The Science of Soda Acidity
The acidity of beverages, measured on the pH scale, is a critical factor in dental erosion. The pH scale runs from 0 to 14, where 7 is neutral. Anything below 7 is acidic, and anything above is basic. For context, stomach acid is highly acidic (pH 1.5-3.5), while water is neutral (pH 7.0). A significant concern for dental health is that tooth enamel begins to soften and dissolve at a pH of approximately 5.5. This means that even the least acidic sodas, which typically have a pH below 5.5, still pose a threat to dental health.
Carbonation and Carbonic Acid
One primary source of acidity in all carbonated soft drinks is the carbonation itself. The process involves dissolving carbon dioxide (CO2) in water under pressure. This creates carbonic acid (H2CO3), a weak acid that lowers the beverage's pH. While weak, it is still an acidic component that contributes to enamel erosion. This is why even plain sparkling water is more acidic than still water.
Acidic Additives
Beyond carbonation, many sodas contain additional acids to enhance flavor and serve as preservatives. Two of the most common are phosphoric acid and citric acid. Phosphoric acid is frequently used in cola drinks and is known for significantly lowering pH levels. Citric acid is common in fruit-flavored and lemon-lime sodas to provide a tart taste. Root beer, the least acidic of common sodas, often lacks these two strong acids, which is its key advantage.
The Least Acidic Soda: Root Beer
Among the lineup of popular soft drinks, root beer consistently ranks as the least acidic option. A study found Mug brand root beer to have a pH of 4.038, while Barq's root beer was measured at 4.11. This is significantly higher (less acidic) than cola drinks, which often hover around pH 2.5. The reason for root beer's reduced acidity is its ingredient profile; it typically contains no phosphoric acid and only minimal citric acid. Furthermore, some brands of root beer are non-carbonated, which further reduces their acid content.
Diet Sodas and Acidity
It is a common misconception that diet or sugar-free sodas are less harmful to teeth. While they eliminate the sugar component that fuels bacteria, they remain highly acidic due to the inclusion of acids like citric and phosphoric acid to enhance flavor and preserve the product. The pH levels for many diet sodas are still dangerously low for enamel health. For instance, Diet Coke has a pH of around 3.1 to 3.3, while regular Coke is closer to 2.5. However, some diet versions are indeed less acidic than their sugary counterparts. For example, Diet A&W Root Beer has a notably higher pH of 4.57 compared to the regular version's 4.27.
Comparison of Soda Acidity (pH)
| Beverage Type | Specific Example | Approximate pH | Additional Notes |
|---|---|---|---|
| Least Acidic Soda | A&W Diet Root Beer | 4.57 | Generally less acidic due to lack of phosphoric and citric acids. |
| Moderately Acidic Soda | Mountain Dew | 3.22 | Contains high levels of citric acid. |
| Highly Acidic Soda | Coca-Cola | 2.37-2.52 | Contains phosphoric acid. |
| Highly Acidic Soda | RC Cola | 2.38 | Contains phosphoric acid. |
| Slightly Acidic Carbonated Water | Canada Dry Club Soda | 5.24 | Significantly less acidic than soft drinks, but still acidic. |
Tips for Minimizing Acid Damage
Since even the least acidic soda is still damaging to enamel, mitigating the harm is important. Here are some strategies to protect your teeth when consuming soda:
- Use a straw: Drinking through a straw can minimize the contact of the acidic liquid with your teeth, especially the front teeth.
- Drink quickly: Do not sip soda slowly over a long period. Prolonged exposure increases the time your enamel is bathed in acid.
- Rinse with water: After finishing your soda, rinse your mouth with plain water to help wash away the acid and return your mouth to a more neutral pH.
- Wait to brush: Avoid brushing your teeth for at least 30 minutes to an hour after drinking soda. Brushing when your enamel is softened by acid can cause further abrasion and damage.
- Follow up with water or milk: Drinking a glass of water afterward helps neutralize the acids. Milk also has a near-neutral pH and is rich in calcium, which can benefit tooth remineralization.
Conclusion: The Bottom Line on Acidic Drinks
Ultimately, while root beer is demonstrably the least acidic of popular soft drinks, it is not non-acidic and still poses a risk to tooth enamel. The most effective way to protect your dental health from the effects of acidic beverages is to limit or avoid their consumption altogether. For those who choose to indulge, opting for a brand of root beer, using a straw, and practicing good oral hygiene can help minimize potential damage. When looking for the best option, remember that all sodas, even diet and clear varieties, are significantly more acidic than plain water. For a truly low-acid choice, unsweetened coconut water or regular tap water is always the best bet.
