Debunking the sparkling water myth

Dr. Adam Koppelman, DMD — Midtown Manhattan · August 31, 2026

“But is LaCroix okay?” is, no exaggeration, in the top five questions I get asked in a given week. Ahead of “do you take my insurance?” Behind “is it going to hurt?” The dental internet has spent the better part of a decade telling everyone that their sparkling water habit is quietly dissolving their teeth, and meanwhile most of my patients have virtuously swapped Diet Coke for lime seltzer and are now vaguely worried they made the wrong trade.

Good news for the seltzer converts: you made the right trade. Some news for the flavored-seltzer die-hards: it is a little more complicated than that. Here is the short version — with enough of the real science underneath that you can actually use it.

The one number your teeth actually care about

Enamel — the glassy outer shell of your teeth — is the hardest tissue in the human body, and also, unfortunately, non-living: no blood supply, no repair crew, no way to grow it back once it wears down. What you have at eighteen is largely what you get. So keeping it intact is more or less the whole game.

Enamel starts to soften and dissolve when the pH in your mouth drops below about 5.5. That’s the number every dentist has memorized. Above it, saliva can actually push minerals back into your teeth (a process called remineralization). Below it, minerals leach out. Your mouth is doing this dance, in miniature, every time you eat or drink anything.

• Plain water: pH 7. Neutral. Your enamel is thrilled.
• Plain sparkling water: pH ~5–6. Slightly acidic because carbonation makes carbonic acid, but usually above the danger line.
• Diet Coke / Coke Zero: pH ~3.0–3.2. This is near-vinegar territory. Your enamel is not thrilled.
• Regular Coca-Cola: pH ~2.5. Cavities and erosion — the worst of both worlds.
• Flavored seltzer (LaCroix, Bubly, Spindrift): varies wildly. Citrus flavors have been measured close to pH 3, which is unnervingly close to soda.

Why does any of this matter more than the average “watch your sugar” advice? Because unlike a cavity — which we can drill out, clean, and fill — enamel that has been eroded away is gone for good. There is no filling for it. Advanced erosion means veneers or crowns, which are wonderful when needed but not something anyone should be signing up for at forty because of a fifteen-year LaCroix habit. Prevention is genuinely cheaper than fixing it later, and this is one of the few places in dentistry where a small change in daily habit really does move the needle over a decade.

The brand-new science (July 2026)

Purdue researchers just published a small but tidy study — presented at NUTRITION 2026 — that measured salivary pH in real time as adults drank soda, plain sparkling water, calcium-fortified sparkling water, and still water. This is a better kind of study than most: instead of measuring the pH of a drink sitting in a beaker, it measured what actually happened inside a mouth.

• Soda caused the biggest and longest pH drop — still measurably acidic twenty minutes later.
• Plain sparkling water caused only a brief pH dip. Saliva restored normal conditions within about twenty minutes.
• Critically, plain sparkling water did not push mouth pH below 5.5 in this study. Saliva did its job.

The lead researcher’s exact line: “replacing sugar-sweetened sodas with unsweetened sparkling water may help lower the risk of enamel erosion.” That is about as close as a scientist ever gets to writing a permission slip.

Why diet soda is genuinely worse (even without the sugar)

If you swapped Diet Coke for sparkling water and quietly wondered whether the two are basically the same acidic thing, the answer is no — they are not remotely the same. Diet sodas drop the sugar, which removes the cavity-feeding side of the equation. But they keep the phosphoric acid and citric acid, which are the drivers of enamel erosion.

Your teeth can be attacked two different ways, and they are worth keeping straight:

1. Cavities — sugar feeds bacteria in dental plaque, bacteria ferment it into acid, acid drills a hole through your enamel over months. Cavities are localized: a hole here, a hole there.
2. Erosion — acid dissolves enamel directly, no bacteria required. Erosion is global: it thins the whole enamel layer, especially on the front and biting surfaces. Shows up as thinning, cold sensitivity, and yellowing at the edges of your front teeth (the yellower dentin underneath starting to show through).

Regular soda gets you both. Diet soda gets you erosion without the cavities. Plain sparkling water gets you neither, mostly. This is why the swap is genuinely a win — you didn’t trade one enamel-killer for another. You traded a soda for something that lives comfortably above the danger line.

The sneaky one: flavored seltzer

Flavored seltzers are the middle ground almost nobody warns you about. A 2016 study in the Journal of the American Dental Association found that citrus-flavored waters could hit pH ~3 — comparable to Coca-Cola. That does not mean your LaCroix is soda in disguise. It means the pattern of use matters:

• Nursing a citrus seltzer at your desk for three hours is a mildly bad idea.
• Drinking the same can with lunch, in ten minutes, is essentially fine.
• Not all flavors are equal. Straight lime and lemon are the worst offenders; the subtle “essence-of-something” flavors are usually gentler.

