In the not particularly distant past, I worked at a start-up online publication. I didn't enjoy the job and didn't last too long, but you know what I did like? The liter bottles of free seltzer. I drank them constantly. Missed breakfast? Sip a raspberry-lime one. Annoyed because I had to write another post about ad tech and clickthrough rates? Thirty-two ounces of the bubbly stuff should ease the pain. (This is only partially true. If someone asks you if you'd like to cover ad tech, the answer is always "no.") Winded from a particularly intense mid-afternoon ping-pong game? Straight-up plain seltzer should be good.
Because I'm a moron, I was also training for a marathon during this short period of my life. While I figured that I would be properly hydrated since, along with two or three cups of coffee per day, I was constantly drinking water, I often felt like I wasn't. I would start a long training run with a dry mouth and fatigued limbs. Occasionally, I would wonder if the carbonation had something to do with my struggles. Was seltzer water not as hydrating as regular water? But these thoughts usually arrived around mile eight, at which point I was hoping to simply finish the run, not dissect my physiological condition. Eventually, I moved on from the job, the marathon, and my bubbly water-related concerns.
I have been freelancing for the past two years, so seltzer wasn't in the budget, but I recently purchased a Soda Stream, which magically inserts carbonation into regular tap water. (Note: not actually magic, but still totally awesome.) As a result, I've been drinking far more artificially-carbonated water again. It made me reconsider the hydration question. On one hand, it's just water—something the Soda Stream makes dramatically clear—right? On the other, I feel better, anecdotally at least, when I only drink tap water. So what gives?
Well, you can't fight science. Perhaps my own personal hydration theories were entirely psychosomatic.
TO FIND OUT, I did what any journalist in 2013 does: asked the Internet. That, not surprisingly, was more or less useless. A Self.com quiz suggested mineral water, sparkling water, and seltzer were all equally hydrating, although bubbles might cause minor stomach irritations. Someone called the Nutrition Diva gave roughly the same answer, although her post seemed to indicate that she had simply culled information from the Internet as well. It was all very inconclusive.
Determined to find the truth, I turned to the experts. Dr. Susan Yeargin is an assistant professor in the Athletic Training Education Program at the University of South Carolina. She also happens to be a noted hydration expert, and I emailed her asking for her thoughts. "I have honestly not come across any research that indicates that seltzer water is inferior to regular water in hydrating individuals," she wrote, responding a few hours later and promising to ask some of her colleagues and get back to me. I went to the kitchen and made myself some seltzer.
Yeargin eventually came through. She sent me PDFs of two articles. One, from a 1991 issue of International Journal of Sport Nutrition, was called "Consumption of Carbonated and Non-Carbonated Sports Drinks During Prolonged Treadmill Exercise in the Heat.” The other, "Drinking Behavior and Exercise-Thermal Stress: Role of Drink Carbonation," ran in a 1994 issue of the same publication. According to Yeargin, they reached the same general conclusion: "Long story short ... there is no difference between carbonated and non-carbonated beverages in hydrating someone. They both have the same physiological responses."
Well, you can't fight science. Perhaps my own personal hydration theories were entirely psychosomatic. I used the Soda Stream again and moved on with my life, chagrined but encouraged that I could drink as much seltzer as I wanted.
The next morning, however, there was another email in my inbox from Yeargin. Her colleague in hydration, Dr. Stavros A. Kavouras—who works in the Human Performance Laboratory at the University of Arkansas—passed along two articles. "Effects of Carbonated and Non-Carbonated Beverages at Specific Intervals During Treadmill Running in the Heat" ran in the International Journal of Sport Nutrition in 1993, while "The Effects of Beverage Carbonation on Sensory Responses and Voluntary Fluid Intake Following Exercise" was featured in 1997. The research didn't say anything about a lack of hydration resulting from seltzer, but according Yeargin, it did indicate "that carbonation might decrease how much a person voluntarily drinks."
Perhaps I felt dehydrated because I was actually drinking less. That's a theory I could buy, as it is, after all, how hydration works. One thing is definitely certain: I should drink less coffee.