Phosphoric acid is an inorganic compound used widely in the food and beverage industry, primarily functioning as an inexpensive food additive. It is included in many products to provide a sharp, tangy, or sour taste, and also acts as a preservative by inhibiting the growth of mold and bacteria. The presence of this acid makes consumables highly acidic, which directly poses a threat to the protective layer of teeth. Therefore, phosphoric acid is damaging to teeth due to its corrosive nature on dental enamel.
How Phosphoric Acid Attacks Tooth Enamel
The damage caused by phosphoric acid is a chemical process known as dental erosion, which occurs when the acid dissolves the mineral structure of the tooth. Enamel, the hardest substance in the human body, is primarily composed of calcium and phosphate minerals, forming a crystal structure called hydroxyapatite. The acid in beverages lowers the pH level in the mouth significantly, creating an environment hostile to the enamel.
Acidity is measured on the pH scale, and enamel begins to demineralize when the pH drops below the critical pH threshold, which is approximately 5.5. Many beverages containing phosphoric acid have pH levels well below 4.0, making them highly erosive to the enamel. When the acid encounters the tooth surface, hydrogen ions chemically strip away the calcium and phosphate ions from the hydroxyapatite crystals.
The mouth’s natural defense mechanism is saliva, which contains its own calcium and phosphate ions and is slightly alkaline, working to neutralize acids and promote remineralization. However, with frequent or prolonged exposure to strong acids like phosphoric acid, the demineralization process outpaces the natural ability of saliva to repair the enamel. This continuous loss of minerals weakens the outer layer of the tooth, leading to sensitivity and an increased risk of cavities.
Common Dietary Sources of Phosphoric Acid
The most concentrated and common source of phosphoric acid in the modern diet is carbonated soft drinks, particularly dark colas. This includes both regular and diet versions, as the acid is added for flavor and preservation, not just to offset the sugar content. The combination of carbonation and phosphoric acid contributes to the drink’s overall high acidity.
Phosphoric acid is also used in other processed foods and beverages where a sharp taste or extended shelf life is desired. These sources include bottled iced teas, certain flavored waters, and some energy or sports drinks. Beyond beverages, it is found as an additive in certain processed cheeses, such as cottage cheese, and in quick-setting gelatin products.
In these food items, the acid or its derivatives are used as acidulants, emulsifiers, or stabilizers. Since the ingredient is not limited to one food group, it is easy to consume erosive substances frequently. Identifying these common dietary sources is the first step in mitigating potential damage.
Practical Steps to Reduce Acid Damage
Since phosphoric acid exposure is widespread, limiting the frequency and duration of contact with the teeth is the most effective preventative strategy. When consuming acidic beverages, it is better to drink them quickly at mealtime rather than sipping slowly over a long period. This reduces the total time the tooth enamel is subjected to the low pH environment.
Using a straw for acidic drinks can help channel the liquid past the front teeth and minimize contact with the enamel surface. Positioning the straw toward the back of the mouth provides the greatest benefit, although it does not eliminate all exposure. This simple habit can significantly reduce the risk of localized erosion.
Immediately after consuming an acidic drink, the mouth should be rinsed thoroughly with plain water to wash away residual acid and raise the pH level. This action supports the saliva’s ability to begin the neutralization process more quickly. Avoid brushing teeth immediately after consuming acidic items, as the enamel is temporarily softened and brushing can physically scrub away the vulnerable surface layer.
Dental professionals advise waiting at least 30 to 60 minutes after acid exposure before brushing to allow the enamel time to re-harden. Additionally, finishing an acidic meal or drink with calcium-rich foods like milk or cheese can help. The calcium and phosphate content in dairy products assists in neutralizing the acid and promoting the remineralization of the tooth surface.