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Into the drink

Dear Lucy: A friend told me that sparkling water (seltzer) doesn’t count towards the eight glasses of water we are supposed to drink each day. But I disagreed. It seems to me that water is water. Who is right? —Tiny Bubbles

Illustration of a spinning prize wheel

Dear Bubbles: Lucy recruited MIT Medical nutritionist Anna Jasonides to be the arbiter in this disagreement, and she came down firmly on your side. “Water is water,” Jasonides agrees, “and other fluids, like juice and milk, will also keep one adequately hydrated.” She notes that caffeinated drinks can contribute to one’s daily fluid intake as well. “Studies show that the average person retains between half and two-thirds of the fluid consumed by drinking caffeinated beverages,” she notes, “while individuals who regularly consume these kinds of drinks retain even more.”
And don’t just take her word for it; the Food and Nutrition Board of the National Academies of Sciences concurs, writing that all sources can contribute to total water needs—“beverages (including tea, coffee, juices, sodas, and drinking water) and moisture found in foods.” In fact, they note, moisture in food accounts for about 20 percent of total water intake. 
And that eight-glasses-of-water rule? “Not as scientific as we might like to think,” according to Jasonides, not to mention that excessive liquid intake can wreak havoc with one’s daily schedule. “Many of my patients feel bad that they don’t drink eight glasses a day,” Jasonides reports. “But the ones who do drink eight or more complain of peeing too much!
“I tell the first group of patients not to worry,” she continues. “And I tell the drinkers, ‘If peeing is interfering with your day, and you can’t make class because you have to go, you’re drinking too much!’”
Not surprisingly, the Food and Nutrition Board agrees again, concluding that for healthy individuals, “thirst and consumption of beverages at meals are adequate to maintain hydration.” Or, as Lucy might put it, “If you’re thirsty, drink something! And if you’re not thirsty, don’t!”
Lucy hopes you now feel free to drink all the sparkling water you’d like, when you like. And if you are thirsty, drink some more! —Lucy

Back to Ask Lucy Information contained in Ask Lucy is intended solely for general educational purposes and is not intended as professional medical advice related to individual situations. Always obtain the advice of a qualified healthcare professional if you need medical diagnosis, advice, or treatment. Never disregard medical advice you have received, nor delay getting such advice, because of something you read in this column.