吃什么才健康？難道醫(yī)生也靠猜？.

　　First doctor: “This morning for breakfast he requested something called ‘wheat germ,organic honey and tiger’s milk.’”

　　醫(yī)生甲說：“那家伙說今天早餐想吃……某種叫做‘小麥胚芽、有機(jī)蜂蜜和Tiger's Milk有機(jī)蛋白質(zhì)營養(yǎng)棒’的東西。”

　　Second doctor: “Oh, yes. Those are the charmed substances that some years ago werethought to contain life-preserving properties.”

　　醫(yī)生乙：“對(duì)啊。很多年前，人們對(duì)這些東西可著迷啦，他們篤信這里面含有維持生命必備的營養(yǎng)成分?！?/p>

　　Fans of Woody Allen may recognize that snippet of dialogue from his 1973 comedy, “Sleeper.”The main character, a health-food store owner somehow frozen in 1973, has been thawed out200 years later. He awakens to a world he can barely fathom, down to the kinds of food nowsaid to constitute a sound diet. Everything that nutrition specialists once said was good foryou, or really bad, turned out to be wrong.

　　如果你是伍迪·艾倫(Woody Allen)的粉絲，或許你已經(jīng)認(rèn)出上述對(duì)話是他1973年的喜劇電影《傻瓜大鬧科學(xué)城》(Sleeper)中的片段。影片的主角是一名健康食品商店的老板，1973年他莫名其妙地被冷凍了起來，直到200年后才被解凍。他蘇醒過來，發(fā)現(xiàn)自己來到了一個(gè)令他迷惑不解的新世界，就連所謂的“健康食品”也改變了——過去被營養(yǎng)專家宣稱是對(duì)人大有益處或害處的東西，后來發(fā)現(xiàn)都不是那么回事兒。

　　First doctor: “You mean there was no deep fat? No steak or cream pies or hot fudge?”

　　醫(yī)生甲：“你是說，不包括油炸食品?也沒有牛排、奶油餡餅或熱巧克力?”

　　Second doctor: “Those were thought to be unhealthy — precisely the opposite of what we nowknow to be true.”

　　醫(yī)生乙：“他們覺得這些東西不健康——不過，我們現(xiàn)在知道，事實(shí)恰恰相反呀?！?/p>

　　Moviegoers laughed. They recognized how they were whipsawed by contradictory expertpronouncements about what they should or should not eat to stay healthy. On this score, notmuch has changed. How many times have Americans read about a study damning this or thatfood, only to then hear the revisionist opposite? Avoid eggs, we were told; they clog yourarteries. Wait, we then heard, eggs have nutritional value. Coffee can give you cancer. Hold on,coffee can improve brain function. Butter is terrible. Well, not really. Again and again,yesterday’s verity becomes today’s punch line.

　　看到這里，觀眾們紛紛大笑起來。他們意識(shí)到，關(guān)于為了保持健康應(yīng)該或不應(yīng)該吃什么，專家們一直在給他們灌輸相互矛盾的意見，讓他們莫衷一是——只有這一點(diǎn)似乎一直都沒有改變。多少次，一項(xiàng)研究言之鑿鑿，宣稱這種或那種食物“罪大惡極”，結(jié)果不久，就又有人提出相反的論斷。我們被告知不要吃雞蛋，因?yàn)樗鼈儠?huì)堵塞你的動(dòng)脈——接著我們又聽說，雞蛋頗具營養(yǎng)價(jià)值;咖啡會(huì)害你患癌癥——等等，咖啡可以改善腦功能;黃油簡直糟透了——好吧，其實(shí)也并非如此。一次又一次，昨天被奉為至理名言的，變成了今天的笑話。

　　The vagaries of nutrition claims infuse the latest episode of Retro Report, videodocumentaries exploring major news developments of the past and how they still resound.This installment harks back to the 1970s, when many health authorities asserted, withunshakable confidence, that a diet low in fat and cholesterol was essential for a healthful life(wheat germ and tiger’s milk presumably optional).

