酒精之好会胜过酒精之害吗？

前言：本视频是2018年4月6号刚刚发布的，是在NutritionFacts.org的YouTube频道发布的，NutritionFacts.org网站上暂时还没有。

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摘要：如果把在一生时间内天生多饮酒或少饮酒的人正确地随机分组会得出什么结果呢？他们会相应得到多或少的心脏病吗？

https://v.qq.com/txp/iframe/player.html?vid=s0637007nj5&width=500&height=375&auto=0

一旦从有关酒精和死亡率的研究中删除将曾饮酒者误归类为终生戒酒者的系统错误，像一天一杯葡萄酒这样的适度饮酒习惯，似乎就变得并没有什么保护作用了。

Once you remove from studies on alcohol and mortality the systematic error of misclassifying former drinkers as if they were lifelong abstainers, moderate alcohol consumption, like a glass of wine a day, does not appear to be protective after all.

这项新研究的直接意义是临床医生需要高度怀疑其假设的饮酒所带来的健康益处并且不应建议其患者通过喝酒来延长寿命。

The immediate implication from this new research is that clinicians need to be highly skeptical about the hypothesized health benefits of alcohol consumption and should not advise their patients to drink to improve their life expectancy.

鉴于越来越多人认识到适量饮酒将带来癌症风险，这一点因此就显得尤为重要了。

This is especially important given increasing awareness of cancer risks from even moderate alcohol use.

对于癌症风险而言，若只有危害而没有益处的话，那么理想的日常饮酒量应该为零，使酒精成为一种红灯类型饮料。（红灯为最不健康的类别）

Given the cancer risk, if there's just harms and no benefits, then the ideal alcohol intake on a routine day-to-day basis should really be zero, potentially making it a red-light beverage.

问题是很多研究都把为了健康而戒酒的人分类成非饮酒者。这是因果关系颠倒的问题：不是戒酒导致身体不好，而是身体不好导致的戒酒。

The problem was that many of these population studies classified those that quit drinking in response to ill-health as non drinkers. This is the problem of reverse causation: instead of abstaining leading to poor health, poor health may have lead to abstaining.

就像研究表明那些久坐看电视的人身体更不好一样。是电视看得多导致的患病，还是因为身体不好才导致久坐看电视的行为呢？

It's like when studies show those who sit around and watch TV have worse health. Is more TV leading to illness, or is illness leading to more TV on the couch?

作为原因之一，当你关注证据层次时，金字塔较高之处意味着更强的证据，像随机对照实验这样的介入性实验往往能比人群观察性研究提供更佳的证据，因后者可能会遭受反向因果和混杂因素的双重影响。

That's one of the reasons why if you look at the hierarchy of evidence, where higher on the pyramid means stronger evidence, interventional trials, like randomized controlled trials, tend to offer better evidence than observational studies of populations, which can suffer from both reverse causation and confounding factors.

例如，轻度饮酒者们可能在喝葡萄酒时更可能搭配沙拉而非芝士汉堡，而这就是喝酒貌似具有保护性的原因。

For example, light drinkers as a group may be more likely to drink their glass of wine with a salad than a cheeseburger, and that's why the wine appeared protective.

但有时，做随机对照实验是有难度的，正如你无法随机让一群人几十年间每天抽一包烟一样。

But sometimes it's hard to do randomized controlled trials, like you can't randomize people to smoke a pack a day for a few decades.

所以有时你必须在观察性研究的基础上做决定。

So sometimes you have to base your decisions on observational studies.

但现在我们有了一个新工具，即孟德尔随机化法。

But now we have a new tool, Mendelian randomization.

在随机对照实验不可行或不切实际的情况下，该新工具可提供关于暴露（比如饮酒、吸烟等）与疾病风险之间的因果关系的可靠证据。

In cases where randomized controlled trials are not feasible or practical, this new tool can provide reliable evidence on the cause and effect relationship between exposures and risks of disease.

这和HDL（高密度胆固醇）故事所说的一样。

It's like the HDL story.

酒精确实会提高HDL，即“好”的胆固醇水平。但很不幸，似乎好的胆固醇在降低心脏病风险方面并无好处。

Alcohol does raise your HDL 'good' cholesterol levels. But unfortunately, it seems good cholesterol isn't any good at lowering heart disease risk after all.

此结论部分基于孟德尔随机化研究， 出生就有基因决定的高HDL水平，而被随机分到更高HDL水平组的人，似乎并未因此受到保护。（译注：即使有较高HDL，心脏病发病率并未因此降低。）

Based in part on Mendelian randomization studies, where people who were randomly assigned higher HDL levels genetically from birth don't appear to be protected.

有没有什么方法能够研究那些天生不喝酒（译注：如前所述是基因决定不能喝酒），而被随机分配到“喝少量酒组”的人呢？

Is there any way to study people who are randomly assigned since conception to not drink as much?

