If
the importance of a nutrient is judged by how long we
can do without it, water ranks as the most important.
A person can survive only eight to ten days without
water, whereas it takes weeks or even months to die
from a lack of food. Water circulates through our blood
and lymphatic system, transporting oxygen and nutrients
to cells and removing wastes through urine and sweat.
Water also maintains the natural balance between dissolved
salts and water inside and outside of cells. |
How
much water a person needs depends largely on the volume
of urine and sweat lost daily, and water needs are increased
if a person suffers from diarrhea or vomiting or undergoes
heavy physical exercise.Water is replenished by drinking
liquids, preferably those without caffeine or alcohol,
both of which increase the output of urine and thus
dehydrate the body. Many foods are also a good source
of water—fruits and vegetables, for instance,
are 80 to 95 percent water; meats are made up of 50
percent water; and grains, such as oats and rice, can
have as much as 35 percent water. |
