Sparkling water appears less harsh on teeth than soda

Unsweetened sparkling water caused a smaller and shorter-lasting shift in mouth acidity than sugary soda in a small study. The result points to it as a potentially lower-risk choice for teeth, though the experiment did not assess long-term dental damage.

Researchers at Purdue University compared four drinks in 20 adults and measured saliva acidity after each one. Because every participant tried the same beverages, the team was able to account for natural differences between individuals.

The findings were presented at NUTRITION 2026, the American Society for Nutrition’s annual meeting. They were preliminary conference results and had not yet gone through the peer-review process needed for a full journal article at the time.

The beverages studied were sugar-sweetened soda, regular unsweetened sparkling water, calcium-fortified sparkling water and plain water. The researchers aimed to see what happens inside the mouth, rather than judging the drinks only by their acidity in a container.

Acidity is measured with pH, a scale in which lower numbers indicate more acidic conditions. Tooth enamel can begin to break down in sufficiently acidic environments, and a pH of about 5.5 is often used as a reference point.

That said, beverage acidity by itself does not fully predict what happens to teeth. Saliva helps dilute and neutralize acid, so tracking its response offers another way to understand what follows a drink.

Soda produced the biggest rise in mouth acidity. Relative to plain water, saliva pH was significantly lower two minutes and 20 minutes after participants drank the soda.

Regular sparkling water caused a brief drop in pH after two minutes. The calcium-fortified version showed a decrease after five minutes, and both sparkling waters returned close to their starting levels within about 20 minutes.

The researchers said the short-term saliva readings stayed above the level associated with enamel damage. In other words, the study showed differences in acidity, but it did not directly show that any of the drinks eroded participants’ teeth during the test.

Longer-term effects may depend on how often the drinks are consumed, how long they stay in contact with teeth and whether they contain sugar. The results for unsweetened sparkling water should not automatically be extended to every flavored or sweetened carbonated drink.

The study was also small and looked only at a short window after drinking. Researchers plan to examine oral-health effects over a longer period, which would offer stronger evidence about whether the observed pH differences lead to meaningful differences in dental erosion.

For now, the findings help distinguish unsweetened sparkling water from sugary soda without labeling it harmless in every situation. The main advance is a direct comparison of the mouth’s response, with longer studies still needed to show what it means for teeth over time.

For broader related reading, please see articles about The truth about diet soda: is it really bad for you?, and How to have the no-sugar diet for better health.

For more information, please see articles about Sugary drinks strongly increase heart disease risk, study finds, and Understanding ultra-processed foods: What you need to know.

Source: American Society for Nutrition.