非常不可思议的是，还真的有啊。

Remarkably, yes.

酒精在肝脏中被两种酶分解成二氧化碳和水，但在此过程中将会产生一种有毒的中间代谢产物，即可能引起不愉快的恶心感和潮热感的乙醛。

Alcohol is detoxified in the liver to carbon dioxide and water by two enzymes. But in the process, a toxic intermediate metabolite is produced called acetaldehyde, which can cause unpleasant nausea and flushing sensations.

所以如果人们生来就拥有此酶的缓慢变体，或是此酶的超快变体，那么乙醛就可能累积起来，使喝酒在这些人的一生中成为一种相对而言不愉快的经历。

So if people are born with a slow variant of this enzyme, or a superfast variant of this enzyme, acetaldehyde can build up, making alcohol drinking in these people a relatively unpleasant experience throughout their lives.

所以他们自打出生就不太能喝酒。

So they're just born less likely to drink as much.

那么他们会不会有更高的患心脏病风险，就像原观察性研究所表明的呢？

So do they have an increased risk of heart disease, like the original observational studies would suggest?

不，他们心脏病风险较低。

No, they have reduced risk of heart disease.

这意味着即使是对于轻中度饮酒者而言，降低酒精摄入量都是对心血管健康有益的。

This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health.

而这正是对“适量”饮酒对于心脏病具有保护作用的一种进一步怀疑，而这种保护作用已经被各种混杂和偏见信息所困扰了。

So this just sheds further doubt on the protective association between 'moderate' alcohol consumption and heart disease, which was already plagued with the confounding and bias.

目前该作用所基于的科学支柱已日益摇摇欲坠，导致一些假定“适度”饮酒将对健康有益的倾斜之塔最终崩塌。

And now the scientific pillars on which it's based appear increasingly shaky, leading some to suggest the leaning tower of presumed health benefits from 'moderate' alcohol use has finally collapsed.

鉴于由酒精带来的危害，不难想象为何那些指出酒精益处的报告能让消费者、媒体，当然还有酒精行业如此热衷，但这些所谓的益处正在消失中。

Given the harms attributed to alcohol use, it is not surprising that reports suggesting benefits attracted enthusiasm among consumers, the media, and, of course, the alcohol industry, but these apparent benefits are now evaporating.

我们应该从这些新出现的证据得出什么结论呢？

What conclusions should we draw from this emerging evidence?

首先，健康和其它方面一样，如果某些事情看上去好到不真实 — 比如黄油很健康 — 那就应该非常小心啦。

First, in health as elsewhere, if something looks too good to be true — like butter is back — it should be treated with great caution.

第二，健康专业人士不应该鼓励喝酒。

Secondly, health professionals should discourage drinking.

第三，健康相关建议应来自卫生部门，而不是酒精行业，从而应该去除所有具有误导性的支持酒精有益健康的资料，这些资料看起来更像是公关专家的战绩而非权威科学的胜利，就像石油工业所推动的科学家在气候变迁方面的所谓分歧一样。

Thirdly, health advice should come from health authorities, not from the alcohol industry, which should remove all misleading references to purported health benefits, which are increasingly looking more like a triumph of spin doctoring than good science, as contrived as the alleged split among scientists over climate change, advanced by the petroleum industry.

作为一个令人沉迷的、上瘾的、有毒的、致癌药物，酒精并非是作为治疗剂的好选择，即使真的有帮助。

As an intoxicating, addictive, toxic, carcinogenic drug, alcohol is not a great choice as a therapeutic agent, even if it did help.

预防心脏病可用更好的方式，比如饮食和运动，必要时也可使用药物。

There are better ways to prevent heart attacks, namely diet and exercise, and drugs when necessary.

与酒精正相反，生活方式干预的有效性已被证实，额外的好处是，不会有上瘾滥用的可能。

In contrast to that of alcohol, effectiveness of lifestyle interventions has been demonstrated, and as a bonus has no abuse potential.

你总没听过有“匿名戒苹果会”这种东西吧？

There's a reason there's no Appleholics Anonymous.

（译注：与“匿名戒酒会”Alcoholic Anonymous 对比，Michael Greger 医生好幽默！超级喜欢这位治学严谨，演讲抑扬顿挫、幽默风趣的医生！）

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阅读往期相关文章：

酒精会致癌吗？2018年3月28日 发布

喝一点酒比滴酒不沾更好吗？2018年4月4日发布

特别推荐符合 “低脂全蔬食” 原则的健康食谱公众号：

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关于编译者：老玉米是美国康奈尔大学坎贝尔营养研究中心《蔬食营养》证书持有者。老玉米的先生是美国内科医生（MD），也是位“蔬食医生”（Plantrician）。

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