2014年英语四级阅读练习及答案(17)_大学英语阅读

2014年英语四级阅读练习及答案(17)

　　Zinc and vitamin A are important for normal, healthy skin. Zinc helps the skin repair itself, and vitamin A aids in keeping skin supple, preventing dryness and helping shed dead cells. Good sources of zinc are beef, eggs and seafood, while many dark-green leafy vegetables are rich in beta carotene, which the body converts to vitamin A. Other foods containing ample amounts of beta carotene include carrots, cantaloupe, winter squash, sweet potatoes, sweet red peppers, apricots and mangoes.

　　Vitamin C helps improve the blood supply to the skin and aids in forming collagen , the fibrous protein that lies beneath the skin s surface and gives it a smooth appearance. Good sources of vitamin C include citrus fruits and juices, Brussels sprouts, cauliflower, snow peas, red and green peppers, broccoli, white and sweet potatoes, tomatoes, watermelon, honeydew melon and cantaloupe.

　　Greens are excellent sources of skin-preserving nutrients and, generally, the darker the leaves, the more nutritious. Romaine lettuce, for example has about six times as much vitamin C and eight times as much beta carotene as iceberg lettuce.

　　How food is prepared matters too. The longer vegetables cook, the greater the loss of vitamins and texture. Don t soak vegetables when washing them, since water-soluble vitamins such as C will be lost.

　　Blumberg also recommends drinking six to eight glasses of water or other fluids each day to help keep skin and other tissues hydrated. That s especially important for older people, he says, who are at risk for dehydration because their thirst drive becomes blunted with age. Coffee, colas and tea aren t the best sources, since they contain caffeine, a diuretic that induces water loss.