Which soft drink is the most acidic?: Unpacking the pH levels and dietary impact on your health

October 13, 2025 •

3 min read

According to the Academy of General Dentistry, tooth enamel starts to dissolve at a pH of 5.5, while many soft drinks fall well below this mark, causing significant damage over time. This raises a critical question for those concerned with their diet and overall health: which soft drink is the most acidic?

Quick Summary

Studies show RC Cola is often cited as the most acidic soft drink, but many colas and citrus-flavored beverages have extremely low pH levels due to added acids like phosphoric and citric acid. Regular consumption severely impacts dental health, leading to enamel erosion and a higher risk of decay.

Key Points

RC Cola is often the most acidic: Studies repeatedly cite RC Cola as having one of the lowest pH levels among soft drinks, often below 2.5.
Acids cause the problem: The primary acidifying agents in soft drinks are phosphoric acid in colas and citric acid in citrus-flavored sodas.
Diet sodas are still highly acidic: Despite containing no sugar, diet versions of colas and other soft drinks still have very low pH levels due to added acids, posing a risk to tooth enamel.
Acidity erodes tooth enamel: At a pH of 5.5, tooth enamel begins to dissolve; frequent exposure to more acidic drinks can cause irreversible damage.
Minimize health impacts with smart habits: You can reduce damage by drinking in moderation, using a straw, and rinsing with water after consumption.

The pH Scale and Soft Drink Acidity

The pH scale is used to measure the acidity or basicity of a substance, ranging from 0 to 14. Pure water has a neutral pH of 7; substances with a pH below 7 are acidic, and those above 7 are basic. A difference of one whole number on the scale represents a tenfold change in acidity. Many soft drinks are quite acidic, often having pH levels comparable to common household items. This high acidity is primarily caused by added phosphoric acid and citric acid.

The Culprits: Phosphoric and Citric Acids

Phosphoric Acid: Commonly found in colas, phosphoric acid provides a sharp taste and acts as a preservative. High consumption may be linked to reduced bone mineral density and kidney issues.
Citric Acid: Frequently used in citrus-flavored sodas, citric acid offers a tart flavor and helps preserve freshness. However, high concentrations can significantly damage dental enamel.

The Most Acidic Soft Drink: RC Cola Takes the Lead

Research from various dental studies and publications like the Academy of General Dentistry and Live Science often identifies RC Cola as the most acidic soft drink, with a pH reported to be as low as 2.387. Other colas are also highly acidic, contributing to their erosive potential. It's worth noting that specific pH values can fluctuate depending on testing methods and individual batches.

Comparison Table of Common Beverages by Acidity


Beverage Type	Example Brands	Approximate pH Range	Primary Acid(s)	Oral Erosive Potential
Most Acidic Soft Drink	RC Cola	2.3–2.5	Phosphoric acid	Extremely high
Other Colas	Coca-Cola Classic, Pepsi	2.37–2.53	Phosphoric acid	Extremely high
Citrus-Flavored Sodas	Mountain Dew, Sprite	3.2–3.3	Citric acid	High
Diet Colas	Diet Pepsi, Diet Coke	3.0–3.3	Phosphoric acid	High (no sugar, but still very acidic)
Root Beer	A&W Root Beer	4.1–4.6	None (often), flavorings	Minimally erosive (among sodas)
Tap Water	Local supply	~7.0	None	None

Nutritional and Health Implications of Acidic Soft Drinks

The high acidity of soft drinks is particularly harmful to oral health. Tooth enamel begins to demineralize at a pH of 5.5, meaning that acidic beverages can erode the protective layer of teeth, leading to various dental problems.

Oral Health Risks

Enamel Erosion: The outermost layer of your teeth, enamel, is susceptible to acid attacks, which can cause thinning, sensitivity, discoloration, and an increased risk of cavities.
Increased Sensitivity: As enamel erodes, the underlying dentin becomes exposed, leading to sensitivity to hot and cold.
Increased Risk of Cavities: Even sugar-free sodas weaken enamel with their acidity, making teeth more vulnerable to decay from other sources.

Other Potential Health Concerns

Beyond dental issues, frequent consumption of phosphoric-acid-containing colas may be associated with other health problems:

Kidney Problems: Some research suggests that consuming two or more colas daily might increase the risk of chronic kidney disease, potentially due to the high phosphorus load.
Bone Health: While more research is needed, there is a theoretical concern that high phosphate intake could negatively impact calcium absorption and bone mineral density.

How to Mitigate the Damage

If you consume soft drinks, you can take steps to minimize their negative impact on your health:

Drink in Moderation: Reduce the frequency and amount of soft drinks you consume to limit acid exposure.
Use a Straw: Drinking through a straw can help reduce contact between the soda and your teeth.
Rinse with Water: Swishing water in your mouth after drinking soda can help neutralize acids and wash away residue.
Avoid Brushing Immediately: Wait at least 30-60 minutes after drinking an acidic beverage before brushing to allow saliva to help re-harden enamel.
Choose Less Acidic Options: If you're going to have a soft drink, consider options like root beer, which typically has a higher pH and is less erosive.

Conclusion

Many popular soft drinks, including RC Cola, have high acidity levels that pose risks to both oral and general health. Understanding the role of acids like phosphoric and citric acid is crucial for making informed dietary choices. By practicing moderation and employing protective strategies, individuals can reduce the damaging effects of these beverages. Prioritizing less acidic alternatives supports better long-term health.

For more information on how different beverages affect salivary pH, you can consult research like this study from SciELO.br: Titratable acidity of beverages influences salivary pH recovery.

Frequently Asked Questions

Coca-Cola is more acidic than Mountain Dew. According to some measurements, Coca-Cola has a pH of around 2.5, while Mountain Dew has a pH closer to 3.2, making Coke significantly more acidic.

Soft drinks are acidic due to the addition of various acids, such as phosphoric acid (found in colas) and citric acid (found in citrus sodas). These acids are used for flavoring, preservation, and to add a tangy, sharp taste.

While diet soft drinks don't contribute to sugar-related cavities, they are often just as, or nearly as, acidic as their regular counterparts. This high acidity can still cause significant tooth enamel erosion over time, making them equally harmful to dental health in this regard.

Root beer, especially certain brands like A&W, is generally the least acidic soft drink option. It often lacks the potent phosphoric or citric acids found in other sodas and has a higher pH.

To protect your teeth, drink soft drinks in moderation, use a straw to minimize contact with your teeth, and rinse your mouth with water immediately afterward. Also, avoid brushing your teeth for at least 30 to 60 minutes after consuming an acidic beverage to allow saliva to neutralize the acids.

Yes, temperature can affect pH. Studies have shown slight variations in the pH of soft drinks when refrigerated versus at room temperature, though both are still highly acidic.

Yes, the carbonation process involves dissolving carbon dioxide gas in water, which forms carbonic acid and slightly lowers the pH. However, the added phosphoric or citric acid is typically a much stronger contributor to the overall acidity.