多吃紅肉，真的不健康嗎?

Red Meat Is Not the Enemy

多吃紅肉，真的不健康嗎?

There are people in this country eating too much red meat. They should cut back. There are people eating too many carbs. They should cut back on those. There are also people eating too much fat, and the same advice applies to them, too.

在美國(guó)，有些人食用紅肉太多，他們應(yīng)該少吃點(diǎn);也有些人食用碳水化合物太多，他們也應(yīng)該克制;還有些人食用脂肪太多，相同的建議也適用于他們。

What’s getting harder to justify, though, is a focus on any one nutrient as a culprit for everyone.

把某一營(yíng)養(yǎng)物質(zhì)說(shuō)成是危害所有人健康的罪魁禍?zhǔn)椎恼f(shuō)法，正變得越來(lái)越難以自圓其說(shuō)。

I’ve written Upshot articles on how the strong warnings against salt and cholesterol are not well supported by evidence. But it’s possible that no food has been attacked as widely or as loudly in the past few decades as red meat.

此前，我已在《紐約時(shí)報(bào)》的Upshot專欄中撰文，闡述那些關(guān)于鹽和膽固醇的強(qiáng)烈警告其實(shí)并沒有得到充分的證據(jù)支持。不過(guò)，在過(guò)去的幾十年里，恐怕任何一種食物受到的攻擊都沒有紅肉這樣廣泛和強(qiáng)烈。

As with other bad guys in the food wars, the warnings against red meat are louder and more forceful than they need to be.

與食品戰(zhàn)爭(zhēng)中的其他“壞東西”一樣，對(duì)食用紅肉的警告已經(jīng)大大超過(guò)了實(shí)際需要的程度。

Americans are more overweight and obese than they pretty much have ever been. There’s also no question that we are eating more meat than in previous eras. But we’ve actually been reducing our red meat consumption for the last decade or so. This hasn’t led to a huge decrease in obesity rates or to arguments from experts that it is the reason for fewer deaths from cardiovascular disease.

今天美國(guó)人超重和肥胖的程度基本上都甚于以往，我們也毫無(wú)疑問(wèn)是比以前吃肉多。然而，在過(guò)去十年左右的時(shí)間里，我們的紅肉消費(fèi)量實(shí)際上是在逐漸減少的?？蛇@并沒有引起肥胖率大幅下降，也沒有專家認(rèn)為它是心血管疾病死亡人數(shù)減少的原因。

The same reports also show that we eat significantly more fruits and vegetables today than we did decades ago. We also eat more grains and sweeteners.

同樣，報(bào)告還顯示，我們今天食用水果和蔬菜的量顯著多于幾十年前。我們還吃下了更多的谷物和甜味劑。

This is the real problem: We eat more calories than we need. But in much of our discussion about diet, we seek a singular nutritional guilty party. We also tend to cast everyone in the same light as “eating too much.”

這才是真正的問(wèn)題：我們攝入的熱量超過(guò)了實(shí)際所需。但是，在大多數(shù)關(guān)于飲食的討論中，我們都試圖把責(zé)任歸咎于某一類營(yíng)養(yǎng)物質(zhì)。而且，我們也傾向于給所有人都套上“吃得太多”的大帽子。

I have seen many people point to a study from last year that found that increased protein intake was associated with large increases in mortality rates from all diseases, with high increases in the chance of death from cancer or diabetes. A close examination of the manuscript, though, tells a different story.

我見過(guò)有很多人拿著去年的一項(xiàng)研究振振有詞，稱該研究發(fā)現(xiàn)，蛋白質(zhì)攝入量的增加與因所有疾病死亡率以及因癌癥或糖尿病死亡的幾率大幅增加相關(guān)。然而，在仔細(xì)閱讀文獻(xiàn)后，我發(fā)現(xiàn)它說(shuō)的完全是另外一回事。

This was a cohort study of people followed through the National Health and Nutrition Examination Survey, or Nhanes. It found that there were no associations between protein consumption and death from all causes or cardiovascular disease or cancer individually when all participants over age 50 were considered. It did detect a statistically significant association between the consumption of protein and diabetes mortality, but the researchers cautioned that the number of people in the analysis was so small that any results should be taken with caution.

