In 1945, the Food and Nutrition Board of USA published a recommendation that people need 10 cups of water a day. This quickly becomes the mantra of every doctor and nutritionist.
What they all have missed is that the recommendation continues with “most of this quantity is contained in the food we eat.”
“Water is present in the fruits and vegetables. It is present in the juices, and beer, and even tea and coffee. Before anyone tells you that the coffee will dehydrate you, know that studies have shown that this is also not true.
Although I recommend water as the best drink for consumption, it is certainly not the only source of hydration. You do not take all the water you consume through drinks only. Also you don’t even need to worry that you are never thirsty. The human body is finely tuned to give a signal long before it becomes dehydrated,” explains Aaron E. Carroll, who in 2007, in the British Medical Journal reported that the rule of 10 cups of water is a lie.
He says that there is no evidence that healthy people have any benefit from the additional quantities of water. Also, there is no evidence that drinking more water keeps your skin hydrated, or that helps you look healthier, or that prevents occurrence of wrinkles.
Carroll confirms what he has said before, after the media’s attention was attracted this summer by a recent study that showed that many children face dehydration because they do not drink enough water. In his disclaimer of the research he notes that as a crucial evidence of dehydration a concentration of urine is used.
In this study a critical limit is considered to be 800 mOsm/kg, a figure that, based on surveys and conversations with colleagues, he believes is no relevant.
“It is possible that some children need better hydration. But at some point, we risk that a healthy and normal condition could be declared as a sickness. When laboratory values of two-thirds of healthy children, year after year, are marked as ‘abnormal’ it may be that the definition is the problem, and not their health.
There is no formal recommendation for the daily quantity of water needed by humans. This quantity depends on what people eat, where they live, how big they are and what they do. But people in the modern society live longer than ever, and have freer access to drinks than ever in human history, it is not true that we are dehydrated,” explains Dr. Carroll, Professor of Pediatrics at the Indiana University.