话题链接：Proper habits of nutrition can be developed by paying attention to the variety of foods included in the diet; and the quantity of each kind of food eaten．A diet, or the food regularly eaten, must contain all the nutritional(营养的)elements．Different food contains different vitamins(维生素)，let's look at the food one by one．

　　EGGS

　　Eggs are an excellent source of complete protein(蛋白质)；they contain all essential amino acids(氨基酸)．One large egg contains 7 or 8 grams of first-class protein．Also found in eggs are vitamins A, B2, D, and E; niacin(烟酸)；copper; iron; phosphorus(磷)；and unsaturated(不饱和的)fats．The egg yolk contains the richest known source of choline, found in lecithin and necessary for keeping the cholesterol (胆固醇)within the egg emulsified(蛋白)．The egg yolk also contains biotin(维生素H)，one of the B-complex vitamins．

　　FIBER

　　Fiber is the part of food that is not digested by the human body, such as the skin of an apple and the husk(壳，皮)of a wheat kernel．The normal functioning of the intestinal tract depends upon the presence of adequate fiber．A low-fiber diet has been associated with heart disease, cancer of the colon and rectum(直肠)，diverticulosis(瘢痕形成)，varicose veins(纹理)，phlebitis(静脉炎)，and obesity．

　　FISH

　　Fish are excellent sources of high-grade protein, polyunsaturated fatty acids, and minerals, especially iodine(碘)and potassium(钾)．Fish are categorized as freshwater fish, saltwater fish, and shellfish．These types differ slightly in nutritive value．Freshwater fish provide magnesium(镁)，phosphorus, iron, and copper．Saltwater fish and shellfish are rich in iodine, fluorine(氟)，and cobalt (钴)．Fatty fish, such as halibut(比目鱼)，mackerel(鲭鱼)，and salmon, are good sources of vitamins A and D．Herring, oysters, and sardines contain vanadium and zinc．Shellfish are low fatty acids but are relatively high in cholesterol．

　　FRUITS

　　Fresh fruits are good sources of vitamins and minerals, especially vitamin A and C, carbohydrates in the form of cellulose and natural sugars, and water．They are good substitutes of such high-carbohydrate(碳水化合物)foods as candy, cookies, and cakes, which contain few nutrients．Yellow fruits, such as apricots, cantaloupe(香瓜)，and persimmons(柿子)，are good sources of carotene(胡萝卜素)，which is converted to vitamin A．Aside from acerola cherries and rose hips, the best natural sources of vitamin C are the citrus fruits, such as oranges, grapefruit, lemons, and tangerines(橘)；other sources of vitamin C are cantaloupe, strawberries, and tomatoes．Apples and bananas contain valuable bulk fiber in the form of indigestible(不可吸收的)cellulose, which is needed for regular bowel movement．Bananas are high in magnesium(镁)and may be useful for treatment of diarrhea, colitis, ulcers, and certain cases of protein allergies．Bananas and pears are the highest in natural sugars．

　　GRAINS

　　Grains are often referred to as cereals ;they are the seeds of various grasses such as wheat, oats, rice, and barley．Often called the “staff of life”, they provide the bulk of the world's food supply．Common foods made from these grains are flours, breads, breakfast cereals, and macaroni．

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想一想：Healthy eating is the essential thing for the physical and mental development for human being．But the eating habit of our Chinese people is not very reasonable or suitable．If you are responsible for the improvement of the Chinese healthy eating, what will you do to change the formed eating habit of Chinese people?