　　最近一期的“Retro Report”(回顧歷史上的重大新聞，并探討其現(xiàn)實(shí)意義的系列電視紀(jì)錄片)中就充斥著此類變幻莫測的營養(yǎng)學(xué)聲明。這期節(jié)目回顧了上世紀(jì)70年代，當(dāng)時(shí)，眾多衛(wèi)生部門都以堅(jiān)不可摧的信心聲稱，低脂肪和低膽固醇的飲食(譬如小麥胚芽和Tiger's Milk有機(jī)蛋白質(zhì)營養(yǎng)棒之類)是健康生活必不可少的一部分。

　　“Fat-free” became a mantra, not to mention a marketing tool to sell breakfast cereals and high-caloric snacks. If anyone qualified as a heretic back then, it was Dr. Robert C. Atkins, acardiologist who died in 2003. The Atkins diet encouraged loading up on fat-laden foods likesteaks and omelets, and steering clear of pasta, bread and other carbohydrates.

　　“脫脂”仿佛成了一個(gè)魔咒，更不用說它實(shí)際上已經(jīng)化身為推銷早餐谷物和高熱量小食品的一種營銷工具。而在當(dāng)年，要說特立獨(dú)行離經(jīng)叛道，當(dāng)屬心臟病醫(yī)生羅伯特·C·阿特金斯(Robert C. Atkins)博士了(他在2003年去世)。阿特金斯飲食法鼓勵(lì)人們大量進(jìn)食高脂肪食物，如牛排和煎蛋卷等，同時(shí)避免食用意面、面包等碳水化合物。

　　But conventional wisdom held that fat was bad, period, with relatively few Americansdistinguishing between saturated fats (meat, eggs, dairy products) and healthier unsaturatedfats (fish, vegetable oils, nuts). Typically, people turned to breads, cereals and potatoes — andto sugary soft drinks — for the calories they no longer got from protein-rich foods.

　　但傳統(tǒng)觀念認(rèn)為脂肪不是好東西，句號(hào)，一度只有少數(shù)美國人能對(duì)飽和脂肪(肉、蛋、乳制品)和較為健康的不飽和脂肪(魚、植物油、堅(jiān)果)區(qū)別對(duì)待。通常，人們只是直接轉(zhuǎn)而食用面包、谷物、土豆以及含糖軟飲料，以便獲得他們?cè)緫?yīng)從富含蛋白質(zhì)的食物中攝取的熱量。

　　“Diet is a trade-off,” Gary Taubes, a science journalist and the author of “Why We Get Fat,” toldRetro Report. “If we reduce the amount of fat, you have to replace it with something.” Thatsomething tended to be carbohydrates. The result? Carbo-loading Americans grew fatter. “Weput the whole country on a low-fat diet,” Mr. Taubes said, “and, lo and behold, we have anobesity epidemic.”

　　“膳食是個(gè)交易過程，”《我們?yōu)槭裁磿?huì)發(fā)胖?》(“Why We Get Fat”)一書的作者，科學(xué)記者蓋里·陶比斯(Gary Taubes)在接受”Retro Report”采訪時(shí)說?！叭绻覀儨p少了脂肪的攝入量，就必須用別的什么東西來替代它?！薄热缣妓衔?。結(jié)果，大量食用碳水化合物，讓美國人變得更胖了。陶比斯先生說：“在整個(gè)國家推行低脂肪飲食后，瞧啊，肥胖大肆流行了開來?！?/p>

　　Obesity has proved a stubborn plague, one that the Centers for Disease Control andPrevention says affects 35 percent of American adults — about 79 million people. Tens ofmillions more, while not technically obese, are overweight. Not coincidentally, diabetes is a bignational headache, even if the C.D.C. reported last month that new cases of the disease hadbegun to decline.

　　肥胖已成為一個(gè)頑疾，美國疾病控制和預(yù)防中心(Centers for Disease Control and Prevention，CDC)的工作人員表示，在美國的成年人中，肥胖者人數(shù)高達(dá)7900萬，占35%。還有數(shù)以千萬計(jì)的人雖然嚴(yán)格來說算不上肥胖，至少也是超重的。無獨(dú)有偶，雖然據(jù)CDC上個(gè)月報(bào)道，糖尿病的新病例數(shù)開始下降了，但它仍是令美國頭痛的一大疾病。

　　As for that low-fat diet, a major federal study concluded in 2006 that its health benits weregreatly overrated. Such a diet, researchers found, had no fect on the risk of heart disease orcancer, the two biggest killers in the United States

　　2006年美聯(lián)邦進(jìn)行的一項(xiàng)重大研究顯示，低脂肪飲食的健康效益被大大高估了。研究人員發(fā)現(xiàn)，這種飲食對(duì)美國致死率最高的兩大疾病——心臟病和癌癥的風(fēng)險(xiǎn)并沒有影響

　　This Retro Report episode comes as the federal government is again rethinking its DietaryGuidelines for Americans. They form a nutrition template that Washington issues every fiveyears and is a bible for millions of the diet-conscious, whose numbers undoubtedly includemany who overindulged during the holidays and entered the new year with a pledge to shedpounds.

