Doctor, how much water should I drink? I hear this question every day. We all know that enough water is essential for good health, yet everyone's needs are different. It's a simple question, with a not so simple answer!Water makes up about 60% of our body weight and is the principal chemical component in the body. Every system depends on it. Water flushes toxins out of vital organs; carries nutrients to the cells; and moisturizes the nose, ears, throat, blood vessels, and tissues. Minor dehydration will result in thirst, loss of appetite, dry skin, skin flushing, dark colored urine, dry mouth, fatigue, weakness, chills and head rushes. More dehydration leads to increased heart rate, increased respiration, decreased sweating, decreased urination, increased body temperature, extreme fatigue, muscle cramps, headache, nausea, and tingling in the limbs. Once dehydration reaches 10%below normal levels, fluid loss becomes an emergency and can be fatal. Signs include muscle spasms, vomiting, racing pulse, visual changes, painful urination, confusion, difficulty breathing, seizures, and unconsciousness. We lose water through breathing, perspiration, urine and bowel movements. Clearly, there is some ideal amount of water needed to replace these fluids and keep the system running correctly. The simplest approach is known as the eight by eight rule. Drink eight glasses of eight ounces of water per day. This is based on the replacement method: an adult urinates about six ounces of water per day, and we lose roughly an additional four cups each day through breathing, sweating, and bowel movements. Food accounts for roughly 20% of our total fluid intake, so if we consume about eight cups of water or other beverages a day along with a normal diet, we will typically replace the fluid lost. This is pretty general, but will normally suffice. Another method is to look at the toilet bowl! If you drink enough fluid so that you rarely feel thirsty and produce about six cups or more of colorless or slightly yellow urine a day, your fluid intake is probably adequate. Since we don't typically measure our urine output, simply check the color. Now that we have a general rule of thumb, let's explore factors that may change our specific requirement. Regular exercise, whether or not we sweat, demands that we drink extra water to compensate for the fluid loss. In general, drinking 1 1/2 to 2 1/2 extra cups of water should suffice for short bouts of exercise, but intense exercise lasting more than an hour requires more, and if you tend to sweat heavily, even more fluid replacement is required. Sport drinks are more useful than water after heavy exercise. The environment affects fluid requirements. Hot or humid weather will increase sweating. Spending time in heated buildings causes the skin to lose moisture. High altitudes (over 8,200 feet) may trigger increased urination and more rapid breathing, using up more fluids. Women who are pregnant or nursing require more hydration. Pregnant women are advised to drink about 10 cups daily and women who are nursing need about 13. Illness and various health conditions change the formula for fluid replacement substantially. Fevers, vomiting, diarrhea, bladder infections and kidney stones are examples of conditions that require us to drink more. On the opposite end of the spectrum are congestive heart failure, liver failure, and kidney failure, where fluid restriction is often necessary. Remember that milk, juice, soup, and fruits and vegetables all contain some of the water that we need. Alcohol and caffeinated beverages (some sodas, coffee, tea, etc.) act as diuretics, however, and cause some fluid loss as well. Is it dangerous to drink too much water? There is actually a condition known as water intoxication, which can be caused by a psychological condition known as psychogenic polydipsia. When too much water enters the body's cells, the tissues swell with the excess fluid. The result is a potentially dangerous decrease in sodium concentration. Here are some simple guidelines to help avoid dehydration: • Drink a glass of water with each meal and between meals • Hydrate before, during and after exercise • Try substituting sparkling water or other beverages for alcoholic drinks or sodas • Work with your physician to determine the proper amount of fluid consumption for your specific needs. I wish you the best of health. Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 8301 E. Florence Ave., Suite 100, Downey, CA 90240.

********** Published: December 9, 2010 - Volume 9 - Issue 34