“Eat real food” is simple-seeming dietary advice that’s actually anything but.2 On the one hand， it sounds easy enough： It’s a guideline that appears to leave room for most food groups.3 On the other hand， though， “real food” is a slippery4 concept， one without any single established definition. And without a universal understanding of what the term describes， many people just use “real food” to mean the opposite of“processed food”—a dichotomy that doesn’t do anybody any favors.5
　　That’s because most of us don’t have a clear understanding of what “processed food” means， either. Many foods we like to think of as “whole” and “natural” undergo a fair amount of processing. As food scientist Robert Shewfelt explains， baby carrots have to be de-leaved， washed， disinfected with chlorine， chilled， cut， peeled，6 and polished prior to bagging. Bagged salads are shredded7 and triple washed， also with chlorine. Most milk in the U.S. is fortified， homogenized， and pasteurized， and that’s a good thing， as pasteurization greatly reduces the risk of foodborne illness.8 Some crops， like leafy greens， are more susceptible to pathogens，9 and processing helps get them clean. Freezing， a form of processing， can preserve nutrients， whereas fresh fruits and vegetables begin to lose those nutrients under all sorts of conditions， including exposure to heat， rough handling， and refrigeration.10
　　And while “processed food” may sound like a modernday invention， nothing could be farther from the truth.11 The history of processed food actually begins 1.8 million years ago， when our ancestors began roasting meat； two later examples are bread and beer.

　　Katherine Pett， a registered dietician， finds the term“processed food” far too nebulous.12 “Various experts who promote different ways of eating or their own food products [all] have different definitions of what constitutes processed food，” she says. The category definitely includes chips， crackers， and cookies， but it also includes things like canned tomatoes， dried pasta， and hummus.13
　　In his book In Defense of Processed Food， Robert Shewfelt defines processed food as “a product that has been modified to improve its safety， extend the shelf life， enhance its quality， and improve its convenience.”14 Processing can also open up our diets to healthy foods that might otherwise be too time-consuming or difficult to make： Beans， for example， require overnight soaking and hours of cooking， unless they’re the canned， processed kind you find on grocery-store shelves （as Pett explains， “buying a can of beans is a good and easy way to introduce beneficial legumes”）.15 The advent of bagged lettuce，16 meanwhile， likely led to an increase in our consumption of healthy leafy greens. 　　Unprocessed food， then， isn’t necessarily better. And as food historian Rachel Laudan notes in her essay “A Plea for Culinary Modernism，” processing can improve the flavor of healthy foods， too： “For our ancestors， natural was something quite nasty.17 Natural often tasted bad，” she writes. “Fresh meat was rank and tough， fresh milk warm and unmistakably a bodily excretion； fresh fruits （dates and grapes being rare exceptions outside the tropics） were inedibly sour， fresh vegetables bitter.”18
　　But what about the chemicals？ You might be thinking. Well， technically， everything is a chemical. And organic pop tarts and non-GMO chips aren’t any healthier， or less processed， than those made by Kellogg’s or Lay’s.19 Weighing the health risk of certain ingredients， it’s important to remember that old maxim： The dose makes the poison.20 Most preservatives， additives， and other chemicals in our food are present only in trace amounts that aren’t dangerous or unhealthy.21
　　In part， our suspicion of processed foods is about nostalgia22， too. The newold trend of pickling and home canning， for example， doesn’t make the end result any healthier just because the processing happens in your kitchen.23 And while we tend to feel better about homemade cookies and cakes， they usually aren’t any healthier than storebought， “processed” cookies； their advantage comes from the fact that they connect us to familial24 and cultural traditions.
　　It’s worth noting， though， that this nostalgia isn’t harmless： “While family meals of wholesome， home-cooked foods are increasingly romanticized，”as environmental historian Jennifer Bernstein wrote，“it’s likely that they are romanticized by those on the receiving end of those meals.” And as Shewfelt has noted， “shelf stable foods25， the development of ready-to-eat products， and use of microwave ovens dramatically decreased food preparation times which may have contributed to the entry of more women to the workforce.”
　　1. bad rap： 壞名声。
　　2. “吃真食物”看起来只是简单的饮食建议，但实则不然。dietary： 饮食的；anything but： 绝不是，毫不。
　　3. 一方面，这一建议听起来简单易行，因为它似乎给大多数食物都留有余地。
　　4. slippery： 不明确的。
　　5. 对于“真正的食物”没有一个统一的理解，人们就用它来指称加工食品以外的食物——然而，这一二分法却没有起到任何作用。dichotomy：二分法。
　　6. de-leaf： 脱叶；disinfect： 消毒；chlorine： 氯；chill： 冷冻，冷藏；peel：去皮。
　　7. shred： 切碎。
　　8. fortify： 加入维生素、矿物质等以提高食品的营养价值；homogenize：使牛奶中的油脂粒均匀分布；pasteurize：用巴氏消毒法对牛奶、啤酒等消毒灭菌；pasteurization： 巴氏消毒法，在某一控制温度下给液体食物或饮料加热以提高保藏质量，杀死有害的微生物；foodborne illness： 食源性疾病。 　　9. leafy greens： 绿叶菜；susceptible： 易受感染的；pathogen： 病原体，病菌。
　　10. nutrient： 营养物质；refrigeration： 冷藏。
　　11. 尽管“加工食品”听起来像是现代的发明，真相却远非如此。
　　12. dietician： 营养师；nebulous： 含糊的。
　　13. cracker： 薄脆饼干；canned tomatoes： 罐装番茄；hummus：鷹嘴豆泥，把鹰嘴豆捣碎后加麻油、大蒜、欧芹等配制成的冷食，为中东等国家的开胃食品。
　　14. In Defense of Processed Food ：《为加工食品辩护》，在本书中，作者将加工食品定义为“那些经过加工改造，改善其安全性，延长保质期，提升便捷性的产品”；shelf life： 保质期。
　　15. 食品加工也让我们能吃到更多健康食物，因为如果不经过加工的话，这些食物烹饪起来费时又费力。比如说，除非是超市货架上罐装的、加工好的豆子，未加工的豆子要泡一整晚，再煮上几个小时才能食用（正如佩特所说，吃罐装豆子能够简单又便捷地获取对人体有益的豆科植物）。legume： 豆类，豆科植物。
　　16. advent： 出现；lettuce： 生菜。
　　17. “A Plea for Culinary Modernism”：《呼吁烹饪现代主义》，在本文中，作者提出对于天然和纯手工食品的痴迷早已过时，我们应该追求更高质量的工业食品；nasty： 难吃的。
　　18. rank： 恶臭的；excretion： 排泄物，分泌物；date： 椰枣，海枣；inedibly： 不可食用地。

　　19. organic： 有机的；pop tart： 一种上面有果酱或果馅的小圆饼；GMO： 转基因生物，全称genetically modified organism；Kellogg’s： 美国家乐氏公司，在全世界出售各种谷类早餐；Lay’s： 美国薯片品牌。
　　20. ingredient： 原料，成分；maxim： 准则；The dose makes the poison： 剂量决定毒性。这是毒理学的重要信条，即所有物质都有一定毒性，必须基于使用的剂量来讨论才有意义。
　　21. preservative： 防腐剂；additive： 添加剂；trace amount： 痕量，微量，指化学上极微小的量，微小到只有一点儿痕迹。
　　22. nostalgia： 怀旧。
　　23. 比如说，当下流行但由来已久的食物腌制和罐头自制，不会因为是在自家厨房里加工的而就更加健康。pickle：腌制；home canning： 家庭自制罐头。
　　24. familial： 家庭的。
　　25. shelf stable food： 耐贮存食品。