责任编辑:徐帆 发表时间:2011/5/23 字号调整:字体缩小|字体放大
      Americans need to adopt a more plant-based diet, rich in fruits and vegetables, according to a recent report that proposed updates to federal dietary guidelines. And for good reason: Plants offer a host of health benefits. Aside from their fiber, vitamins, and minerals, evidence suggests that fruits and veggies contain compounds that play a role in preventing certain cancers as well as heart disease and stroke, for which supplements are no substitute, says dietitian Elizabeth Pivonka, president of the nonprofit Produce for Better Health Foundation.
      美国人需要进行一个以更多植物为主的饮食,富含水果和蔬菜,按照最近一个报道建议更新联邦膳食指南。因为有好的理由:植物提供有关健康的许多好处。除了它们所含有的纤维,维生素和矿物质,证据显示水果和蔬菜中含有对预防一些癌症,心脏病和中风有用的化合物,这些是补充剂所不能代替的,营养学家,非营利性的更保健农产品基金会主席Elizabeth Pivonka说。
      Beta carotene found in carrots and sweet potatoes, for example, has been shown to help protect against lung cancer, but may be harmful when taken in pill form. And the latest research suggests that calcium supplements may raise the risk of heart attacks in adults while doing little to benefit bone health. (That's why some researchers are now encouraging folks to get the nutrient in their diet instead. Spinach and broccoli are good sources.)
      Getting more isn't always easy. Supermarket produce can be expensive, making packaged snacks—already sweeter or saltier and higher in calories than fruits and vegetables—all the more tempting. A cheaper alternative: Grow your own. Home-grown produce has other advantages beyond its low cost. It's often tastier and arguably a bit more nutritious. Here's why:
      Those bright red bell peppers or crisp green beans at the supermarket are likely to have traveled many miles over several days before landing in your cart. Although both the vegetables are a good source of vitamin C—known for bolstering the immune system—a long journey from farm to table gives the nutrient ample opportunity to degrade, especially if exposed to heat. In fact, temperature is the most important factor in keeping harvested fruits and vegetables in good shape, says Diane Barrett, a food biochemist from the University of California, Davis, who helps teach best practices to locals who grow, ship, and distribute fresh produce. One would expect then that temperature is tightly controlled in transit, but in realty she says that does not always happen. 
      超市里那些鲜红的灯笼椒或新鲜的四季豆很有可能是经过几天很多英里的运输才到达你的手推车的。尽管这两种蔬菜都富含维生素C(可以增强免疫系统)但从农场到餐桌的长时间运输使其中的营养物质大大流失了,尤其是接触到高温。实际上,温度是保持摘收水果新鲜好看的最主要因素,加利福尼亚加州大学一个食品生物化学家Diane Barrett说,并帮助传授给当地人种植,运送和分配新鲜产品的最佳方法。人们会认为在运输过程中会严格控制温度,但她说实际上不一定。
      Complicating matters is that the optimal temperature differs from plant to plant, she says. Tomatoes, for example, should not be refrigerated and are generally best if stored between 50 and 55 degrees Fahrenheit. Despite the different needs of certain fruits and vegetables, they may be shipped together.
      In terms of taste, fresh is best. Supermarket tomatoes are frequently picked green before they have the chance to fully develop flavor, a technique that helps them withstand transport, says Raoul Adamchak, coordinator of the Market Garden at the UC Davis Student Farm. (Later, they are artificially ripened with ethylene.) Moreover, growers who ship their produce cross-country may favor certain varieties over others not for their taste, but because they travel well. Heirloom tomatoes, for example, are too delicate to be shipped and are often absent from store shelves.
      从味道方面来说,新鲜是最美味的。超市里的番茄通常在未熟,不能完全释放它味道的情况下就摘了,这样可以帮助它们抵抗运输过程引起的营养流失,加州大学戴维斯分校商品菜园的协调者Raoul Adamchak说。(后来,他们用乙烯人工催熟。)另外,把农产品运送到世界各地的种植者会更喜欢某些种类,不是因为它们的味道,而是因为它们运输得好。例如,祖传番茄太脆弱而不能用船运送,所以商店货架上常常缺乏。
      For your own garden, relish the freedom to pick among the most flavorful varieties (more than 400 types of tomatoes exist). And don't neglect color: Compounds called phytochemicals provide protection for plants and may give humans some padding against aging. Lycopene and beta carotene are phytochemicals; anthocyanins are another kind. Found in blueberries and cranberries, anthocyanins have been shown to aid memory. Eating an array of colors, says Pivonka, will ensure you get an assortment of nutrients and protective phytochemicals.
      Still, home-grown produce may have only a slight nutritional advantage over the store-bought kind. What really matters, says Pivonka, is that you eat more. Half your plate should contain fruits or vegetables at every meal, she says.

Copyright @2017 上海新世界外国语进修学院 版权所有All rights reserved
沪ICP备08018177号-49 沪公网安备 31010102002001号