A Purdue University graduate student spent part of last month handing seltzer drinkers a small piece of good news. In a study of 20 adults presented on July 26 at NUTRITION 2026, unsweetened sparkling water lowered the acidity in the mouth only briefly and never reached the point at which tooth enamel begins to dissolve. Sugar-sweetened soda did considerably worse.
Then there is the part that got lost in the coverage. The two sparkling waters in that experiment were plain and calcium-fortified. No lime. No grapefruit. No black cherry. The flavored seltzers stacked in American refrigerator doors contain the one ingredient dentists have been flagging for two decades, and none of them were in the study.
Twenty Mouths, Four Drinks, and a Stopwatch
Wajiha Zulfiqar, a graduate student in nutrition science at Purdue, working with researcher Cordelia A. Running, gave the same 20 adults four beverages: sugar-sweetened soda, regular unsweetened sparkling water, calcium-fortified sparkling water, and plain water. Using the same participants across all four drinks limits person-to-person variation that muddies smaller beverage studies. Saliva pH was measured before drinking and at several points afterward.
Enamel starts to demineralize when oral pH drops below roughly 5.5. According to the American Society for Nutrition, soda produced a salivary pH significantly lower than water at both 2 and 20 minutes. Plain sparkling water caused a temporary dip at 2 minutes. The calcium-fortified version dipped at 5 minutes. Both returned near baseline by 20 minutes, and in every case, saliva restored the mouth to a level above the erosion threshold.
Zulfiqar said unsweetened sparkling water "may be a lower-risk alternative to soda" when consumed in moderation alongside good oral hygiene. The work was presented as a poster abstract. ASN notes that abstracts at its meeting are selected by an expert committee but generally do not undergo the peer review required for journal publication, which makes these results preliminary rather than settled.
The Ingredient That Was Never in Those Cans
Carbonation creates carbonic acid, a weak acid that gives seltzer its bite. Flavored sparkling waters commonly add citric acid or other flavor acids, which are stronger and lower the pH. A survey of 379 commercially available American beverages published in the Journal of the American Dental Association reported that low pH is the primary determinant of a drink's erosive potential, and that citrate can chelate calcium from teeth even at higher pH values. Ninety-three percent of the tested drinks had a pH below 4.0.
That is the gap in the new research. The Purdue design tested the two gentlest members of the sparkling water family and left out the flavored products that dominate supermarket shelves. Whether a citrus seltzer behaves the same way inside a real mouth is a question this study was never built to answer.
What Soaking Real Teeth Showed That Saliva Cannot
In 2022, researchers publishing in JADA Foundational Science took a blunter approach. They soaked specimens cut from freshly extracted human premolars in seven sugar-free beverages plus one sugary soda for 24 hours, an exposure the team treated as approximating a year of ordinary drinking.
One detail matters and was widely lost in the coverage. The specimens were cervical dentin, the softer tissue beneath enamel, which erodes at a higher pH than enamel does. Five of the eight drinks produced significant erosion. Sugary and sugar-free sodas both did damage, and the sweetener mattered less than the acid. Flavored sparkling waters also produced measurable erosion, though less than either soda. The only beverages that caused none were still, unflavored bottled waters.
Edmond Hewlett, an American Dental Association spokesperson and professor at the UCLA School of Dentistry, said that the more acidic the drink, the greater the risk of erosion "with frequent consumption." The two studies are measuring different things. Purdue measured the fluid surrounding teeth. The ADA-published team measured tooth tissue in a dish.
Frequency, Not the Brand, Is What Decides This
Both lines of evidence point to the same practical variable, and it is not the label. It is how a drink is consumed. A seltzer finished in ten minutes gives saliva a clear window to buffer the acid. The same can sipped across a four-hour workday keeps the mouth acidic in repeated waves, which is the pattern dentists associate with erosion.
ADA guidance on dental erosion suggests avoiding dietary acids between meals, drinking through a straw positioned behind the front teeth, not swishing or holding acidic liquid in the mouth, rinsing with water rather than brushing immediately afterward, chewing sugar-free gum to keep saliva flowing, and drinking milk alongside acidic meals.
The limitations here are substantial and worth stating plainly. The Purdue study involved 20 adults, measured only short-term salivary pH after a single exposure, examined no teeth, tested no flavored products, and has not been peer-reviewed. Salivary pH is a proxy for erosion risk, not a measurement of mineral loss. The 2022 soaking work was conducted in a laboratory dish rather than a living mouth, where saliva, tongue movement, and fluoride all intervene. Neither design can tell an individual what a decade of seltzer will do to their molars.
The Purdue researchers say they now plan longer-term work examining how habitual sparkling water consumption affects the mouth environment over months and years. Until that arrives, the honest summary is narrow: swapping soda for plain seltzer looks like a downgrade in acid exposure, the flavored versions remain an open question, and anyone with tooth sensitivity, reflux, or dry mouth should raise it with a dentist rather than a comment section.
Key Questions Answered
What did the new study actually find?
In 20 adults, sugar-sweetened soda lowered salivary pH the most and for the longest. Plain and calcium-fortified sparkling waters caused brief dips that saliva corrected within about 20 minutes, keeping levels above the threshold linked to enamel damage.
Why does the flavored seltzer question matter?
Flavored versions commonly contain citric acid or similar flavor acids that lower pH more than carbonation alone. They were not tested in this study, so its reassurance does not automatically extend to them.
Is this research peer-reviewed?
No. It was presented as a conference abstract at NUTRITION 2026 and should be treated as preliminary until published in a peer-reviewed journal.
What pH level damages teeth?
Enamel demineralization generally begins below about 5.5. Dentin, the softer layer beneath, is more vulnerable. Damage also depends on how often and how long teeth are exposed.
Does a drinking habit change the risk?
Yes. Finishing a drink in one sitting gives saliva time to neutralize acid. Sipping continuously throughout the day extends acid exposure, which is the pattern most associated with erosion.
What is the safest thing to drink for your teeth?
In the soaking research, still, unflavored water was the only beverage that produced no erosion. Fluoridated tap water and milk are also commonly recommended by dentists.
Should anyone stop drinking sparkling water based on this?
No study here supports a blanket recommendation either way. People with existing tooth wear, sensitivity, reflux, or dry mouth should discuss their own risk with a qualified dental professional.