這是一項(xiàng)隊(duì)列研究，研究人員通過(guò)美國(guó)健康與營(yíng)養(yǎng)調(diào)查(National Health and Nutrition Examination Survey, Nhanes)對(duì)參與者進(jìn)行了隨訪。研究發(fā)現(xiàn)，當(dāng)考慮到所有50歲以上的參與者時(shí)，蛋白質(zhì)攝入量與全因死亡率、心血管疾病死亡率以及癌癥死亡率中的任何一項(xiàng)均無(wú)相關(guān)性。研究的確發(fā)現(xiàn)蛋白質(zhì)攝入量與糖尿病死亡率之間具有統(tǒng)計(jì)學(xué)顯著相關(guān)性，但研究人員提醒說(shuō)，由于該分析中納入的人數(shù)過(guò)少，應(yīng)謹(jǐn)慎對(duì)待由此得出的任何結(jié)果。

The scary findings from two paragraphs up are from a subanalysis that looked at people only 50 to 65. But if you look at people over 65, the opposite was true. High protein was associated with lower levels of all-cause and cancer-specific mortality. If you truly believe that this study proves what people say, then we should advise people over the age of 65 to eat more meat. No one advises that.

而上面倒數(shù)第二段中那個(gè)可怕的結(jié)論只不過(guò)是一項(xiàng)僅考察50歲到65歲參與者的亞組分析的結(jié)果而已。如果你將調(diào)查的對(duì)象改為65歲以上的參與者，就會(huì)發(fā)現(xiàn)情況恰恰相反。高蛋白攝入量與較低的全因死亡率和癌癥特異性死亡率相關(guān)。如果你相信這項(xiàng)研究為應(yīng)該少吃紅肉提供了證據(jù)，那么我們也應(yīng)該建議65歲以上的人多吃些肉——顯然并沒有人這么做。

Further, this study defined people in the “high protein” group as those eating 20 percent or more of their calories from protein. When the Department of Agriculture recommends that Americans get 10 to 35 percent of their calories from protein, 20 percent should not be considered high.

此外，這項(xiàng)研究對(duì)“高蛋白質(zhì)”組成員的定義為：飲食總熱量中有至少20%來(lái)自蛋白質(zhì)?？紤]到美國(guó)農(nóng)業(yè)部(United States Department of Agriculture,USDA)建議美國(guó)人從蛋白質(zhì)獲得的熱量應(yīng)占所需熱量的10%至35%，20%其實(shí)不能算高。

If I wanted to cherry-pick studies myself, I might point you to this 2013 study that used the same Nhanes data to conclude that meat consumption is not associated with mortality at all.

如果允許我自己來(lái)挑選的話，我也能找出一項(xiàng)2013年的研究，它使用了相同的Nhanes數(shù)據(jù)，卻得出了相反的結(jié)論：肉類消費(fèi)量與死亡率毫不相關(guān)。

Let’s avoid cherry-picking, though. A 2013 meta-analysis of meat-diet studies, including those above, found that people in the highest consumption group of all red meat had a 29 percent relative increase in all-cause mortality compared with those in the lowest consumption group. But most of this was driven by processed meats, like bacon, sausage or salami.

不過(guò)，我們還是不要刻意去挑選吧。2013年的一項(xiàng)關(guān)于肉類膳食研究的薈萃分析納入了上述的幾類情況，分析結(jié)果發(fā)現(xiàn)：與紅肉消費(fèi)量最低組相比，最高組成員的全因死亡率增加了29%，但這一增加主要是由加工肉類，如培根、臘腸或意大利香腸等造成的。

Epidemiologic evidence can take us only so far. As I’ve written before, those types of studies can be flawed. Nothing illustrates this better than a classic 2012 systematic review that pretty much showed that everything we eat is associated with both higher and lower rates of cancer.

流行病學(xué)證據(jù)能告訴我們的也只有這么多了。正如我之前所說(shuō)，這類研究有可能存在缺陷。2012年的一項(xiàng)典型的系統(tǒng)性綜述就是最好的佐證：該綜述表明，幾乎我們的所有食物都同時(shí)與較高和較低的癌癥發(fā)病率相關(guān)。

We really do need randomized controlled trials to answer these questions. They do exist, but with respect to effects on lipid levels such as cholesterol and triglycerides. A meta-analysis examining eight trials found that beef versus poultry and fish consumption didn’t change cholesterol or triglyceride levels significantly.

