Soda pop often contains phosphoric acid, which is added to improve shelf life and give carbonated drinks a crisp and tangy taste. Phosphoric acid content varies quite a bit from brand to brand, although the majority of diet and regular sodas contain it, especially colas. Phosphorus is a mineral essential for health, but consuming phosphoric acid via soda pop can lead to health issues and is likely bad for you in large quantities.
Phosphorus and Phosphoric Acid
Phosphorus is found in many foods. Once consumed, most of it gets deposited in bones and teeth, but your body also needs it for normal muscle contraction, energy production and hormone synthesis. The kidneys help maintain appropriate levels of phosphorus in your body because too much in the blood causes problems. In contrast, phosphoric acid contains phosphorus in the form of phosphate. It exists naturally in foods such as meat and dairy, but the type added to soda pop is synthesized. Phosphoric acid is added to soft drinks to retard the growth of molds and bacteria in sugary formulas and to provide a sharper after-taste.
Consumption of soda pop is linked to loss of calcium from bones. Research over the last couple of decades suggests that high phosphorus intake from drinking soft drinks leaches bones and teeth of calcium because calcium is attracted to high phosphorus concentrations in the bloodstream. Consequently, soda pop consumption is linked to higher risk of bone fractures, even in teenagers, and increased risk of developing osteoporosis. Minerals such as calcium provide strength and density to bones, so reduced mineralization leads to weak or brittle bones. Another factor why drinking sodas may weaken bone is that it often replaces calcium-rich milk in the diets of children and teenagers. In addition, caffeine can interfere with calcium absorption and contribute to lower bone density.
In addition to loss of calcium, the acidity and corrosive nature of phosphoric acid negatively impacts the protective covering on teeth called enamel. The pH measure of most soda pop is below 3, which is on par with vinegar or acetic acid. Sugar and other acids in soda pop contribute to acidity, but phosphoric acid is the primary factor. Phosphoric acid oxidizes or corrodes the tooth enamel on contact, although exposure time and dental hygiene are obviously important factors. In addition, the high sugar content of most sodas, often in the form of high fructose corn syrup, is strongly linked to tooth decay, gingivitis and the formation of cavities.
People who drink two or more colas per day have significantly higher risk of developing kidney disease and kidney stones compared to people who don’t drink any soda pop. High levels of blood phosphorus overwork the kidneys, which may lead to damage and dysfunction. Soda water without phosphoric acid, on the other hand, does not increase your risk of kidney problems. Carbonated soda water primarily contains carbonic acid and sometimes citric acid, but often little or no phosphoric acid. Citrus-flavored sodas contain much more citric acid and sometimes no phosphoric acid, but it depends on the manufacturer. A typical 12-ounce can of cola contains about 60 milligrams of phosphorus, whereas daily limits for people with healthy kidneys range between 1,500 and 2,000 milligrams of phosphorus.
- Contemporary Nutrition: Functional Approach; Gordon M. Wardlaw, et al.
- Public Health Nutrition: From Principles to Practice; Mark Lawrence, et al.
- Textbook of Functional Medicine; David S. Jones
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.