Phosphoric acid and infection-related urinary stone formation in lab tests
What it found
In artificial urine, phosphoric acid made stone-forming minerals appear earlier but formed less solid material overall.
These effects were seen only when infection-causing bacteria or their byproducts were present.
What they found
Animal and lab studies
Earlier mineral formation
In artificial urine, adding phosphoric acid caused stone minerals to start forming at a lower pH than normal. This happened both with live bacteria and when bacterial activity was mimicked with ammonia.
Less solid material overall
Higher amounts of phosphoric acid led to less total solid material forming in the artificial urine. The drop in solid material did not match the acid amount exactly.
Larger clumps formed
Under the microscope, the solid particles in artificial urine looked more clumped together when phosphoric acid was present. Larger clumps could be harder for the body to flush out naturally.
Infection required for effect
Without infection-causing bacteria or simulated bacterial activity, phosphoric acid did not cause these stone minerals to form in the artificial urine. The authors note this effect only happens during a urinary tract infection.
What the authors conclude
- They conclude that phosphoric acid makes infection-related stone minerals start forming earlier in urine, which they consider an unfavourable effect.
- They also note that the acid reduces the total amount of solid material formed, which they view as a positive outcome.
- The authors advise that these effects only matter when urease-producing bacteria are present in the urinary tract.
How it was done
Urinary stones linked to infections are becoming more common in wealthy countries, possibly due to highly processed foods. Phosphoric acid is widely used as an acidity regulator in drinks and foods, so the authors wanted to see if it affects how these stones form.
The researchers tested four concentrations of phosphoric acid in artificial urine at body temperature for up to 24 hours. They ran the tests both with live bacteria taken from a human stone and without bacteria, using ammonia to mimic bacterial activity. Each test was repeated at least three times.
What it can’t tell you
- These experiments used artificial urine in glassware, not real human bodies. Lab results cannot show what actually happens inside a person drinking phosphoric acid.
- The study measured how quickly minerals appeared and how much formed, but it did not track whether people get more stones from consuming this ingredient.
Who paid
- Conflicts
- The authors have declared that no competing interests exist.
- Authors work at
- Lodz University of Technology, Poland; Jan Długosz University of Czestochowa, Poland; University of Lodz, Poland
The paper
- Title
- Phosphoric Acid Versus Biogenic Mineralization of Hydroxyapatite and Carbonate Apatite in Relation to Infection-Induced Urinary Stones: Physical, Chemical and Microbiological Aspects
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Prywer J, Mielniczek-Brzóska E, Torzewska A (2025). Phosphoric Acid Versus Biogenic Mineralization of Hydroxyapatite and Carbonate Apatite in Relation to Infection-Induced Urinary Stones: Physical, Chemical and Microbiological Aspects. ChemPlusChem. doi:10.1002/cplu.202400712Free full textPubMed 40028826DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error