Why you don't need 8 glasses of water a day | Body Stuff with Dr. Jen Gunter | TED

Transcriber:

You know that whole thing about drinking eight glasses of water a day?

翻译人员: Alvin Lee 校对人员: Yanyan Hong

你肯定听过 “一天要喝8杯水” 这种说法吧？

Sorry to have to tell you this, but it's a myth.

很遗憾地告诉你，这就是个谣言。

It won't make your skin brighter,

它不会让你皮肤变好，

it won't make you feel clearheaded,

不会让你思路清晰，

it won't make you feel more energetic.

也不会让你觉得精力充沛。

It might, however, make you have to pee a lot.

倒是很有可能让你多跑几次厕所。

(Music)

（音乐）

[Body Stuff with Dr. Jen Gunter]

【与珍·冈特博士（Dr. Jen Gunter） 谈谈身体的那些事儿】

(Music)

（音乐）

很多人不了解自己身体 背后的生物学知识，

Many people don't understand the biology behind their bodies.

There's a lot of misinformation out there.

错误的信息满天飞。

But the truth is that when you understand how your systems function,

但一旦你了解了身体是如何运作的，

you're able to make better decisions.

你就能做出更好的决定。

You're not as prone to fall for hype or pseudoscience.

不会轻易掉入 虚假宣传和伪科学的陷阱，

You'll feel empowered to understand what's really going on.

你就能更好地理解你的身体。

One myth that really bugs me

有一个谣言让我真的不爽，

is the idea that you need eight glasses of water a day.

就是你每天需要喝 8 杯水。

Honestly, it's pretty shocking how ingrained it is.

实话说，这谣言真的流传甚广。

You hear it on TV, you see it in articles.

电视里有人讲，文章里有人写。

But like I said, it's nonsense.

但像我刚刚说的，这完全是瞎扯。

For the most part,

绝大部分情况下，

your body will tell you when you need to drink water,

你的身体会提醒你该喝水了，

because you've got these wonderful, amazing, undervalued things --

因为你有一件奇妙的、 神奇的、被大大低估的东西，

你的肾。

kidneys.

肾脏长得像豌豆， 位于你脊柱的两侧，

Kidneys are the bean-shaped organs located to either side of your spine,

right below your ribs.

肋骨下面一点点。

They're often thought of as a filter or a waste-removal system,

它们经常被认为是过滤器 或者垃圾清除系统，

but that doesn't do the kidneys justice.

但这还不能完全描述肾脏的作用。

Your body is an environment where everything, fluid and chemicals,

你的身体是一个需要保持精妙平衡的环境，

needs to be in a delicate balance.

无论是体液还是化学物质。

The kidneys do a lot of the heavy lifting when it comes to this balance.

而肾脏在维持这种平衡的过程中 发挥了重要作用。

Every day, blood in your body passes through the kidneys.

每天你身体里的血液都要经过肾脏。

What you eat, drink, the temperature around you,

你每天吃的、喝的， 你所处的环境温度，

how much you exercise --

你的运动量，

all of this affects what's going on with your body.

所有这些都会影响你的身体。

Your kidneys, along with your nervous system and various hormones,

你的肾脏，连同你的神经系统 和多种荷尔蒙一起，

are constantly watching many gauges

时刻监测并调整

and making adjustments about fluid, salt and levels of other substances

你的体液、盐分和其他物质的水平，

in real time.

都是实时的。

They do this with about one million tiny structures called nephrons.

肾脏通过一百万个微小的结构 来完成上述工作，

这种微小结构叫肾元。

These nephrons are kind of like workers on a conveyor belt,

肾元有点像流水线旁的工人，

actively adding things and taking things away,

不停地往里加点什么或者拿走点什么，

things like sodium, glucose or sugar, calcium, amino acids and water,

比如纳、葡萄糖或者糖， 钙、氨基酸和水，

to make sure the body maintains homeostasis, or balance.

保证身体处于平衡的状态。

If levels of anything get too high or too low,

如果任何东西过多或者过少，

then that can be harmful.

都是有害的。

And it is the job of the kidneys

肾脏的作用

to keep the levels of many of these substances in the just-right zone.

就是将多种物质的含量 保持在恰当的区间内。

Substances that aren't needed leave the kidney

不需要的物质就会离开肾脏，

and head to the bladder,

流向膀胱，

where you excrete them in the form of urine.

在那里以尿液的形式排出体外。

So where do eight glasses of water a day fit in?

这中间哪一步需要一天 8 杯水呢？

They don't.

哪都不需要。

Noticed that I did not say

请注意我刚刚并没有说

that the kidney function is improved with excess water.

肾功能会因为额外的水份而得到改善。

Imagine that you're sweating a lot,

想象一下，你出了很多汗，

so you're losing water from your blood.

因此你血液里的水份减少了。

The kidneys know your blood volume is dropping ever so slightly

你的肾脏注意到你的血量 下降了一点点，

and that your blood is getting ever so slightly saltier.

因此导致血液里的含盐量 上升了一点点。

They compensate by absorbing more water back into the blood,

它们会通过多吸收一些水 回血液来进行补偿，

making the urine more concentrated.

这样会导致你的尿更浓一些。

If the kidneys sense enough fluid can't be reabsorbed from the urine,

如果肾脏发现尿液里的水 也不够它们重新吸收的，

you're signaled to drink, meaning you get thirsty.

它们就会提醒你喝水， 这时你就会觉得渴。

If you don't have fluid available,

如果你没有喝水的话，

the thirst message gets stronger and stronger.

这种口渴的感觉就会越来越强烈。

A person facing real dehydration won't be unsure if they need water.

一个真的面临脱水状况的人，

是不可能拿不准自己是不是需要水的。

They'll do whatever they need to get it.

他们会想尽一切办法去搞到水。

It's one of our most basic instincts

这是我们最基础的本能之一，

that's evolved over a very long time,

是经历了漫长的进化过程得来的，

in environments where clean water

当时的环境并不像今天，

wasn't nearly as readily available as it is today.

清洁的水唾手可得。

So thanks to your kidneys,

因此多亏你的肾脏，

your body is really good at maintaining hydration.

你的身体才会非常善于保持水份充足的状态。

But if you stop counting eight glasses of water a day,

但是如果一天不需要喝8杯水，

how much should you be drinking?

那到底应该喝多少呢？

The answer is simple:

答案很简单，

there is no should.

没有定量。

When you feel thirsty, drink some water.

你什么时候觉得渴了，就去喝点水。

You can trust your body.

你可以相信自己的身体。

Unless you have kidney stones or are elderly --

除非你有肾结石，或者年纪大了，

sometimes, our messaging systems get a little worn with age --

有时候我们的信息传递系统 会随着年龄增长变迟钝，

or your doctor has told you otherwise,

又或者你的医生有吩咐，

constantly monitoring how much water you drink

否则，持续监测自己喝了多少水，

is not really necessary.

真的完全没必要。

Here's a point that's often missed:

还有一点经常被忽视：

every single thing you consume contains water.

你吃的每一样食物都含有水。

Your morning coffee has water, so does your breakfast.

你早上的咖啡里有水， 你的早餐里也含水。

And that snack -- an apple, an orange, a glass of juice, a granola bar --

你的零食——无论是苹果、 橙子、一杯果汁、一个燕麦卷——

just like you, they're made of water too.

就像你自己一样，它们都是由水构成的。

So as long as you're listening to your body's internal sense of thirst,

所以只要你听从身体里发出的口渴的信号，

there's really no need to be counting those eight glasses.

每天数着喝 8 杯水真的没必要。