It's free. It has no calories. It's all-natural.

It's water.

Water is that clear liquid you probably use to wash dishes, clothes, cars and yourself. Some people believe it's one of the best-kept health secrets of our time.

Our bodies use water to bring oxygen and nutrients to the cells, to remove waste, to bathe our brains and to lubricate our skin and joints. By weight, men are about 55 percent water, women about 45 percent. And yet many of us may be going through life dehydrated, our water gauges reading "low."

Had a headache lately? Could be a lot of things, including stress. Or it could be you're dehydrated.

Feeling tired? Lethargic? Drink two glasses of water and see what happens.

Running out of steam early when you're working out? Had a kidney stone or a kidney infection? Constipated? Having trouble controlling your appetite? Feel lightheaded?

That's right, water - or, to be precise, a lack of it - can be a factor in all of the above.

Dehydration, a cause for concern

It can be more serious, especially for the very old and the very young. It's "very common" for elderly people to be admitted showing serious effects from dehydration, said Dr. Raymond J. Malta, an osteopath based at South Jersey Hospital.

"They come in all the time," he said. "When they are dehydrated they're not thinking right ... completely irrational behavior. That's part of the syndrome."

In some of those cases, he said, dehydration results in coma or death.

Quagliani, also a spokesperson for the Chicago-based American Dietetic Association, finds it ironic that people spend so much on vitamins, ginseng, health clubs, herbal teas and other expensive health enhancers when water is free and could well make more of a difference in our daily lives.

"I generally don't think people drink enough," Quagliani said. She keeps a 1.5-liter bottle at her desk, "and I try to drink two of those a day ... and other people are stunned. It's like a foreign thing to them to even think about purposely drinking water. But I've always recommended that people drink proactively."

She said the average person loses about 10 to 12 cups of water a day, so we've got to drink that much just to keep up. But if you add hot weather or a workout or if you start the day dehydrated because of a few beers the night before, by the time your thirst signals a problem you're going to have a hard time catching up. One estimate put the amount of water burned daily, if you add hard work, sports and normal temperatures, at 33 glasses, or 1.7 gallons.

Caffinated coffee and alcohol actually hurt because they're diuretics.

"It's not unusual for anyone to be perhaps 1 or 2 percent dehydrated at any given time," said Lawrence J. Armstrong, an exercise physiologist based at the University of Connecticut.

And how would that affect us?

Suppose you work on the yard for a couple hours, or you go for a walk on a hot day. Either way you might lose an additional 1 percent of your body weight through sweating. That's only 1.5 pounds for a 1 50-pound person. "Which is not difficult to do, " Armstrong said, "and you could put yourself in a position where your physiological functions would be compromised."

That might mean a throbbing headache, weakness or an inability to continue. Armstrong, who has trained world-class marathoner Alberto Salazar, believes that's why dehydration isn't just an issue for athletes.

Check color of urine

Want to know if your water tank is full? Look at your urine. If it's dark, you may be dehydrated. (Vitamins, among other substances, can darken urine.)

If your urine is almost clear, you're in good shape. Quantity is also a good sign.

"Trips to the bathroom are an indication that you're doing something good, that you're properly hydrated," Quagliani said.

"This is absolutely an issue for normal, everyday people," she said. "Having enough water and being hydrated is going to make all the functions in your body go better. We're so lucky in this country. Water is cheap and plentiful."

Maybe that's the problem. Maybe if somebody charged $7 a bottle and advertised it as an all-natural calorie-free energy drink, Americans would fall in love with it.

Medical benefits? Don't take our word for it. Ask a urologist.

"If your urine is yellow or the color of cider, you're at risk of kidney stones," said Rob Goldlust, a urologist based in Woodbury. Goldlust said half the urine samples he sees are yellow, indicating dehydration.

"If you ever have a kidney stone, the next time I see you, you'll probably be walking around with a jug of water," he said.

Water's role in diet

Been trying to work more fiber into your diet?

"You have to drink more fluids for it to work," said Betsy German, a registered dietitian at Burdette Tomlin Memorial Hospital in Cape May Court House. "Otherwise it will have the opposite effect."

German said she has noticed that people who favor sugared drinks over water tend to be overweight, and she doesn't think that's a coincidence.

"When you're thirsty your body is asking for water, not sugar," she said. "I recommend water all the time, but people in this country always seem to want something that's sweet. I guess it's a habit."

But even German doesn't always keep up. At work, there are times she realizes she's thirsty, "But sometimes I figure I can wait, and by the time I do get a drink, I'm starting to feel a little tired and a little lightheaded. "

"It's a simple t hing that often gets overlooked," she added.

Malta, the South Jersey Hospital physician, doesn't believe dehydration is epidemic.

"The average dude, walking around - not a problem," he said. The people who mostly have problems, he believes, are the ones who can't get to water - on the job, for example - or who deny themselves water because they want to reduce their trips to the bathroom.

Could dehydration explain much of our fatigue? Tough call, Malta said. But he knows from his own experience that when he's exercising, "If I don't have fluid on board, I feel pretty drained."

Could you make a kind of indirect leap from the marathon runner to the average guy (needing fluid to keep energy levels high)?

"Probably," he said.

Hot, humid weather calls for increased in take of water

Drinking enough water is important all year, but it's critical in hot, humid weather.

It's particularly important for older people to drink plenty of water, even when they're not thirsty, so they can stay ahead of the game.

Medical factors that may contribute to dehydration and heat-related illnesses (anything from cramps to lethargy to dizziness and heatstroke) include fever, infection, lack of recent heat exposure (the body can acclimatize itself), recent alcohol abuse, sunburn and lack of sleep.

Heat stroke warning signs include dry lips and tongue, headache, dizziness, an increase in heart rate and breathing, pallo r and weakness, then possibly confusion or euphoria and loss of consciousness. Sometimes people become combative. Sometimes they hallucinate, or they may quietly slip into a coma. There may be mild nausea, confusion, sleepiness or profuse sweating.

Keep in mind that fans aren't effective in cooling the body unless the air is cooler than the body temperature.

Even when the temperature is moderate, we lose water through perspiration, respiration and urination, and that's without excessive activity. We can also lose large amounts of water through vomiting or diarrhea.

Tips

- When it's humid, it's even more difficult for the body to cool off because sweat isn't evaporated as quickly, or at all.

- Many fruits and vegetables are good sources of water.

- Pregnancy or breastfeeding increases the need for water.

- Athletes, take note: The American College of Sports Medicine says: "Inadequate water may lead to premature exhaustion."

For more information

Sources for these articles include local physicians and dietitians, the American Medical Association's Council on Scientific Affairs, the AMA's Encyclopedia of Medicine, the American Dietetic Association and the American College of Sports Medicine.

For more information: - The American Dietetic Association's nutrition hot line, (800) 366-1655, has prerecorded nutrition messages and a referral service. The Web site - www.eatright.org might also be helpful.

- American College of Sports Medicine, P.O. Box 1440, Indianapolis, Ind., 46206-1440. Telephone: (317) 637-9200. FAX: (317) 634-7817. For a free copy of its paper, "Exercise and Fluid Replacement," send a self-addressed, stamped, business-size envelope to Fluids, ACSM Public Information Dept., P.O. Box 1440, Indianapolis, Ind. 46206-1440.

The Press of Atlantic City Copyright (c) 1997, The South Jersey Publishing Company.