　　本期“Retro Report”的推出，正值聯(lián)邦政府再次反思其《美國膳食指南》(Dietary Guidelines forAmericans)之際。這些每隔五年由華盛頓發(fā)布的指南得到了數(shù)以百萬計(jì)的注重飲食者的追捧，并視其為營養(yǎng)模板和飲食圣經(jīng)，毫無疑問，眾多在節(jié)假日里胡吃海喝，而后又在新年伊始許愿一定要減肥的人也在其中。

　　The new guidelines are expected to be issued this month by the Departments of Agriculture andof Health and Human Services, which tend to follow the recommendations of an advisorycommittee. One likely eye-catcher is a new assessment of cholesterol, long an archvillain. Itseems destined for rehabilitation to some degree. Months ago, the advisory committeeconcluded that the dietary intake of cholesterol (the body produces this waxy, artery-obstructing matter on its own) had no real fect on blood levels of LDL, the so-called badcholesterol. “Cholesterol,” the committee said, “is not a nutrient of concern foroverconsumption.”

　　預(yù)計(jì)新指南將在本月由美國衛(wèi)生和公眾服務(wù)部(Department of Health and Human Service)和農(nóng)業(yè)部(Department of Agriculture)發(fā)布。這些指南通常都會(huì)遵循顧問委員會(huì)的建議。其中，一項(xiàng)關(guān)于膽固醇的新評(píng)估很可能將十分引人注目。長期以來，膽固醇一直被視為洪水猛獸，而該評(píng)估可以說在一定程度上為它平了反。幾個(gè)月前，該顧問委員會(huì)得出結(jié)論，從膳食中攝取膽固醇(人體自己也會(huì)產(chǎn)生這種會(huì)阻塞動(dòng)脈的蠟狀物)對(duì)LDL(低密度脂蛋白膽固醇)，也就是所謂的“壞膽固醇”的血液濃度沒有實(shí)質(zhì)影響。該委員會(huì)稱：“我們無需擔(dān)心過度攝取膽固醇。”

　　There is a conspicuous American tendency to cling to a favored diet as the gateway to goodhealth, keeping weight down, staving off cancers and banishing heart attacks. A consequenceis an abundance of regimens — vegan, gluten-free, Paleolithic, fruitarian and many more —each promoted by its adherents as the one true path.

　　美國人中存在著一種非常明顯的傾向，總是喜歡追捧某種特殊的飲食，以為它是能讓你身體健康、保持體重、預(yù)防癌癥、避免心肌梗死的唯一制勝法寶。結(jié)果，各種各樣的膳食方案層出不窮：素食主義、無麩質(zhì)飲食、舊石器時(shí)代飲食(Paleolithic，又譯，古式飲食)、果食主義等等，每一種都擁有大批忠貞不二的擁躉。

　　But nutrition experts, including those in this Retro Report, caution that life is complex, andthat we are more than what we eat. Among them is Dr. Barbara V. Howard, who was a principalinvestigator in the 2006 federal study of low-fat diets.

　　但營養(yǎng)專家，包括本期“Retro Report”中的專家們都警告，生命遠(yuǎn)比吃什么東西復(fù)雜得多。芭芭拉·V·霍華德(Barbara V. Howard)博士也是其中之一，她是2006年美聯(lián)邦一項(xiàng)低脂肪飲食研究的首席研究員。

　　“We are not going to reverse any of the chronic diseases in this country by changing thecomposition of the diet,” Dr. Howard said when that report was issued. “People are alwaysthinking it’s what they ate. They are not looking at how much they ate, or that they smoke orthat they are sedentary.”

