Everyone from The Times to teen magazines to your own doctor have told you that one of the most important things you can do to keep healthy is to make sure you drink at least eight glasses of water a day. We lug around huge water bottles and do our best to force down the recommended eight glasses, often believing that drinking enough water will help us lose weight. The problem with all of this is that there’s no medical reason for the recommendation. Some might even call it eight glasses of B.S.
You’ve heard this myth everywhere, but who first recommended it? The earliest record was back in 1945, when the Food and Nutrition Board of the National Research Council (US) stated that adults should take in about 2.5 litres of water a day, most of this contained in prepared foods. If you ignore the last part of that statement, you would interpret this statement as a mandate to drink eight glasses of water per day (2.5 litres is just over 5 pints, which is close to eight glasses of water). However, even in 1945, the Research Council clearly stated that most of the water you need is already present in the foods you eat.
A few years later, a nutritionist named Dr Frederick Stare also seemingly endorsed drinking eight glasses of water a day, but he said that it could be in the form of coffee, tea, milk, soft drinks or even beer. Plus he also made the point that fruits and vegetables are good sources of water. Even these experts never claimed that you had to get hydrated with plain old water.
There’s nothing wrong with liking water, but there is no scientific proof stating that you need to drink anywhere near eight glasses a day. One doctor who has made this his research focus, Dr Heinz Valtin, searched through many electronic databases and also consulted with nutritionists and colleagues who specialize in water balance in the body. In all of his research, and in all of the research we conducted to double-check his work, no scientific evidence could be found to suggest that you need to drink eight glasses of water a day. In fact, scientific studies suggest that you already get enough liquid from what you’re drinking and eating on a daily basis. We are not all walking around in a state of dehydration. Extensive US Department of Agriculture surveys measuring how much food and drink more than 15,000 people in fifty states consumed in a period of over three years show that the average person in the U.S. took in 2,188 millilitres (or 4.6 pints) of water a day.
Actually, people should be careful not to drink too much water. As demonstrated by a recent and much-publicized death of a young woman who participated in a water-drinking contest hosted by her local radio station, drinking too much can result in water intoxication and even death. Too much water dilutes the normal level of sodium in the blood, causing a condition called hyponatremia, in which brain cells can swell and die. Although not a common problem, it occurs more easily in young infants, which is why paediatricians do not recommend giving babies water (especially when they have diarrhoea).