Water is virtually eveywhere,
from soil moisture and ice caps,
to the cells inside our own bodies.
Depending on factors like location,
体脂 年龄 性别
fat index, age, and sex.
The average human is between 55-60% water.
At birth, human babies are even wetter.
Being 75% water,
they are swimmingly similar to fish.
But their water composition drops to 65%
by their first birthday.
So what role does water play in our bodies,
and how much do we actually need to drink
to stay healthy?
The H20 in our bodies works to cushion and lubricate joints,
regulate temperature, and to nourish the brain and spinal cord.
Water isn’t only in our blood.
An adult’s brain and heart are almost three quarters water.
That’s roughly equivalent to the amount of moisture in a banana.
Lungs are more similar to an apple at 83%.
And even seemingly dry human bones are 31% water.
If we are essentially made of water,
and surrounded by water,
why do we still need to drink so much?
Well, each day we lose two to three liters
through our sweat, urine, and bowel movements,
and even just from breathing.
While these functions are essential to our survival,
we need to compensate for the fluid loss.
Maintaining a balanced water level is essential to avoid dehydration
both of which can have devastating effects on overall health.
At first detection of low water levels,
sensory receptors in the brain’s hypothalamus
signal the release of antidiuretic hormone.
When it reached the kidneys, it creates aquaporins,
special channels that enable blood to absorb and retain more water,
leading to concentrated, dark urine.
Increased dehydration can cause notable drops in energy,
mood, skin moisture,
and blood pressure,
as well as signs of cognitive impairment.
A dehydrated brain works harder to accomplish the same amount
as a normal brain,
and it even temporarily shrinks
Over-hydration, or hyponatremia,
is usually caused by overconsumption of water in a short of time
Athletes are often the victims of over-hydration
because of complications in regulating water levels
in extreme physical conditions.
Whereas the dehydrated brain amps up
含水量过高的大脑 迟钝 甚至会开始受损
the over-hydrated brain slows,
Sodium electrolytes in the body become diluted,
causing cells to swell.
In severe cases,
the kidneys can’t keep up with the resulting volumes of dilute urine.
Water intoxication then occurs,
possibly causing headache, vomiting,
and, in rare instances, seizures or death.
But that’s a pretty extreme situation.
On a normal, day-to-day basis,
maintaining a well-hydrated system is easy to manage
for those of us fortunate enough
to have access to clean drinking water.
For a long time, conventional wisdom said that
we should drink eight glasses a day.
That estimate has since been fine-tuned.
Now, the consensus is that the amount of water we need to imbibe
depends largely on our weight and environment.
The recommended daily intake varies
and about 2-2.7 liters for women,
a range that is pushed up or down
活动量 年龄 体温来调节
if we are healthy, active, old, or overheating.
While water is the healthiest hydrator,
even those with caffeine like coffee or tea,
replenish fluids as well.
And water within food makes up about
水果蔬菜 比如草莓 黄瓜
Fruits and vegetables like strawberries, cucumbers,
and even broccoli are over 90% water,
and can supplement liquid intake
Drinking well might also have various
Studies have shown that optimal hydration
help manage diabetes,
and potentially reduce the risk of
certain types of cancer.
No matter what, getting the right amount of liquid
makes a world of difference
in how you’ll feel, think,
and function day to day.