July health news: Myths about how much water you should drink

Water, water, everywhere -- sitting on your desk at work, toted along while you window shop, waiting in a gym locker for post-workout guzzling. We've been told repeatedly to drink water all day long as though it's a magic bullet for whatever ails us. But according to two kidney researchers, there's no proof that lots of water is good for your health. 

Dr. Stanley Goldfarb and Dr. Dan Negoianu of the University of Pennsylvania in Philadelphia reviewed reports on drinking increased amounts of water throughout the day and found that not only does more water not equal better health, in certain cases it can make you quite ill.

"There's nothing wrong with drinking water as long as one doesn't do it to excess; there's also nothing right about it," says Goldfarb. "People who bother to carry around water bottles and force themselves to drink water all day long are really doing absolutely nothing that benefits them."

Busting the water myths
The review, published in the Journal of the American Society of Nephrology in April 2008, debunks four myths about water and health:

Myth 1: Water improves skin tone. There has never been a study that compared two sets of people -- one who drinks water, one who doesn't -- and their skin tone, meaning there's no reason to believe water can change the way you look. Furthermore, says Goldfarb, there's so much water in your body -- a 200-pound person has 120 pounds of water -- that drinking a glass of water, which weighs about half a pound, would have no effect.

"A glass of water is going to distribute itself throughout every cell in your body -- that's not going to change the skin on your face. The amount that's going to get to your face is, at most, 10 to 15 CCs; a thimble full." Only in extreme cases -- such as crossing the Mexican desert -- will someone become dehydrated enough for skin tone to change.

Myth 2: Water relieves headaches. One pivotal study that looked into the influence of water on migraine headaches actually found no evidence that water could help alleviate or ward off the pain.

Myth 3: Water flushes toxins from the body. One of the kidneys' important functions is to filter blood and excrete toxins, but drinking a lot of water doesn't increase this filtration function. "All you do is excrete the same amount of toxins in a larger volume of urine," explains Goldfarb.

Myth 4: Water reduces appetite. There is some evidence that if you drink a lot of water right before eating, you'll feel fuller and your caloric intake during the meal will be reduced. "But, since water is cleared from the gastrointestinal tract very quickly, it's likely that people who try to diet by not changing their food consumption and just drinking water, will be hungry between meals," says Goldfarb. Furthermore, there has yet to be a study that compares two groups of people and weight loss through water consumption.

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