0:00:06.505,0:00:08.807
Water is virtually eveywhere,

0:00:08.807,0:00:11.259
from soil moisture and ice caps,

0:00:11.259,0:00:14.086
to the cells inside our own bodies.

0:00:14.086,0:00:16.181
Depending on factors like location,

0:00:16.181,0:00:17.399
fat index,

0:00:17.399,0:00:18.114
age,

0:00:18.114,0:00:19.202
and sex,

0:00:19.202,0:00:23.808
the average human is between 55-60% water.

0:00:23.808,0:00:27.024
At birth, human babies are even wetter.

0:00:27.024,0:00:32.307
Being 75% water, [br]they are swimmingly similar to fish.

0:00:32.307,0:00:37.331
But their water composition drops to 65%[br]by their first birthday.

0:00:37.331,0:00:40.196
So what role does water [br]play in our bodies,

0:00:40.196,0:00:44.288
and how much do we actually need to drink[br]to stay healthy?

0:00:44.288,0:00:48.529
The H20 in our bodies works to cushion[br]and lubricate joints,

0:00:48.529,0:00:49.948
regulate temperature,

0:00:49.948,0:00:53.932
and to nourish the brain and spinal cord.

0:00:53.932,0:00:56.062
Water isn't only in our blood.

0:00:56.062,0:01:00.510
An adult's brain and heart are almost[br]three quarters water.

0:01:00.510,0:01:04.367
That's roughly equivalent to the amount[br]of moisture in a banana.

0:01:04.367,0:01:08.487
Lungs are more similar to an apple at 83%.

0:01:08.487,0:01:14.310
And even seemingly dry human bones[br]are 31% water.

0:01:14.310,0:01:16.051
If we are essentially made of water,

0:01:16.051,0:01:17.634
and surrounded by water,

0:01:17.634,0:01:20.492
why do we still need to drink so much?

0:01:20.492,0:01:24.293
Well, each day we lose two to three liters[br]through our sweat,

0:01:24.293,0:01:25.227
urine,

0:01:25.227,0:01:26.707
and bowel movements,

0:01:26.707,0:01:28.371
and even just from breathing.

0:01:28.371,0:01:30.859
While these functions [br]are essential to our survival,

0:01:30.859,0:01:33.306
we need to compensate for the fluid loss.

0:01:33.306,0:01:37.848
Maintaining a balanced water level[br]is essential to avoid dehydration

0:01:37.848,0:01:39.710
or over-hydration,

0:01:39.710,0:01:43.279
both of which can have devastating[br]effects on overall health.

0:01:43.279,0:01:45.404
At first detection of low water levels,

0:01:45.404,0:01:48.367
sensory receptors [br]in the brain's hypothalamus

0:01:48.367,0:01:51.399
signal the release [br]of antidiuretic hormone.

0:01:51.399,0:01:54.489
When it reached the kidneys, [br]it creates aquaporins,

0:01:54.489,0:02:00.445
special channels that enable blood[br]to absorb and retain more water,

0:02:00.445,0:02:03.050
leading to concentrated, dark urine.

0:02:03.050,0:02:06.555
Increased dehydration can cause[br]notable drops in energy,

0:02:06.555,0:02:07.586
mood,

0:02:07.586,0:02:08.774
skin moisture,

0:02:08.774,0:02:10.198
and blood pressure,

0:02:10.198,0:02:13.252
as well as signs of cognitive impairment.

0:02:13.252,0:02:17.210
A dehydrated brain works harder [br]to accomplish the same amount

0:02:17.210,0:02:18.696
as a normal brain,

0:02:18.696,0:02:22.618
and it even temporarily shrinks[br]because of its lack of water.

0:02:22.618,0:02:25.614
Over-hydration, or hyponatremia,

0:02:25.614,0:02:30.669
is usually caused by overconsumption[br]of water in a short amount of time.

0:02:30.669,0:02:33.242
Athletes are often the victims [br]of over-hydration

0:02:33.242,0:02:36.585
because of complications [br]in regulating water levels

0:02:36.585,0:02:39.263
in extreme physical conditions.

0:02:39.263,0:02:43.769
Whereas the dehydrated brain amps[br]up the production of antidiuretic hormone,

0:02:43.769,0:02:49.174
the over-hydrated brain slows,[br]or even stops, releasing it into the blood.

0:02:49.174,0:02:51.980
Sodium electrolytes in the body[br]become diluted,

0:02:51.980,0:02:54.133
causing cells to swell.

0:02:54.133,0:02:55.584
In severe cases,

0:02:55.584,0:02:59.768
the kidneys can't keep up with [br]the resulting volumes of dilute urine.

0:02:59.768,0:03:01.923
Water intoxication then occurs,

0:03:01.923,0:03:03.559
possibly causing headache,

0:03:03.559,0:03:04.688
vomiting,

0:03:04.688,0:03:08.162
and, in rare instances, seizures[br]or death.

0:03:08.162,0:03:10.295
But that's a pretty extreme situation.

0:03:10.295,0:03:12.062
On a normal, day-to-day basis,

0:03:12.062,0:03:15.632
maintaining a well-hydrated system[br]is easy to manage

0:03:15.632,0:03:19.528
for those of us fortunate enough [br]to have access to clean drinking water.

0:03:19.528,0:03:23.808
For a long time, conventional wisdom said[br]that we should drink eight glasses a day.

0:03:23.808,0:03:26.453
That estimate has since been fine-tuned.

0:03:26.453,0:03:30.245
Now, the consensus is that the amount[br]of water we need to imbibe

0:03:30.245,0:03:33.116
depends largely on our weight[br]and environment.

0:03:33.116,0:03:39.616
The recommended daily intake varies from[br]between 2.5-3.7 liters of water for men,

0:03:39.616,0:03:42.802
and about 2-2.7 liters for women,

0:03:42.802,0:03:46.148
a range that is pushed up [br]or down if we are healthy,

0:03:46.148,0:03:46.987
active,

0:03:46.987,0:03:47.950
old,

0:03:47.950,0:03:49.663
or overheating.

0:03:49.663,0:03:51.522
While water is the healthiest hydrator,

0:03:51.522,0:03:52.617
other beverages,

0:03:52.617,0:03:55.230
even those with caffeine [br]like coffee or tea,

0:03:55.230,0:03:57.323
replenish fluids as well.

0:03:57.323,0:04:02.306
And water within food makes up [br]about a fifth of our daily H20 intake.

0:04:02.306,0:04:04.333
Fruits and vegetables like strawberries,

0:04:04.333,0:04:05.302
cucumbers,

0:04:05.302,0:04:08.874
and even broccoli are over 90% water,

0:04:08.874,0:04:14.119
and can supplement liquid intake while[br]providing valuable nutrients and fiber.

0:04:14.119,0:04:17.276
Drinking well might also have various[br]long-term benefits.

0:04:17.276,0:04:21.618
Studies have shown that optimal hydration[br]can lower the chance of stroke,

0:04:21.618,0:04:23.107
help manage diabetes,

0:04:23.107,0:04:27.871
and potentially reduce the risk[br]of certain types of cancer.

0:04:27.871,0:04:32.051
No matter what, getting the right amount[br]of liquid makes a world of difference

0:04:32.051,0:04:33.338
in how you'll feel,

0:04:33.338,0:04:34.205
think,

0:04:34.205,0:04:36.073
and function day to day.