Reading the can: how to spot an acidic seltzer

If you’re a serial seltzer drinker, a five-second look at the ingredient list tells you most of what you need to know. Three things to check on the label:

• Citric acid listed as an ingredient is the single strongest tell. Anywhere it appears, assume the pH is meaningfully lower than the “just carbonated water” version. This includes many drinks marketed as “hard seltzers” and most citrus-forward flavors.
• “Natural flavors” is not a free pass. Natural citric acid, extracted from actual citrus, still lowers pH the same way. If the flavor is bright and puckery, there’s acid in there — natural or not.
• Calcium-fortified sparkling waters exist and are slightly friendlier to enamel; the calcium doesn’t neutralize the acid, but it gives your saliva a head start on remineralization. Not a magic bullet, but a small edge if the brand is otherwise a favorite.

What actually decides your risk

It is not really what you drink. It is how. The variables that decide whether a habit is a rounding error or a long-term erosion problem:

• Sipping vs. drinking. A single can consumed in ten minutes is a rounding error. The same can nursed for three hours is a three-hour acid bath. If you are a serial sipper at your desk, this is the single most useful change to make.
• With food, not alone. Meals boost saliva flow and physically buffer acid. A can with lunch is meaningfully less erosive than the same can at 3 PM by itself.
• Do not brush right after. Enamel is temporarily softened for about 20–30 minutes after anything acidic. Brushing during that window scrubs softened enamel and accelerates wear. Wait at least 30 minutes, or rinse with plain water in the meantime.
• Straws help — modestly. They aim the liquid past the front teeth (the ones erosion is most visible on).
• Chew sugar-free gum (xylitol if you can find it) after acidic drinks to jump-start saliva.
• Daily fluoride toothpaste is the boring but genuinely important habit. If you already have real wear, ask about a prescription-strength (5000 ppm) paste.

Who should actually worry

Almost nobody who drinks a plain sparkling water or two a day. If that is you, close this tab and go enjoy your bubbles. Worry more if any of these fit:

• You sip citrus-flavored seltzer or diet soda more or less constantly through the workday.
• You have acid reflux (GERD) or dry mouth — some common medications (antidepressants, antihistamines) dry the mouth and remove your best natural defense.
• You are noticing new cold sensitivity, yellowing at the edges of your front teeth, or front-tooth edges that look slightly see-through. Those are the classic tells for erosion, not cavities.
• You have kids doing the same thing — young enamel is still maturing and is more vulnerable than adult enamel.

What early erosion actually looks like

Erosion is quiet until it isn’t. It rarely hurts in the early stages, which is why so many patients arrive already in the moderate-to-advanced range. If you want a two-minute self-check in a bathroom mirror, this is what to look for:

• Thinning edges on the top front teeth. The biting edge starts to look slightly translucent or see-through — sometimes with a faint bluish tinge — because there’s no dentin behind that thin edge, just enamel getting thinner.
• Cupping on the back teeth. Small dished-out craters on the biting surfaces of your molars. Run your tongue across them; they feel smooth and scooped rather than the normal ridges and grooves.
• Yellowing that whitening won’t fix. As enamel thins, the yellower dentin underneath shows through. If you’ve tried whitening strips and the shade barely budged, this is a common reason why.
• New sensitivity to cold air or cold drinks. Often the first symptom that gets a patient to book, and usually a sign that the erosion has progressed enough for the underlying layer to be involved.

The good news: caught early, erosion is very manageable — fluoride, habit tweaks, sometimes a bite-guard if there’s grinding on top of it. Caught late, it’s restorative work. The gap between “very manageable” and “restorative” is usually a few years of small habits, not a dramatic event.

The five-second version

• ✅ Plain sparkling water: basically fine. Enjoy.
• ⚠️ Flavored seltzer: fine with meals, risky as an all-day desk drink.
• 🚫 Diet soda: not the enamel-safe hack it looks like. Cut down.
• 🚫 Regular soda: the worst of both worlds. Cavities and erosion.
• 🧠 The rule: it is not what you drink, it is how long you sip it and whether you brush too soon after.

If you drink sparkling water (or diet soda) daily and you are starting to notice yellowing at the edges of your front teeth, thinning, or new cold sensitivity — that is what enamel erosion looks like, and it is worth an exam. Come in and we will give you a straight answer.

Related reading on this site: whitening · veneers · back to the journal