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

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from soil moisture and ice caps,

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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,

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age,

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and sex,

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the average human is between 55-60% water.

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At birth, human babies are even wetter.

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

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

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So what role does water [br]play in our bodies,

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

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

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regulate temperature,

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and to nourish the brain and spinal cord.

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Water isn't only in our blood.

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

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

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Lungs are more similar to an apple at 83%.

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And even seemingly dry human bones[br]are 31% water.

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If we are essentially made of water,

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and surrounded by water,

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why do we still need to drink so much?

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

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urine,

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and bowel movements,

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and even just from breathing.

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While these functions [br]are essential to our survival,

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we need to compensate for the fluid loss.

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Maintaining a balanced water level[br]is essential to avoid dehydration

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or over-hydration,

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both of which can have devastating[br]effects on overall health.

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At first detection of low water levels,

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sensory receptors [br]in the brain's hypothalamus

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signal the release [br]of antidiuretic hormone.

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When it reached the kidneys, [br]it creates aquaporins,

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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.

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Increased dehydration can cause[br]notable drops in energy,

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

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skin moisture,

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and blood pressure,

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as well as signs of cognitive impairment.

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A dehydrated brain works harder [br]to accomplish the same amount

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as a normal brain,

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and it even temporarily shrinks[br]because of its lack of water.

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Over-hydration, or hyponatremia,

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

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Athletes are often the victims [br]of over-hydration

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because of complications [br]in regulating water levels

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in extreme physical conditions.

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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,

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possibly causing headache,

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vomiting,

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and, in rare instances, seizures[br]or death.

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

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On a normal, day-to-day basis,

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maintaining a well-hydrated system[br]is easy to manage

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

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

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That estimate has since been fine-tuned.

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

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depends largely on our weight[br]and environment.

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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,

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active,

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old,

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or overheating.

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While water is the healthiest hydrator,

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

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even those with caffeine [br]like coffee or tea,

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

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

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Fruits and vegetables like strawberries,

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cucumbers,

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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,

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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,

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think,

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