The history of science is littered with surprising discoveries that forever changed our conception of the unvierse and ourselves. The earth is a sphere, even though it appears flat. Life has no designer, even though it looks designed. But this may be the most surprising discovery yet, a fact that seems to undermine one of the basic truisms of my morning routine:
It was long thought that caffeinated beverages were diuretics, but studies reviewed last year found that people who consumed drinks with up to 550 milligrams of caffeine produced no more urine than when drinking fluids free of caffeine. Above 575 milligrams, the drug was a diuretic.
So even a Starbucks grande, with 330 milligrams of caffeine, will not send you to a bathroom any sooner than if you drank 16 ounces of pure water. Drinks containing usual doses of caffeine are hydrating and, like water, contribute to the body’s daily water needs.
Can that be? The last time I drank a large Starbucks coffee I had the misfortune of sitting in a window seat on a transcontinental flight. Let’s just say that I was yearning for a catheter. The real question, of course, is this: If coffee isn’t a potent diuretic, then why does it seem like one?