Water is essentially everywhere in our world, and the average human is composed
of between 55 and 60% water. So what role does water play in our bodies,
and how much do we actually need to drink to stay healthy?
Water is virtually everywhere, from soil moisture and ice caps, to the cells inside
our own bodies. Depending on factors like location, 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 or over-hydration, 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 because of its lack of water. Over-hydration, or hyponatremia,
is usually caused by overconsumption of water in a short amount 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 the production of antidiuretic hormone,
the over-hydrated brain slows, or even stops, releasing it into the blood.
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 from between 2.5-3.7 liters of
water for men, and about 2-2.7 liters for women, a range that is pushed up
or down if we are healthy, active, old, or overheating. While water is the
healthiest hydrator, other beverages, even those with caffeine like coffee
or tea, replenish fluids as well. And water within food makes up about a fifth
of our daily H20 intake. Fruits and vegetables like strawberries, cucumbers,
and even broccoli are over 90% water, and can supplement liquid intake while
providing valuable nutrients and fiber. Drinking well might also have various
long-term benefits. Studies have shown that optimal hydration can lower the
chance of stroke, 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.
1. How much water do humans compose? How much to babies compose?
2. Detail the role of water play in our bodies. For what reason why we still
need to drink water?
3. Enumerate the long term benefits of water intake.