Yes, You Can Replace Regular Water With Seltzer Water

Photographed by Anna Jay.
In the summer, when it's hot and every crevice of your body is sweating, there's nothing quite like cracking open a can of La Croix — and then another, and another, and another. Maybe it's the feeling of the cold frosty can on your fingertips, or the sensation of the bubbles going down your throat, or the sweet satisfaction of finishing off a can, but often seltzer and sparkling water just seems more hydrating or exciting than regular flat water.
Given the choice between drinking seltzer and plain water, many people would opt for the bubbly, due to taste alone. But when you're parched and on the verge of dehydrated, it can feel like a dilemma. While both beverages are technically water, is sparkling water equally as hydrating as flat water, or is that all in your head?
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First, it's important to understand what seltzer even is. Seltzer is water and carbon dioxide gas (hence the term "carbonated") that has an effervescent quality. Sometimes seltzer contains added ingredients such as sugar or sodium, which give it flavor or taste, and other times it's just straight-up water. Compared to other flavored carbonated drinks — looking at you, soda and beer — seltzer water is certainly a healthier option, because it contains very little sugar and often none at all.
When it comes to hydration, the short answer is that seltzer water and flat water are equal, explains Ron Maughan, PhD, professor in the school of medicine at St. Andrews University. A 2016 study authored by Dr. Maughan found that sparkling water and regular water fall at the same point on a "beverage hydration index," meaning the hydration effects will be exactly the same if the same volume of each liquid is consumed. However, there are some other factors that may affect seltzer's hydration potential beyond just the beverage contents, he adds.
Some people just prefer drinking seltzer over water, which may help keep them hydrated, too, Dr. Maughan says. "If they like what they're drinking and drink more, that will clearly affect the response," he says. Anyone who's reached for a can of La Croix over a glass of tap water understands what he's talking about here. What matters most is that you're drinking some liquid, and if it happens to be bubbly, then that's still great.
Luckily for those of us who are obsessed with seltzer, there's no real harm in indulging this summer. "There is very little gas in sparkling water," Dr. Maughan says. "Most is dissipated when the bottle is opened, as it sits in the glass, or in the mouth as it is being consumed." In other words, your body can't really tell the difference between seltzer and water. "By the time it is emptied from the stomach, and reaches the small intestine where it is absorbed, there is little difference between the two," he adds.
While we give you permission to go full seltzer this summer, it might not be the most appropriate drink all the time. For example, if you're exercising or are dehydrated from drinking alcohol, then you might want to opt for plain H2O or something with electrolytes that will replenish the fluids you've lost. But if you really can't stand drinking water, the good news is there are plenty of ways to stay hydrated that are more interesting than water sans sparkle.
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