中英说健康丨咖啡到底喝多了会怎么样？为什么外国人喝那么多也没事。

今日内容提要：

关于喝咖啡好不好？喝多少为适量？什么是过量？一直是健康话题的热点。

这个话题有必要么？很有。

最近玲琅满目，层出不穷的咖啡店，再看看咖啡的种类，从简单的美式到现在越来越盛行的氮气咖啡，搞的跟啤酒像同父异母的兄弟一样，确实好喝。

喝多少为宜，喝多少能给你带来需要的帮助，今天我们分享的就是这个点。

我本人是每天1杯-3杯，很多老外是一天3-4杯，他们好像从来没在关心睡不睡的着这件事…为什么呢？

喝咖啡不存在“过量”的问题

First the good news.

It's almost impossible tooverdoseon coffee.

There is a lethal dose of caffeine but it's somewhere around 10 grams and the average cup of joe has around 100 milligrams.

我们先从好的说起。

咖啡几乎不可能摄取过量。

咖啡因社区达到一定程度确实会致命，但你得喝到10公克，我们一般喝的咖啡一杯只有100毫公克。 

You'd likely have to drink 100 cups in rapid succession to OD.

你大概得喝上100杯才算超量。

But that's not to say there's no such thing as too much.

The FDA recommends no more than four to five cups a day for the average healthy adult.

More than that and you might start to experience some nasty side effects.

不过这并不代表你可以想喝几杯就几杯。根据美国食品药品监督局建议，普通健康成年人一天不要超过四到五杯。

为什么我们要喝咖啡？

Most people take in coffee to increase their focus and concentration.

But once you take in too much you start to lose that focus.

People start getting more agitated, irritable.

大部分人喝咖啡是为了提高注意力，专注程度。

一旦喝太多，你反而会降低你的注意力。

人会变得躁动不安，易怒。 

That's thanks to the hormone, adrenaline.

When caffeine hits your system it stimulates your adrenal glands which release the hormone into your body, it makes you feel energetic and alert. 

这是因为肾上腺素这种荷尔蒙所导致的。当咖啡因开始发生作用，它会刺激肾上腺素，将荷尔蒙释放至体内，让你充满活力，提高警觉。

喝多了会怎样？

引起焦虑

But too much can be a bad thing.

Especially if you suffer from anxiety.

But with anxiety you also wanna be careful not to overstimulate or trigger any sort of panic attacks and make anxiety worse, which certainly too much caffeine can do.

但太多就是变成坏事。

特别是你在焦虑的时候。谈到焦虑症状，要小心不能过度刺激，不能诱发任何形态的恐慌感，让焦虑症恶化；而太多咖啡绝对会造成这种情况。 

心率不齐

Adrenaline from caffeine can also increase your heart rate.

That's why doctors also recommend against drinking coffee if your heart sometimes beats irregularly.

But the risk is really only for bona fide coffee junkies.

咖啡因激起的肾上腺素也可能使心跳加速。这就是为什么如果有什么心跳不规律的问题，医生会建议不要喝咖啡。

然而这样的风险只针对真正的咖啡上瘾者。 

According to at least two observational studies you have to drink at least nine cups of coffee a day to put yourself at risk of arrhythmia.

根据研究，你一天得喝超过九杯咖啡才可能让自己处于心率不齐的风险。 

影响睡眠

And finally, there's the question of sleep.

Coffee's enemy.

Caffeine launches a double threat on your slumber.

It blocks the neurochemical adenosine which is what tells your brain that you're tired.

It releases a cocktail of stimulants into your brain: adrenaline, dopamine, and glutamate.

最后还需要说到睡眠问题。

咖啡对睡眠很不利。

咖啡因对你的睡眠会产生双重威胁。

神经化学方面，咖啡因会抑制腺苷，当你疲累时腺苷会传讯给大脑。

咖啡因会释放出混合刺激物给大脑，包含肾上腺素，多巴胺，谷氨酸。 

So after donning your sixth cup of coffee, you don't just feel awake but full of energy. It will power you through that 2:30 meeting or the last class of the day.

因此六杯咖啡下肚以后，你不但十分清醒，而且活力满满。它能带你撑过下午两点半的会议，或者熬过最后一节课。

It's sort of just stuck in this loop where you're not sleeping because you drink too much coffee. And then you wake up in the morning and you're not well rested and you're drinking more coffee just to stay awake in the day.

你会困在一种循环：喝太多咖啡因而睡不好。隔天早上起来休息不够，所以喝更多咖啡来撑过这天。

喝咖啡难道没有好处么？

Here's the good news.

If you cut yourself off by 2:00 p.m, you typically won't have trouble falling asleep. That's because the half-life of caffeine is around five hours.

And so most of its stimulating effects will wear off well before the lights go out.

好消息来了。只要在下午两点以后不碰咖啡，你基本上是不会有睡眠问题的。这样晚上关灯睡觉前，大部分的刺激效果就会消退。

And if you also limit your consumption, well then coffee can actually offer a number of health benefits.

Research shows that it can help with everything from memory, to exercise, to your relationships with your colleagues.

And that's great because for some of us, coffee is just something we'll just never give up.

而且如果你有在注意摄取量的话，事实上咖啡会带来不少健康益处。研究结果显示咖啡对你的记忆，运动效果，职场关系都有帮助。这真是太好了，因为对某些人来说，咖啡可是我们永远不想放弃的东西。

喝咖啡指南

一日不超过4-5杯

下午2点后不喝咖啡

超过9杯会引起心率不齐

对记忆有好处

对运动有帮助

对职场关系好