MALMÖ – “Everyone knows” that you should drink eight glasses of water a day. After all, this is the advice of a multitude of health writers, not to mention authorities like Britain’s National Health Service. Healthy living now means carrying water bottles with us, sipping at all times, trying to drink our daily quota to ensure that we stay hydrated and healthy.
Indeed, often we drink without being thirsty, but that is how it should be: as the beverage maker Gatorade reminds us, “your brain may know a lot, but it doesn’t know when your body is thirsty.” Sure, drinking this much does not feel comfortable, but Powerade offers this sage counsel: “you may be able to train your gut to tolerate more fluid if you build your fluid intake gradually.”
Now the British Medical Journal reports that these claims are “not only nonsense, but thoroughly debunked nonsense.” This has been common knowledge in the medical profession at least since 2002, when Heinz Valtin, a professor of physiology and neurobiology at Dartmouth Medical School, published the first critical review of the evidence for drinking lots of water. He concluded that “not only is there no scientific evidence that we need to drink that much, but the recommendation could be harmful, both in precipitating potentially dangerous hyponatremia and exposure to pollutants and also in making many people feel guilty for not drinking enough.”
So why do we keep hearing (and believing) that more water is better? Well, obviously Gatorade and Powerade would like us to drink more of their products, and getting us to gulp more than we would naturally like seems like a brilliant marketing move. Likewise, the latest Hydration for Health science gathering, which promotes drinking more water, has been sponsored by Danone, which sells bottled water under brand names like Volvic and Evian.