GRAPEFRUIT: HEALTH IMPLICATIONS
DR .S. M. ALAM
Sep 26 - Oct 2, 2011
Grapefruit is believed to be native to Jamaica. It is common in Pakistan and other countries of the world. The grapefruit tree can grow to a height of 26 to 30 feet.
Grapefruits are round, with a diameter of between 4 and 6 inches. Their thin skin may be either completely yellow or yellow with a pinkish hue.
The pulp of the fruit may be yellow, pinkish, or reddish. It can be more or less sharp tasting, acidic, sweet, and fragrant. The United States is the largest producer of grapefruit, accounting for over 40 per cent of global production. Approximately, 60 per cent of the grapefruit crop is used for the manufacture of juice and canned grapefruit, while the rest is sold fresh.
The nutritional value of the grapefruit varies with the color (white, pink, or red). Red and pink grapefruits have a higher amount of vitamin A. The most popular varieties cultivated today are red.
Half a grapefruit provides more than 50 percent of the adult recommended dietary allowance (RDA) of vitamin C; it also has 325mg of potassium, 25mcg (micrograms) of folate, 40mg of calcium, and l mg of iron.
The pink and red varieties are high in beta carotene, an antioxidant that the body converts to vitamin A. A cup of unsweetened grapefruit juice has 95mg of vitamin C, more than 150 percent of the RDA, and most of the other nutrients found in the fresh fruit.
Grapefruit stimulates the appetite and is used for its digestive, stomachic, antiseptic, tonic, and diuretic qualities. Grapefruits are especially high in pectin, a soluble fiber that helps lower blood cholesterol.
Recent studies indicate that grapefruits contain substances that are useful in preventing several diseases. Pink and red grapefruits are high in lycopene, an antioxidant that appears to lower the risk of prostate cancer.
Since grapefruit juice is known to inhibit enzymes necessary for the clearance of some drugs and hormones, some have hypothesized that grapefruit juice may play an indirect role in the development of hormone-dependent cancers. A 2007 study found a correlation between eating a quarter of grapefruit daily and a 30 per cent increase in risk for breast cancer.
Researchers have not yet identified lycopene's mechanism of action, but a 6-year Harvard study involving 48,000 doctors and other health professionals has linked 10 servings of lycopene-rich foods a week with a 50 percent reduction in prostate cancer.
Other protective plant chemicals found in grapefruits include phenolic acid, which inhibits the formation of cancer-causing nitrosamines; limonoids, terpenes, and monoterpenes, which induce the production of enzymes that help prevent cancer; and bioflavonoids, which inhibit the action of hormones that promote tumor growth.
Some people with rheumatoid arthritis, lupus, and other inflammatory disorders find that eating grapefruit daily seems to alleviate their symptoms.
Grapefruit achieves its best quality under conditions of hot days and warm to hot nights, which results in higher sugars and lower acids than grapefruit produced in the cooler night temperatures common in Arizona and California.
It grows well in both tropical and subtropical climates of the world, but it is a little less cold hardy than oranges. Grapefruit trees on sour orange rootstock are well-adapted to deep, well-drained soils.
Loamy soils are preferred while heavy clays and poorly-drained soils will result in poor growth and production as well as shorter life.
For maximum cold protection, grapefruit in the home landscape should be planted on the south or southeast side of the house. Distance from the house or other buildings and driveways or walkways should be at least 12 feet to allow adequate room for the tree to grow to its mature size.
While large, overhanging shade trees provides some cold protection. Grapefruit grows and produces best in full sun.
Some grapefruit trees are grown entirely in an artificial, soilless medium, which requires special treatment at transplanting. After the planting hole is ready, remove the tree from the container and use a gentle stream of water from the garden hose to wash an inch or so of the medium from all around the root ball, thereby exposing the peripheral roots. Thus, the outer roots are placed in contact with the soil of the planting site and growth commences almost immediately. Under no circumstances should soil around the proposed planting site be removed to form a shallow basin for watering to do so almost guarantees that the young grapefruit tree will contract foot rot and die before its fifth year. The soil in the planting site should be at least as high as the surrounding yard, if not higher.
To facilitate watering, bring soil from the garden or elsewhere to construct a watering ring atop the ground around the newly planted tree.
The ring should be about two feet across and several inches high and thick. To water, just fill the water ring immediately after planting. After the water soaks in, it may be necessary to add a little soil to any holes formed as the soil settled around the roots. The watering interval should be every few days for the first couple of weeks, then gradually increased to 7 to 10 days over the next couple of months.
The watering ring will gradually melt into the surrounding soil, at which time the young grapefruit tree can be considered to be established. Fertilizer should be withheld until after growth commences.
During the first year, a single cupful of ammonium sulfate (21-0-0) split into three or four applications is adequate. Use two cups in the second year and three in the third.
Budded grapefruit trees, if properly established and grown, should bear in the third season after transplanting. Any fruit that sets in the first and second years should be removed in order to direct all of the young tree's energy into growth. The first production could easily exceed 25 pounds per tree, which should increase to some 250 pounds or more by the tenth season.
The longer the fruit remains on tree, the larger it becomes and the sweeter it becomes. Grapefruit holds very well on the tree, so fruit can be harvested as needed from late October through May. Grapefruit is primarily eaten fresh but it is readily processed as well. The juice can be extracted and chilled for use within a couple of weeks; it can also be frozen for later use.
Grapefruits, however, are a good food to include in a sensible weight-loss diet; a serving contains less than 100 calories, and its high-fiber content satisfies hunger. If you're trying to lose weight, make grapefruit your first course to help prevent overeating. It's also an ideal snack food.
Grapefruits are especially high in pectin, a soluble fiber that helps lower blood cholesterol. Recent studies indicate that grapefruits contain substances that are useful in preventing several diseases. People who are allergic to citrus fruits are likely to react to grapefruits, too. The sensitivity may be to the fruit itself or to oil in the peel.