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  • Delicious, grapefruit is very low in calories, consists of just 42 calories per 100 g. Nonetheless, it is rich in dietary insoluble fiber pectin, which by acting as bulk laxative helps to protect the colon mucous membrane by decreasing exposure time to toxic substances in the colon as well as binding to cancer causing chemicals in the colon.

  • Pectin has also been shown to reduce blood cholesterol levels by decreasing re-absorption of cholesterol binding bile acids in the colon.

  • The fruit contains very good levels of vitamin-A (provides about 1150 IU per 100g), and flvonoid antioxidants such as naringenin, beta-carotene, xanthin and lutein. Studies suggest that these compounds have antioxidant properties and are essential for vision.

  • Vitamin A also required maintaining healthy mucus membranes and skin. Consumption of natural fruits rich in vitamin-A and flavonoids helps to protect from lung and oral cavity cancers.

  • It is a good source of antioxidant vitamin-C; provides about 52% of DRI. Vitamin-C is a powerful natural anti-oxidant and helps body develop resistance against infectious agents and scavenge harmful free radicals; also is required for the maintenance of normal connective tissue as well for wound healing. It also facilitates dietary iron absorption from the intestine.

  • Fresh fruit is very rich in potassium. Potassium is an important component of cell and body fluids, helps controlling heart rate and blood pressure through countering sodium effects.

  • Red varieties of grapefruits are especially rich in the most powerful flavonoid antioxidant, lycopene. Studies have shown that lycopene protects skin damage from UV rays, and offers protection against prostate cancer.

  • It contains moderate levels of B-complex group of vitamins such as folates, riboflavin, pyridoxine, and thiamin in addition to some resourceful minerals such as iron, calcium, copper, and phosphorus.

Principle Nutrient Value Percentage of RDA
Energy 42 Kcal 2.3%
Carbohydrates 10.7 g 8%
Protein 0.77 g 1%
Total Fat 0.14 g <1%
Cholesterol 0 mg 0%
Dietary Fiber 1.70 g 4%
Vitamins

Folates 13 µg 3%
Niacin 0.204 mg 1.5%
Pantothenic acid 0.262 mg 5%
Pyridoxine 0.053 mg 4%
Riboflavin 0.031 mg 2.5%
Thiamin 0.043 mg 4%
Vitamin A 1150 IU 38%
Vitamin C 31.2 mg 52%
Vitamin E 0.13 mg 1%
Vitamin K 0 µg 0%
Electrolytes

Sodium 0 mg 0%
Potassium 135 mg 3%
Minerals

Calcium 22 mg 2%
Copper 0.032 mg 4%
Iron 0.08 mg 1%
Magnesium 9 mg 2%
Manganese 0.022 mg 1%
Phosphorus 18 mg 2.5%
Selenium 0.1 µg 0%
Zinc 0.07 mg 1%
Phyto-nutrients

Carotene-ß 686 µg --
Crypto-xanthin-ß 73 µg --
Lycopene 1419 µg --

Selection and storage

Grapefruit season begins from September and lasts until December. However, fresh fruits are readily available all round the year now in supermarkets in the US. Mature fruits, which are generally harvested from the tree by mechanically, tend to get some superficial injuries. Such small abrasions on the fruit surfaces usually do not affect the quality of the fruit.

In the stores, buy fresh fruits featuring bright color; firm, yet yield to gentle pressure but recoils immediately. They should be devoid of any wrinkles on the skin, should be heavy for their size and emanate sweet aroma. Avoid overtly soften fruits with spots as they tend to perish early.

They can be kept at room temperature for few days or so but keep well for up to 3 weeks in the fruit/vegetable compartment of the home refrigerator. When kept in prolonged cold storage at temperatures below 10 degree Celsius, this fruit would subject to chilling injury.

Safety profile

Research studies have shown that many drugs interact adversely with grapefruit. Several components in grapefruit called furanocoumarins irreversibly inhibit cytochrome P450 3A4 isoenzymes (3A4) in the intestinal wall and in the liver. This enzyme inhibition decreases pre-systemic metabolism of drugs taken up to 72 hours after this fruit consumption and adversely increasing their levels in the blood. This resulting increase in drug levels leads to adverse effects and/or toxicity. It is therefore, strongly advised to consult your healthcare practitioner about consuming grapefruit juice if you are taking any kind of pharmaceutical drugs.

Some commonly used drugs interacting adversely and should be avoided with grapefruit are:-

amiodarone
astemizole (Hismanal)
atorvastatin (Lipitor)
budesonide (Entocort)
buspirone (BuSpar)
cisapride (Propulsid, Prepulsid)
lovastatin (Mevacor)
mifepristone (Mifeprex)
sildenafil (Viagra)
simvastatin (Zocor)
terfenadine (Seldane)