Phosphoric acid is a colorless, odorless compound derived from the element phosphorus. This compound is widely used in the food and beverage industry, most notably in dark-colored sodas. The frequent consumption of products containing phosphoric acid has raised questions about its safety and potential long-term effects on human health.
Role of Phosphoric Acid in Processed Foods
Phosphoric acid serves multiple technical functions in processed food production. It is primarily added as an acidulant, providing a sharp, tangy flavor profile that balances the intense sweetness in beverages like cola.
Beyond flavor, it acts as an effective preservative. By lowering the pH level, it creates an acidic environment that inhibits the growth of mold, yeast, and bacteria, significantly extending the shelf life. Consumers most frequently encounter this ingredient in:
- Carbonated soft drinks, especially colas.
- Certain processed meats to retain moisture and improve texture.
- Some bottled teas and jams.
Mineral Balance and Skeletal Health
Phosphorus is an essential mineral, with about 85% residing in the bones, providing strength and rigidity. However, a high intake of the inorganic form found in phosphoric acid can disrupt the body’s natural mineral balance.
Maintaining a specific ratio of phosphorus to calcium is important for healthy bone turnover. When phosphorus intake is excessively high, especially when calcium intake is low, it pulls calcium from the bones into the bloodstream. This mechanism involves the parathyroid hormone, which increases bone resorption to maintain normal blood calcium levels.
Studies correlate high consumption of cola-type sodas (three or more servings per day) with lower bone mineral density, especially in women. This effect is hypothesized to result from both the high phosphoric acid load and the displacement of calcium-rich beverages like milk from the diet.
Kidney Function and Phosphoric Acid Intake
The kidneys are the primary regulators responsible for filtering excess phosphorus from the blood to maintain a healthy balance. Chronic, high consumption of inorganic phosphorus from food additives like phosphoric acid places a substantial metabolic demand on these organs.
The inorganic phosphorus in additives is nearly 100% absorbed, creating a greater load than the organic phosphorus naturally found in whole foods. This increased burden may be linked to an elevated risk of chronic kidney disease (CKD); one study associated consuming two or more colas per day with a higher risk of kidney problems.
For individuals with impaired kidney function, controlling dietary phosphorus is particularly important. High blood levels of phosphorus (hyperphosphatemia) in these patients are associated with an increased risk of cardiovascular disease, as the excess mineral can lead to calcium deposits in soft tissues and blood vessels.
Phosphoric Acid and Dental Erosion
The most direct health effect of phosphoric acid is its chemical impact on the teeth. Its presence in soft drinks results in a low pH, often ranging from 2.3 to 3.9 in commercial beverages. This high acidity directly contributes to dental erosion, which is the dissolution of the tooth’s hard tissue, primarily the enamel.
The acid works by chemically stripping away the mineral structure of the tooth surface. This is a distinct process from dental caries, or traditional cavities, which are caused by bacteria metabolizing sugars and producing acid. Frequent exposure to this low pH environment wears down the enamel, making the teeth sensitive and more susceptible to further damage.
To mitigate the direct acidic attack, simple consumption methods can be helpful. These include using a straw to minimize contact with the teeth or rinsing the mouth with water immediately after consuming a beverage that contains phosphoric acid.