多吃红肉，真的不健康吗？

Red Meat Is Not the Enemy
多吃红肉，真的不健康吗？

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.

在美国，有些人食用红肉太多，他们应该少吃点；也有些人食用碳水化合物太多，他们也应该克制；还有些人食用脂肪太多，相同的建议也适用于他们。

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

把某一营养物质说成是危害所有人健康的罪魁祸首的说法，正变得越来越难以自圆其说。

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《纽约时报》的Upshot专栏中撰文，阐述那些关于盐和胆固醇的强烈警告其实并没有得到充分的证据支持。不过，在过去的几十年里，恐怕任何一种食物受到的攻击都没有红肉这样广泛和强烈。

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

与食品战争中的其他“坏东西”一样，对食用红肉的警告已经大大超过了实际需要的程度。

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.

今天美国人超重和肥胖的程度基本上都甚于以往，我们也毫无疑问是比以前吃肉多。然而，在过去十年左右的时间里，我们的红肉消费量实际上是在逐渐减少的。可这并没有引起肥胖率大幅下降，也没有专家认为它是心血管疾病死亡人数减少的原因。

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.

同样，报告还显示，我们今天食用水果和蔬菜的量显著多于几十年前。我们还吃下了更多的谷物和甜味剂。

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.”

这才是真正的问题：我们摄入的热量超过了实际所需。但是，在大多数关于饮食的讨论中，我们都试图把责任归咎于某一类营养物质。而且，我们也倾向于给所有人都套上“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.

我见过有很多人拿着去年的一项研究振振有词，称该研究发现，蛋白质摄入量的增加与因所有疾病死亡率以及因癌症或糖尿病死亡的几率大幅增加相关。然而，在仔细阅读文献后，我发现它说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.

这是一项队列研究，研究人员通过美国健康与营养调查(National Health and Nutrition Examination Survey, Nhanes)对参与者进行了随访。研究发现，当考虑到所有50岁以上的参与者时，蛋白质摄入量与全因死亡率、心血管疾病死亡率以及癌症死亡率中的任何一项均无相关性。研究的确发现蛋白质摄入量与糖尿病死亡率之间具有统计学显著相关性，但研究人员提醒说，由于该分析中纳入的人数过少，应谨慎对待由此得出的任何结果。

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.

而上面倒数第二段中那个可怕的结论只不过是一项仅考察50岁到65岁参与者的亚组分析的结果而已。如果你将调查的对象改为65岁以上的参与者，就会发现情况恰恰相反。高蛋白摄入量与较低的全因死亡率和癌症特异性死亡率相关。如果你相信这项研究为应该少吃红肉提供了证据，那么我们也应该建议65岁以上的人多吃些肉——显然并没有人这么做。

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，这项研究对“高蛋白质”组成员的定义为：饮食总热量中有至少20%来自蛋白质。考虑到美国农业部(United States Department of Agriculture,USDA)建议美国人从蛋白质获得的热量应占所需热量的10%至35%，20%其实不能算高。

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.

如果允许我自己来挑选的话，我也能找出一项2013年的研究，它使用了相同的Nhanes数据，却得出了相反的结论：肉类消费量与死亡率毫不相关。

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.

不过，我们还是不要刻意去挑选吧。2013年的一项关于肉类膳食研究的荟萃分析纳入了上述的几类情况，分析结果发现：与红肉消费量最低组相比，最高组成员的全因死亡率增加了29%，但这一增加主要是由加工肉类，如培根、腊肠或意大利香肠等造成的。

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.

流行病学证据能告诉我们的也只有这么多了。正如我之前所说，这类研究有可能存在缺陷。2012年的一项典型的系统性综述就是最好的佐证：该综述表明，几乎我们的所有食物都同时与较高和较低的癌症发病率相关。

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，我们需要进行随机对照试验才能真正找到问题的答案。这样的实验确实是存在的，不过却是关于胆固醇和甘油三酯等血脂水平指标的。一项荟萃分析审查了八项试验，发现与食用禽肉和鱼肉相比，食用牛肉并不会显著改变人的胆固醇或甘油三酯水平。

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，所有这些都忽略了更重要的一点——“太多”的标准到底是什么。红肉消费量最高组的人每天食用一至两份红肉，而最低组的人每周才食用大约两份。如果你每天都吃好几份红肉，那么，没错，你是需要控制一下了。但我敢打赌，正在阅读这篇文章的人中大多数都不会吃那么多。如果你每周食用一两份红肉，那么最有可能的情况是：你的身体一切正常。

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.

健康警告大大改变了我们的饮食习惯。美国人今天的红肉消费量比20世纪70年代以来的任何时候都少。人们并没有忽略医生的建议。我们在食用蔬菜方面也取得了一点进步。但我们对谷物和糖等碳水化合物的消费量却一直在上升。在某种程度上，可以说这正是我们执着于不吃脂肪和红肉的后果。

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.

我们仍然摄入了太多的热量，只不过改了个途径罢了。最明智的做法应该是以平衡的方式少吃那些我们过量食用的东西才对。

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，《美国医学协会杂志》(Journal of the American Medical Association)上发表了一项对著名饮食方案的荟萃分析。该研究既比较了单个的饮食方案，也对三大类饮食方案：低碳水化合物饮食（如阿特金斯饮食法[Atkins]），中度宏量营养素饮食（如Weight Watcher）和低脂肪饮食（如Ornish饮食）进行了比较。所有的饮食方案都减少了热量摄入，它们都能令参与者在六个月后体重减轻，并在接下来的六个月里继续减轻（但减重幅度较小）。它们之间并没有表现出明显的优劣。

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.

这给我们带来什么启示？你最有可能坚持下来的饮食方案就是最好的饮食方案——世界上最棒的教益或许莫过于此。把健康状况不佳归咎于某一特定的营养物质，并宣称其他人的饮食习惯都不对，这样做没有一点好处。很显然，任何时候任何人这么做都是毫无根据的。