For decades, we have been advised to drink at least eight glasses of water per day, which is why physician Heinz Valtin made headlines all over the world with a study that could find no proven medical rationale for this advice. Should you stick to it anyway? Two top researchers in the field weigh in.
F. Batmanghelidj, M.D., author of Your Body’s Many Cries for Water “There’s been a paradigm shift about the role of water in the body, and Dr. Valtin’s views represent the ancient thinking. He believes water is a neutral means of transport, and that all physiological functions of the body belong to the solid matter. The new thinking is that water is a nutrient, an active material crucial to the healthy function of the brain and cells.
When you’re dehydrated, the body goes into what I call “drought management mode,” which is ultimately the cause of many major diseases. Breathing is affected, which is why kids who are dehydrated develop asthma. Dehydration affects the heart muscle and eventually causes cholesterol buildup in the arteries. And since water is the main source of energy for brain function, cognitive abilities can suffer as well.
Thirst is the body’s response to the fact that it’s dehydrated, so by the time you recognize that you are thirsty, a lot of the damage has already occurred. We also know that people lose their perception of thirst as they age. One study shows that 50- and 60-year-olds who had been deprived of water for 24 hours still didn’t feel thirsty.
I think eight glasses of water a day, plus some salt, is the absolute minimum you need to stay healthy. And it’s got to be water; other liquids can actually dehydrate you. Also, ideally, urine should be colorless.
Heinz Valtin, M.D.,
author of two widely used textbooks on water balance and the kidneys
“I don’t object to drinking water. But I haven’t found a single study in a peer-reviewed journal to support the idea that everyone must drink at least eight glasses a day.
Drinking very large amounts of fluid is necessary under certain conditions: in hot climates; if you’re exercising strenuously; or if you have diabetes insipidus (different from diabetes mellitus or sugar diabetes) or kidney stones. And I know that some studies show that drinking at least five glasses a day cuts the risk of fatal heart disease. But I still think the link needs to be more conclusively established.
In some cases, drinking lots of water can even be harmful. “Water intoxication” is a sometimes-fatal malfunction of the body in which the kidneys can’t excrete water as quickly as the sufferer is drinking it. Such cases have been suffered by athletes running marathons and teenagers taking the drug Ecstasy.
The body’s system of balancing fluids is very sensitive, quick, and accurate. If you are healthy and your body needs more water, you get thirsty and drink the amount you need to bring your body back into balance. Follow your thirst and you’ll be okay.
Generally, that amounts to six to seven glasses of fluids a day as long as your urine is moderately yellow in color. And research has shown that coffee, tea, juices, and even, in moderation, soda and beer, are also okay.”
Follow your own instincts, stay hydrated- especially when working outdoors or participating in physical activities.