世界最强力咖啡：一杯就失眠

咖啡对于大多数人来说，是一种提神刺激的饮料，但时常也有人提到“今天咖啡喝多了，晚上失眠”的痛苦。那么，一天喝多少咖啡是合理的呢？很可惜，负责系统研究综述的国际生命科学学会专家在此未能提供一个简单粗暴的答案。欲知答案，请往下浏览文章。

世界最强力咖啡：一杯就失眠...

“Bring it!”

“拿来！”

That’s what a Los Angeles news anchor said earlier this month, in response to the announcement that “the world’s strongest coffee” is now available in the United States. The product is called Black Insomnia, a playful nod to a potentially debilitating medical condition that can be caused by the product.

这是一位新闻主播在本月初听闻“世界上最强力的咖啡现已在美国推出”后的回应。该产品被叫做“黑色失眠”，以一种玩笑的方式肯定了该饮料可能导致医学意义上的人体虚弱状态。

The anchor’s tone took a dramatic decrescendo as she read from the teleprompter: “The site Caffeine Informer says Black Insomnia is one of the ‘most dangerous caffeinated products.’” Her smile faded. “Oh. I’ll have to have this one sparingly.”

随着她望向提词器的目光，主播的声音戏剧性地渐低：“网站‘咖啡因通密探’称，‘黑色失眠’是‘最危险的咖啡因产品’之一。”她脸上的笑容消失了。“那我只能有节制地喝了。”

Black Insomnia is actually in competition for the title of “world’s strongest coffee.” Another, similar purveyor sells coffee grounds called Death Wish. They come in a black sack with a skull and cross bones. On its Amazon page, Death Wish claims to be “the world’s strongest coffee” and promises its “perfect dark roast will make you the hero of the house or office.”

实际上“黑色失眠”正在争夺“世界最强力咖啡”的头衔。另一家供应商售卖叫做“死亡之愿”的研磨咖啡，装在一个有骷髅头和交叉骨头的黑口袋里。在亚马逊的页面上，“死亡之愿”声称它是“世界最强咖啡”，并保证“完美的深度烘焙会让你成为公司或办公室里的英雄。”

How much caffeine is required for heroism? At what point does the drug (known technically as 1,3,7-trimethylxanthine) actually become unsafe?

要当英雄需要多少咖啡因？这种物质（其学名是1,3,7-三甲基黄嘌呤）在何种用量下会变得不安全？

Caffeine occurs in plant leaves and seeds as an insect repellant and herbicide. It is used in hospitals to revive newborns who stop breathing. It can be given intravenously to induce seizures. CNN cautioned against Black Insomnia: “Just one cup could spill you over the daily caffeine limit.”

咖啡因作为驱虫剂以及除草剂存在于植物叶子和果实中。在医院中，它也会被用来救治那些呼吸暂停的新生儿。静脉注射咖啡因会引发癫痫。CNN对“黑色失眠”提出警告：“一杯就会超过你一天的咖啡因摄入上限。”

Multiple news outlets referred to this “limit.” For healthy adults, the number is 400 milligrams per day, and it comes from sources like the Food and Drug Administration and the International Food Information Council. Four hundred milligrams amounts to around four cups of coffee in the old-style sense of the phrase, an eight-ounce mug in a diner. It’s more like one Starbucks venti.

多家新闻媒体都提起过该“上限”。对于健康成人来说，咖啡因摄入的上限是每日400毫克，该数据来源于食品药品管理局以及国际食品信息委员会。400毫克大概相当于旧式咖啡杯四杯的量，或者是餐厅里8盎司马克杯的一杯。差不多是星巴克大杯的样子。

When it comes to caffeine, a drug that’s part of the everyday lives of 90 percent of Americans and a source of great joy—sometimes the actual best part of waking up—that limit can seem less like an admonition than a challenge. Black Insomnia claims to have 702 milligrams of caffeine in a 12-ounce cup. That’s around five times as much as a home-brew, and three times as much as Starbucks’s dark roast. And no serious coffee drinker would stop at 12 ounces. Fill two venti cups with Black Insomnia and you’re at 2,340 milligrams, or about six times the “limit.”

咖啡是90%美国人日常生活的一部分，也是快乐的源泉，有时一杯咖啡是起床时的最大乐趣。因此，对于美国人来说，咖啡因摄入量的上限看起来不像是劝诫，倒更像是挑战。一杯12盎司的“黑色失眠”中含有702毫克咖啡因，基本上相当于家庭自制咖啡的五倍，星巴克深度烘焙咖啡的三倍。但没有哪个真正的咖啡饮用者会只喝12盎司就满足。喝下两大杯“黑色失眠”，你的咖啡因摄入量就达到了2340毫克，约等于“上限”的六倍。

With options like this before us, where does the 400 milligram limit come from, and how seriously should it be taken?

