Water

Water is an essential nutrient, just like the nutrients in food. Your body is made up primarily of water, which accounts for 50 to 80 percent of your body weight. Your requirement for water varies, depending on such factors as the temperature and humidity or your activity level. Water loss through perspiration during physical exertion can increase your body's need for water dramatically. Having diarrhea also can cause excess water loss from your intestines, so it's important to drink plenty of fluids when you have a bout of diarrhea.

In general, thirst is the best indicator that you need water. Don't quench your thirst with caffeinated soda or alcoholic beverages because caffeine and alcohol will only dehydrate you further. Older people may find that their thirst sensation has become dulled. If you are an older man, remember to drink at least eight glasses of water and other fluids, 8 ounces each, every day, regardless of whether you are thirsty, and especially in hot weather. It's easy to become dangerously dehydrated without realizing it when the weather is hot and humid.

The federal government sets standards for the safety and purity of drinking water, and most municipalities meet these guidelines. Occasionally, however, contaminants enter public drinking water supplies. If you are told that your local water facility is having problems with high bacteria counts or other contamination, boil your tap water before you drink it or use it for cooking. The plumbing in older homes sometimes leeches lead into tap water. If you suspect that your plumbing might have lead-containing solder, run your tap water for several minutes every morning before drinking it. Always use cold water when cooking because hot water can cause lead to leech from pipes even faster.

Fluoride is an element that occurs naturally in the water found in some parts of the United States. In other regions, local municipalities add fluoride to public water supplies to help prevent tooth decay. Fluoridation of water is safe and is largely responsible for a substantial nationwide decrease in tooth decay.