　　“在這個(gè)國家中，改變飲食結(jié)構(gòu)是無法逆轉(zhuǎn)任何慢性疾病的，”霍華德博士在發(fā)布上述研究報(bào)告時(shí)說道。“人們總覺得問題出在食物身上，卻從不留心自己的食量，以及吸煙與否或是否存在久坐不動(dòng)的生活習(xí)慣等。”

　　Other explanations for why one person gains weight and someone else does not may includesleep patterns, genetic predispositions and the compositions of individual microbiomes — thetrillions of microbes residing inside the human body. Some health researchers even question thesignificance of exercise in keeping pounds off, regardless of its other benits. Among otherthings, one has to move around quite vigorously to hold the weight down. A Big Mac, forinstance, has 540 calories. To burn it off, a person would need to jog or to swim laps for about45 minutes. Not every Big Mac eater exercises that strenuously.

　　對(duì)于為何有些人容易發(fā)胖而其他人則不然，還有些其他的解釋，例如睡眠模式、遺傳傾向和個(gè)人的微生物組(也就是棲息在人體內(nèi)的數(shù)萬億微生物的總和)等。有些健康研究人員甚至對(duì)運(yùn)動(dòng)在保持體重中的重要性提出了質(zhì)疑——雖然他們承認(rèn)它可以帶來其他好處。別的先不說，要控制體重，一個(gè)人非積極地運(yùn)動(dòng)不可。例如，一個(gè)巨無霸(Big Mac)含有540卡路里的熱量。要消耗掉這些熱量，需要慢跑或游泳45分鐘。顯然，不是每個(gè)吃巨無霸的人都會(huì)這么勤奮地鍛煉的。

　　Politics, too, can enter the picture. An example is the experience of Michael R. Bloomberg, aforcul public-health advocate when he was New York’s mayor. Despite resistance fromrestaurant owners and their political allies, Mr. Bloomberg pushed through a ban on trans fats(almost universally deemed a health hazard), and required fast-food outlets to post caloriecounts.

　　政治在飲食問題中也占有一席之地。就拿邁克爾·R·布隆伯格(Michael R. Bloomberg)的經(jīng)歷為例吧，他在擔(dān)任紐約市長時(shí)是一位強(qiáng)有力的公眾健康倡導(dǎo)者。盡管遭遇了來自餐館老板和他們的政治盟友的阻力，布隆伯格依然力促通過了對(duì)反式脂肪(普遍認(rèn)為它有害健康)的禁令，并要求快餐店公布其產(chǎn)品的卡路里計(jì)數(shù)。

　　But he hit a political and a juridical wall when he also sought to restrict the sale of sodas andother sugary drinks of dubious nutritional value. State courts shot down his plan on proceduralgrounds. Mr. Bloomberg found himself widely denounced for having taken governmentnannyism too far.

　　然而，當(dāng)他試圖限制汽水和其他營養(yǎng)價(jià)值存疑的含糖飲料的銷售時(shí)，在政治和法律兩方面都碰了壁。州法院基于程序上的原因駁回了他的議案。布隆伯格也因?yàn)樽屨α恕澳虌屩髁x”病(nannyism，禁止任何“可能”導(dǎo)致傷害的事情——譯注)而廣受批評(píng)。

　　Then again, no one ever said figuring out the elements of a healthy diet would be easy. Dr.Dariush Mozaffarian, a nutrition specialist at Tufts University, suggested to Retro Report thataccepted wisdom was not necessarily wise. Much of what has shaped dietary guidelines, he said,are “basically best guesses.” Uncertainty abounds. “I think now we know about 50 percent ofwhat we need to know,” Dr. Mozaffarian said.

　　不過話說回來，要找到健康飲食的要素絕非易事。塔夫茨大學(xué)(Tufts University)的營養(yǎng)學(xué)專家戴瑞什·莫薩法利安(Dariush Mozaffarian)博士向“Retro Report”表示，受到廣泛認(rèn)可的觀念未必就是正確的。他說，膳食指南中的大部分內(nèi)容“基本上都是些‘最佳猜測’(best guess)，”充滿了不確定性。他還說：“我認(rèn)為我們目前所知的，只占應(yīng)該和需要知道的50%左右?！?/p>

　　So is it possible that steaks, cream pies and hot fudge will someday be called the cornerstonesof a healthy diet? Maybe if you can stick around for 200 years, you’ll find out.

　　既然如此，有朝一日人們會(huì)不會(huì)將牛排、奶油餡餅和熱巧克力列為健康飲食的重要組成部分?努力再活上個(gè)200年，你就知道啦。