MedlinePlus Medical Encyclopedia: Water in diet

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Water in diet

Contents of this page:
Alternative Names Definition Function	Food Sources Side Effects Recommendations

Alternative Names

Diet - water; H2O

Definition Return to top

Water is a combination of hydrogen and oxygen. It is the basis for the fluids of the body.

Function Return to top

Water makes up more than two-thirds of the weight of the human body. Without water, humans would die in a few days. All the cells and organs need water to function.

Water serves as a lubricant and is the basis of saliva and the fluids surrounding the joints. Water regulates the body temperature through perspiration. It also helps prevent and alleviate constipation by moving food through the intestinal tract.

Food Sources Return to top

Some of the water in our body is obtained through foods we eat and some is the byproduct of metabolism. But drinking water is our main, and best, source of water.

We also obtain water through liquid foods and beverages, such as soup, milk, and juices. Alcoholic beverages and beverages containing caffeine (such as coffee, tea, and colas) are not the best choices because they have a diuretic (water-excreting) effect.

Side Effects Return to top

If adequate water is not consumed on a daily basis the body fluids will be out of balance, causing dehydration. When dehydration is severe, it can be life-threatening.

Recommendations Return to top

Six to eight 8-ounce glasses of water are generally recommended on a daily basis.

Update Date: 8/8/2007

Updated by: Cynthia Dennison Haines, MD, family physician specializing in nutrition, fitness, and preventive health, St. John's Mercy Medical Center, St. Louis, MO, and Assistant Clinical Professor, St. Louis University's School of Medicine, Department of Community and Family Medicine.

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