Unsweetened sparkling water may be safer for teeth than soda

Findings from a new study comparing the effects of different beverages on mouth acidity suggest that unsweetened sparkling water may be better for your teeth than sugar-sweetened soda.

When the mouth's pH drops below about 5.5, acids begin to dissolve tooth enamel. The new study looked beyond beverage acidity itself and showed that although sparkling water lowers the mouth's pH, it does so less than soda.

Many people are switching from soda to sparkling water, and our findings suggest that unsweetened sparkling water may be a lower-risk alternative to soda, when consumed in moderation and alongside good oral hygiene practices."

Wajiha Zulfiqar, graduate student in Nutrition Science, Purdue University

Zulfiqar will present the findings at NUTRITION 2026, the flagship annual meeting of the American Society for Nutrition, held July 25–28 in National Harbor, Maryland, just outside Washington, D.C.

Although studies have shown that sugar-sweetened soda can contribute to dental erosion by lowering the pH in the mouth below 5.5, less is known about how unsweetened sparkling waters affect oral acidity.

To find out more, the researchers measured how sugar-sweetened soda, regular sparkling water, calcium-fortified sparkling water and plain water affected mouth acidity - or salivary pH - in 20 adults. They used the same study participants for all the beverages to help minimize differences between individuals that could affect results.

"Directly comparing different beverages using the same experimental framework allowed us to evaluate the effects of sparkling water relative to both soda - a higher-risk beverage - and plain water as a neutral reference," said Zulfiqar. "Additionally, by measuring how the mouth responded in real time, rather than only testing beverage acidity alone as other studies have done, our study provides a more realistic understanding of how these drinks may impact oral health."

The researchers found that the soda made the mouth the most acidic, leading to a salivary pH that was significantly lower than that of water at both 2 and 20 minutes after consumption. Unsweetened sparkling water without calcium caused a temporary decrease in salivary pH at 2 minutes, whereas calcium-fortified sparkling water showed a decrease at 5 minutes. For both beverages, salivary pH returned to near baseline levels by 20 minutes.

They also found that, after consuming both the soda and the sparkling waters, saliva quickly restored the mouth's acidity to normal, keeping pH above the level that causes enamel damage. The researchers note that the study only measured short-term changes in salivary pH. In real life, the potential for enamel damage depends on factors such as the frequency of consumption, duration of exposure and sugar content.

"Our results suggest that replacing sugar-sweetened sodas with unsweetened sparkling water may help lower the risk of enamel erosion," said Zulfiqar. "The results also highlight an opportunity for the beverage industry to explore reformulation strategies that could potentially reduce the erosive potential of acidic beverages."

Next, the researchers plan to test how sparkling water influences oral health over the long term, which will help reveal whether it changes other aspects of the mouth environment that are important to good oral health.