamin A, vitamin C
Major mineral contribution: Potassium
Kohlmeier, Leonard; et. al. "Lycopene: The New Heart Attack Preventer". American Journal of Epidemiology. October, 1997.
Rinzler, Carol Ann. The New Complete Book Of Food: A Nutritional, Medical, and Culinary Guide. New York: Checkmark Books, 1999.