所以，我們需要進(jìn)行隨機(jī)對(duì)照試驗(yàn)才能真正找到問(wèn)題的答案。這樣的實(shí)驗(yàn)確實(shí)是存在的，不過(guò)卻是關(guān)于膽固醇和甘油三酯等血脂水平指標(biāo)的。一項(xiàng)薈萃分析審查了八項(xiàng)試驗(yàn)，發(fā)現(xiàn)與食用禽肉和魚肉相比，食用牛肉并不會(huì)顯著改變?nèi)说哪懝檀蓟蚋视腿ニ健?/p>

All of this misses the bigger point, though. It’s important to understand what “too much” really is. People in the highest consumption group of red meat had one to two servings a day. The people in the lowest group had about two servings per week. If you’re eating multiple servings of red meat a day, then, yes, you might want to cut back. I would wager that most people reading this aren’t eating that much. If you eat a couple of servings a week, then you’re most likely doing fine.

但是，所有這些都忽略了更重要的一點(diǎn)——“太多”的標(biāo)準(zhǔn)到底是什么。紅肉消費(fèi)量最高組的人每天食用一至兩份紅肉，而最低組的人每周才食用大約兩份。如果你每天都吃好幾份紅肉，那么，沒錯(cuò)，你是需要控制一下了。但我敢打賭，正在閱讀這篇文章的人中大多數(shù)都不會(huì)吃那么多。如果你每周食用一兩份紅肉，那么最有可能的情況是：你的身體一切正常。

All the warnings appear to have made a difference in our eating habits. Americans are eating less red meat today than any time since the 1970s. Doctors’ recommendations haven’t been ignored. We’re also doing a bit better in our consumption of vegetables. Our consumption of carbohydrates, like grains and sugar, however, has been on the rise. This is, in part, a result of our obsession with avoiding fats and red meat.

健康警告大大改變了我們的飲食習(xí)慣。美國(guó)人今天的紅肉消費(fèi)量比20世紀(jì)70年代以來(lái)的任何時(shí)候都少。人們并沒有忽略醫(yī)生的建議。我們?cè)谑秤檬卟朔矫嬉踩〉昧艘稽c(diǎn)進(jìn)步。但我們對(duì)谷物和糖等碳水化合物的消費(fèi)量卻一直在上升。在某種程度上，可以說(shuō)這正是我們執(zhí)著于不吃脂肪和紅肉的后果。

We’re eating too many calories, but not necessarily in the same way. Reducing what we’re eating too much of in a balanced manner would seem like the most sensible approach.

我們?nèi)匀粩z入了太多的熱量，只不過(guò)改了個(gè)途徑罷了。最明智的做法應(yīng)該是以平衡的方式少吃那些我們過(guò)量食用的東西才對(duì)。

Last fall, a meta-analysis of brand-name diet programs was published in the Journal of the American Medical Association. The study compared the results from both the individual diets themselves and three classes, which included low-carbohydrate (like Atkins), moderate macronutrient (Weight Watchers) and low-fat (Ornish). All of the diets led to reduced caloric intake, and all of them led to weight loss at six months and, to a lesser extent, at 12 months. There was no clear winner, nor any clear loser.

去年秋天，《美國(guó)醫(yī)學(xué)協(xié)會(huì)雜志》(Journal of the American Medical Association)上發(fā)表了一項(xiàng)對(duì)著名飲食方案的薈萃分析。該研究既比較了單個(gè)的飲食方案，也對(duì)三大類飲食方案：低碳水化合物飲食(如阿特金斯飲食法[Atkins])，中度宏量營(yíng)養(yǎng)素飲食(如Weight Watcher)和低脂肪飲食(如Ornish飲食)進(jìn)行了比較。所有的飲食方案都減少了熱量攝入，它們都能令參與者在六個(gè)月后體重減輕，并在接下來(lái)的六個(gè)月里繼續(xù)減輕(但減重幅度較小)。它們之間并沒有表現(xiàn)出明顯的優(yōu)劣。

Where does that leave us? It’s hard to find a take-home message better than this: The best diet is the one that you’re likely to keep. What isn’t helpful is picking a nutritional culprit of bad health and proclaiming that everyone else is eating wrong. There’s remarkably little evidence that that’s true anytime anyone does it.

這給我們帶來(lái)什么啟示?你最有可能堅(jiān)持下來(lái)的飲食方案就是最好的飲食方案——世界上最棒的教益或許莫過(guò)于此。把健康狀況不佳歸咎于某一特定的營(yíng)養(yǎng)物質(zhì)，并宣稱其他人的飲食習(xí)慣都不對(duì)，這樣做沒有一點(diǎn)好處。很顯然，任何時(shí)候任何人這么做都是毫無(wú)根據(jù)的。