Not only nonsense, but thoroughly debunked nonsense

From Like Water for Climate by Bjørn Lomborg.

“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.”

Echoes many of the themes in Samuel Arbesman's The Half-Life of Facts which chronicles many instances of things that everybody knows that just aren't so. It also calls to mind the quotation attributed to Mark Twain, “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.”

This is one of those minor life mysteries which I suspect all of us carry around with us but never quite get around to resolving. In this instance and in my case, I have for a number of years wondered about this insistent advice to drink plenty of liquids. On a boy scout hike, sure. During sports, absolutely. But just walking around? I grew up in the tropics and in deserts and we never made a point of drinking eight glasses a day. You drank when you were thirsty and carried water with you only when you were going someplace where you knew there wouldn't be water. From my office window I see a dozen people a day strolling around the neighborhood clutching bottles of water.

Each time I think, "Why?" But life's too short and I haven't been that curious so I never had an answer. But if you wait long enough, sooner or later an answer sometimes comes your way, even about some of the less consequential questions.