E338

Phosphoric acid

  • Our verdict: 4 - we recommend avoiding
  • Latest update & fact check: 2024.8.2 - Rebecca Taylor, CNP
  • Origin: It is produced synthetically and does not come from natural sources.

Phosphoric acid, known by the additive code E338, is colourless, odourless and has a sharp, sour taste. It is a mineral acid with the chemical formula H₃PO₄. It is highly soluble in water, which makes it useful in a variety of applications, particularly in the food and beverage industry. Phosphoric acid is used to acidify foods and beverages, imparting a bitter or sour taste, and serves as a preservative. It is commonly found in dark sodas such as cola.

Origin

Phosphoric acid is mainly of artificial origin. It is industrially produced by two main methods: a thermal process and a wet process. The thermal process involves burning elemental phosphorus to form phosphorus pentoxide, which is then hydrated to phosphoric acid. The wet process involves the treatment of phosphate rock with sulphuric acid, resulting in the formation of phosphoric acid and calcium sulphate (gypsum) as a by‑product.

Characteristics and uses in the food industry

Phosphoric acid is used in food processing for several reasons:

  • Acidity regulator: It helps maintain the desired pH level in food and beverages.
  • Flavour enhancer: Provides a tart taste commonly found in soft drinks.
  • Preservative: Inhibits the growth of mold and bacteria, thereby extending the shelf life of products.
  • Emulsification: Helps mix oil and water components, improving texture and consistency.

Use in ultra‑processed foods

Phosphoric acid is commonly found in a wide range of ultra‑processed foods due to its multifunctional properties:

  • Carbonated beverages: one of the most common uses of phosphoric acid is in carbonated soft drinks. It provides the sharp, tart taste that is typical of these beverages and helps stabilize carbonated water.
  • Processed meats: Used in processed meats to retain moisture and improve texture. Phosphoric acid helps emulsify fats and proteins, giving products like sausages and sausage a consistent texture.
  • Bakery products: In bakery products, phosphoric acid can act as a leavening agent in combination with baking soda. It helps in the chemical reaction that produces carbon dioxide, which causes the dough to rise.
  • Cheese and dairy products: It helps to adjust the acidity of cheese, improving taste and texture. It also helps prevent fat separation in dairy products.
  • Canned foods: Acts as a preservative in canned foods, preventing spoilage by inhibiting the growth of microorganisms.

Effects on health

Although phosphoric acid is generally considered safe when consumed in moderate amounts, there are potential health aspects and risks associated with excessive intake:

  • Dental health: phosphoric acid can contribute to tooth enamel erosion and cavities due to its high acidity, especially when consumed in excess in soft drinks.
  • Bone health: High intake of phosphoric acid, especially from soft drinks, has been associated with lower bone mineral density. This may be attributed to an imbalance of calcium and phosphorus levels in the body, which can lead to weakened bones.
  • Kidney health: Excessive consumption of phosphoric acid may increase the risk of kidney damage and contribute to kidney stones.
  • Electrolyte imbalances: High levels of phosphorus can lead to electrolyte imbalances, which can affect cardiovascular health and overall body function.
  • Insulin resistance: High phosphoric acid intake, especially from sugary soft drinks, has been associated with an increased risk of insulin resistance. Insulin resistance is a condition in which the body's cells are less responsive to insulin, leading to elevated blood sugar levels and an increased risk of developing type 2 diabetes.
  • Obesity: Consumption of drinks containing phosphoric acid, especially sugary sodas, is associated with weight gain and obesity. These beverages are high in empty calories and may contribute to increased caloric intake without providing essential nutrients.
  • Gastrointestinal irritation: phosphoric acid is highly acidic and can irritate the lining of the gastrointestinal tract. This can lead to symptoms such as stomach pain, nausea and discomfort, especially in individuals with pre‑existing conditions such as reflux or gastritis.
  • Microbiota imbalance: the acidic nature of phosphoric acid can alter the pH of the intestinal environment. This can potentially upset the balance of the gut microbiota, which is the community of beneficial bacteria in the digestive tract. A disrupted microbiota is associated with a variety of health problems, including digestive problems, compromised immune function and inflammatory conditions.
  • Digestive enzyme function: high acidity can affect the activity of digestive enzymes, which require a specific pH range to function optimally. This can potentially impair digestion and nutrient absorption.

Sources

  1. Food and Agriculture Organization of the United Nations (FAO): Food Additives Database.
  2. World Health Organization (WHO): Guidelines for the safe use of food additives.
  3. National Institutes of Health (NIH): Phosphoric acid and its impact on health.
  4. Touger‑Decker, R., & van Loveren, C. (2003). Sugars and dental caries. American Journal of Clinical Nutrition, 78(4), 881S‑892S. Available at: American Journal of Clinical Nutrition
  5. Calvo, M. S., & Tucker, K. L. (2013). Is phosphorus intake that exceeds dietary requirements a risk factor in bone health? Annals of the New York Academy of Sciences, 1301(1), 29‑35. Available at: Annals of the New York Academy of Sciences
  6. Karp, H. J., Ketola, M. E., Lamberg‑Allardt, C. J. (2007). Acute effects of calcium phosphate and calcium carbonate on markers of calcium and bone metabolism in young women. British Journal of Nutrition, 96(2), 438‑444. Available at: British Journal of Nutrition
  7. Heaney, R. P., & Layman, D. K. (2008). Amount and type of protein influences bone health. American Journal of Clinical Nutrition, 87(5), 1567S‑1570S. Available at: American Journal of Clinical Nutrition
  8. Schulze, M. B., Manson, J. E., Ludwig, D. S., et al. (2004). Sugar‑sweetened beverages, weight gain, and incidence of type 2 diabetes in young and middle‑aged women. Journal of the American Medical Association, 292(8), 927‑934. Available at: JAMA
  9. Pereira, M. A., Fulgoni, V. L. (2010). Consumption of high‑fructose corn syrup in beverages may play a role in the epidemic of obesity. American Journal of Clinical Nutrition, 89(2), 537‑543. Available at: American Journal of Clinical Nutrition