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在过去的二十多年里,科学家已经发现日常饮食中要富含水果和蔬菜的缘故,不仅是因为它们含有大量的维生素和植物纤维,更重要的是它们含有植物化学素。所有的植物都含有这种化合物,保护它们免受各种危险——从有害的紫外线到食草性动物。人体在进食时吸收的植物化学素也会起到保护健康的作用。其中一些起到了抗氧化剂的作用,能够消灭不稳定的自由基分子,后者会对细胞造成破坏作用,导致心脏病、癌症、老年痴呆症和其他一些疾病的形成。另外一些植物化学素能够提高免疫系统的功能。自然界的奇妙之处就在于它能让这些有益的营养元素带有明亮的色彩,从而让人们一眼就发现它们。比如,花青素让越橘呈现蓝色,能让人思维保持敏锐。番茄的红宝石色调来自番茄红素,有预防前列腺癌的作用。为了起到最大限度的预防疾病的效果,要尽可能的选择五颜六色的食物。美国农业部(USDA)建议人们每周至少要吃两份橙色和三份深绿色的农产品,因为它们富含维生素A和其他重要的营养元素。
For the past two decades or so scientists have discovered that fruits and vegetables are often consumed in daily diets not only because they contain large amounts of vitamins and plant fibers, but more importantly, they contain phytochemicals. All plants contain this compound to protect them from a variety of hazards - from harmful UV rays to herbivores. Phytochemicals absorbed by the human body during eating also serve to protect the health. Some of them act as antioxidants to eliminate unstable free radical molecules, which can cause damaging effects on cells, leading to the formation of heart disease, cancer, Alzheimer’s disease and other diseases. Some other phytochemicals boost the immune system’s function. The wonders of nature are that it gives these beneficial nutrients a bright color so they can be found at a glance. For example, anthocyanins make blueberry blue, people can keep their minds keen. Tomato ruby color comes from lycopene, have the effect of preventing prostate cancer. In order to play the maximum effect of disease prevention, as far as possible the choice of colorful food. The USDA recommends that people eat at least two servings of orange and three dark greens per week because they are rich in vitamin A and other important nutrients.