Definition People can live for weeks without food. Without water, people will die within days. The human body is 50% to 70% water.
How does the nutrient affect the body? Water is one of the most important parts of the diet. Body fluids are mostly water. These fluids flow through arteries, veins and capillaries and carry nutrients and wastes. Fluids fill cells and the spaces between them to keep tissues healthy.
Water is also needed for many chemical reactions in the body. Water dissolves vitamins, minerals and other nutrients. Water helps keep joints lubricated. Water helps regulate body temperature. When hot water, in the form of perspiration, evaporates from the skin it cools the body. This keeps the body's internal temperature within a very small range.
Information Adults need at least two litres, or eight cups, of water every day for good health. Children need four to eight cups depending on age and size. The easiest way to get water into the body is to drink it. Other fluids, and even some foods, have water. These can help meet daily water needs. Milk, fruit juice and even carbonated fizzy beverages are good sources of water. Drinks with caffeine do not help meet daily water needs. Caffeine is a diuretic and causes the body to lose water. Alcohol does not count toward meeting daily water goals. Choose water or low-joule drinks if you need to loose weight.
One of the most important jobs of water is to maintain the body's fluid balance. This is a delicate balance of minerals. These minerals, called electrolytes, dissolve in water. Electrolytes include sodium, potassium and chloride. Electrolytes determine how much fluid stays in cells and how much remains outside cells. An imbalance is not healthy. Too much water inside cells is called "oedema" or simply "fluid retention." Too much water outside cells is called "dehydration."
Many medical conditions and drugs affect fluid balance. The kidneys do most of the work of controlling fluid balance. People with kidney disease often have special needs in terms of the amount they must drink.
A poor water intake dampens your concentration, and may show as headaches, cramps, confusion, irritability and a strong smelling darkening coloured urine.
Water helps to prevent constipation, regulate body temperature and reduce kidney stones, or risk of kidney disease. Thirst is a sign that your body is too low on water. Drink water to prevent thirst rather than waiting for it to appear.
Author: Clare Armstrong, MS, RD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 13/11/2004 Contributors Potential conflict of interest information for reviewers available on request
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