鉴于以上事实，我们不禁要问400毫克的摄入上限从何而来？我们到底应该多严肃的对待这个上限？

Esther Myers says seriously. She is a specialist in systematic research reviews, and over the past year she and colleagues at the International Life Sciences Institute have been working on the most exhaustive review of evidence on the safety of caffeine to date. This week the team is presenting the findings in Chicago at a conference called Experimental Biology.

埃斯特·迈尔斯认为这个上限很重要。她是系统研究综述领域的专家，过去的几年以来她和国际生命科学会的同事详尽考证了迄今为止所有与咖啡因安全性相关的材料。这周，埃斯特的团队在芝加哥一次名为“实验生物学”的会议上发布了研究成果。

Myers explained that the oft-cited 400-milligram limit has been out of date for a while. It came from the last research review, which was done in 2003 by Health Canada. Her colleagues were surprised to learn it had been that long, and that even at the time the review wasn’t really comprehensive. So they did a systematic review, meaning they followed a comprehensive, transparent protocol defined by the Institute of Medicine.

迈尔斯解释道，经常被引用的“400毫克上限”已经过时一段时间了。它来自于加拿大卫生部“最近”的研究综述，这一综述完成于2003年。她的同事对于此数据的久远感到非常惊讶，而就算在那个时候，该研究综述也并不能称得上非常全面严密。因此，他们进行了一次系统性的研究审查，这意味着他们遵循了由医学研究所拟定的全面透明的方法。

The team scoured more than 700 studies on the safety of caffeine at various levels and noted whether adverse health effects occurred above, below, or at 400 milligrams. Those health effects ranged spanned cardiovascular, musculoskeletal, reproductive, and behavioral domains. And it seems that for healthy adults, 400 milligrams is indeed a safe daily limit. For pregnant women, it’s safer to use 300 milligrams or less.

团队搜索了700余件关于咖啡因安全性在不同摄入量下的研究，并分别记录了每日摄入低于、等于或高于400毫克咖啡因时是否会出现不利的健康影响。这些健康影响囊括了心血管、肌肉骨骼、生殖以及行为领域。对于健康的成人来说，400毫克似乎是一个相当安全的限定。怀孕的女性摄入300毫克或以下会更安全。

Above those levels the team found evidence of links to everything from depression and dysphoria (general unhappiness) to anxiety to hypertension to higher proportions of sperm with DNA damage.

在每日摄入量超过400毫克的人群中，研究团队发现了咖啡因摄入与沮丧、烦躁不安（心境恶劣）、焦虑、高血压以及更高比例的精子DNA损伤都有联系。

So does that mean that 500 milligrams a day is definitely unsafe?

所以这是否意味着每日500毫克就一定是不安全的呢？

“No,” said Myers. “There’s a great deal of inter-individual variability in how people respond to caffeine. That’s one of the research gaps. We need to better identify differences and identify people who are more sensitive.”

“并不，”迈尔斯说。“人们对咖啡因的反应存在非常大的个体差异。”这是其中一个研究空白区。我们需要更好地识别差异，识别那些更为敏感的人。

The most important finding of this research was, apparently, how little we know for certain about this drug that’s all around us. Myers’s team highlights a particular need for a better understanding of how caffeine affects less-than-healthy adults. There is also much more to be determined about how the health effects of caffeine vary depending on how, when, and with what frequency it’s consumed. No matter how much we learn about caffeine, even as one of our most studied and consumed drugs, there will always be more questions.

这项研究最重要的结论就是，显然我们对身边的这个化学物质知之甚少。迈尔斯的团队认为，十分有必要深入研究咖啡因对亚健康人群的影响。仍亟待研究如何、何时、以何种频率摄入咖啡因对健康会有何种影响。无论我们对咖啡因这一我们研究得最详细、应用得最广泛的药物了解多少，仍有更多的问题有待解决。

My takeaway is that when a product is calling itself Black Insomnia or Death Wish, listen more and bring it less. Note doses in all caffeinated products and consider keeping track. Treat caffeine generally more like a drug than a challenge. In a food environment saturated with caffeine, the surest route to being a “hero of the house or office” is as an exemplar of moderation.我的结论是，当一个产品把自己称作“黑色失眠”或是“死亡之愿”时，多了解，少武断食用。把所有咖啡因产品中的咖啡因含量都记下来，监测你的摄入量。把咖啡因看作是一种药物，而不是一场挑战。在充满咖啡因的食物环境中，要做“公司或办公室中的英雄”最稳妥的路线还是成为一个自我节制的典范。