from soil moisture and ice caps,

從土壤濕度、冰帽、

to the cells inside our own bodies.

到我們體內的細胞，都有水的存在

Depending on factors like location,

根據因素的不同，像是地點、

fat index,

脂肪指數、

age,

年齡、

and sex,

和性別，

the average human is between 55-60% water.

一般人體內約有55%至60%是由水組成

At birth, human babies are even wetter.

出生時，人類嬰兒體內的水分甚至更多

Being 75% water, they are swimmingly similar to fish.

他們體內約有75%是由水組成，和魚差不多

But their water composition drops to 65% by their first birthday.

但當他們滿一歲時，體內的水成分降到65%

So what role does water play in our bodies,

到底水在我們體內是扮演什麼角色？

and how much do we actually need to drink to stay healthy?

而我們到底需要喝多少水來維持健康呢？

The H20 in our bodies works to cushion and lubricate joints,

我們體內的一氧化二氫（水的化學別名），負責緩衝和潤滑關節、

regulate temperature,

調節溫度、

and to nourish the brain and spinal cord.

以及滋養大腦和脊髓

Water isn't only in our blood.

水不只存在我們的血液中

An adult's brain and heart are almost three quarters water.

一個成年人的大腦和心臟加起來，幾乎有四分之三由水組成

That's roughly equivalent to the amount of moisture in a banana.

大約相當於一根香蕉所含的水分

Lungs are more similar to an apple at 83%.

肺臟裡的水分有83%，和一顆蘋果類似

And even seemingly dry human bones are 31% water.

甚至表面上看來乾枯的人類骨頭，都還有31%的水分

If we are essentially made of water,

假如我們基本上是由水做的，

and surrounded by water,

而且被水包圍著，

why do we still need to drink so much?

為什麼我們仍然需要喝這麼多水呢？

Well, each day we lose two to three liters through our sweat,

那是因為我們每天經由流汗、

urine,

排尿、

and bowel movements,

排便、

and even just from breathing.

甚至只透過呼吸，都會流失二到三公升的水分

While these functions are essential to our survival,

儘管這些功能對我們的生存至關重要，

we need to compensate for the fluid loss.

我們還是需要補充液體的流失

Maintaining a balanced water level is essential to avoid dehydration

維持平衡的水位，必須要避免脫水

or over-hydration,

或攝取過多水分

both of which can have devastating effects on overall health.

兩者對於整體的健康都有很大的殺傷力

At first detection of low water levels,

在第一次檢測到低水位時，

sensory receptors in the brain's hypothalamus

大腦下丘腦的感覺受體

signal the release of antidiuretic hormone.

會發出釋放抗利尿激素的訊號

When it reached the kidneys, it creates aquaporins,

當訊號抵達腎臟時，它會產生水通道蛋白（亦稱水孔蛋白），

special channels that enable blood to absorb and retain more water,

是種特殊的管道能讓血液吸收並保留更多的水份，

leading to concentrated, dark urine.

最後形成濃縮深色的尿

Increased dehydration can cause notable drops in energy,

脫水情況加重可引起精力明顯的減少、

mood,

心情變糟、

skin moisture,

皮膚水分減少、

and blood pressure,

和血壓變低、

as well as signs of cognitive impairment.

以及出現認知障礙的跡象

A dehydrated brain works harder to accomplish the same amount

脫水的大腦，比起正常的大腦，得更努力，

as a normal brain,

才能達成一樣的目標，

and it even temporarily shrinks because of its lack of water.

而且因為缺水的關係，大腦還會暫時萎縮

Over-hydration, or hyponatremia,

水分攝取過多，或者低血納症，

is usually caused by overconsumption of water in a short amount of time.

通常是由於短時間內攝取過多水分所造成

Athletes are often the victims of over-hydration

運動員往往是水分攝取過多的受害者

because of complications in regulating water levels

因為在極端的物理條件下，

in extreme physical conditions.

調節水位所引起的併發症的關係

Whereas the dehydrated brain amps up the production of antidiuretic hormone,

鑒於脫水大腦加強釋放抗利尿激素的量，

the over-hydrated brain slows, or even stops, releasing it into the blood.

水分過多的大腦反而放慢，甚至停止釋放激素到血液中

Sodium electrolytes in the body become diluted,

人體內的鈉電解質變得稀釋，

causing cells to swell.

造成細胞膨脹

In severe cases,

在嚴重的情況下，

the kidneys can't keep up with the resulting volumes of dilute urine.

腎臟無法負荷所產生的稀釋尿液量

Water intoxication then occurs,

就會發生水中毒

possibly causing headache,

可能導致頭痛、

vomiting,

嘔吐、

and, in rare instances, seizures or death.

以及，極罕見情況下，癲癇發作或死亡

But that's a pretty extreme situation.

但那是在非常極端的情形下才會發生

On a normal, day-to-day basis,

在一個正常的日常生活作息下，

maintaining a well-hydrated system is easy to manage

維持一個水分充足的系統是很輕而易舉的事，

for those of us fortunate enough to have access to clean drinking water.

尤其對於我們這些有幸取得乾淨飲用水的人來說

For a long time, conventional wisdom said that we should drink eight glasses a day.

長期以來，傳統的觀點認為我們每天應該要喝足八杯水

That estimate has since been fine-tuned.

這個估計已經有被調整過

Now, the consensus is that the amount of water we need to imbibe

現在的共識是，我們需要吸收的水量，

depends largely on our weight and environment.

大部分取決於我們的體重和所處的環境

The recommended daily intake varies from between 2.5-3.7 liters of water for men,

建議每日攝取量各有差異，男性需要2.5至3.7公升的水，

and about 2-2.7 liters for women,

而女性則需要2至2.7公升的水

a range that is pushed up or down if we are healthy,

水分攝取量可增多或減少，端視我們是否健康、

active,

活躍、

old,

老了、

or overheating.

或過熱

While water is the healthiest hydrator,

水是最健康的水化器，

other beverages,

其他的飲料，

even those with caffeine like coffee or tea,

即使是那些含有咖啡因的咖啡或茶，

replenish fluids as well.

也能補充液體

And water within food makes up about a fifth of our daily H20 intake.

食物裡的水分也占了我們每日一氧化二氫的攝取量的五分之一

Fruits and vegetables like strawberries,

水果和蔬菜，像是草莓、

cucumbers,

小黃瓜、

and even broccoli are over 90% water,

甚至是花椰菜，都含有超過90%的水分，

and can supplement liquid intake while providing valuable nutrients and fiber.

可以補足液體攝取量的同時，也提供了很有價值的營養和纖維

Drinking well might also have various long-term benefits.

喝得好也有各種長期的好處

Studies have shown that optimal hydration can lower the chance of stroke,

研究顯示最佳的保濕可以降低中風的機率，

help manage diabetes,

幫助管理糖尿病，

and potentially reduce the risk of certain types of cancer.

而且有可能減少某些類型癌症的風險

No matter what, getting the right amount of liquid makes a world of difference

不論如何，獲得適量的液體，

in how you'll feel,

對你每天的感受、

think,

想法、

and function day to day.

以及功能運作，會感到有天壤之別