The Claim

Malic acid supplementation at 1200 mg/day for 7 days in healthy adults is associated with a significant increase in urinary supersaturation of hydroxyapatite and tricalcium phosphate due to elevated urinary pH, resulting in a shift in stone composition risk from calcium oxalate to calcium phosphate.

Source: Malic Acid Supplementation Increases Urinary Citrate Excretion and Urinary pH: Implications for the Potential Treatment of Calcium Oxalate Stone Disease

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
30score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

How it works
1 study reviewed
In plain English

Taking 1200 mg of malic acid daily for 7 days increases the levels of hydroxyapatite and tricalcium phosphate in urine and raises urinary pH, which changes the type of kidney stones a person is more likely to form from calcium oxalate to calcium phosphate.

See the scientific wording

Malic acid supplementation at 1200 mg/day for 7 days in healthy adults is associated with a significant increase in urinary supersaturation of hydroxyapatite and tricalcium phosphate due to elevated urinary pH, suggesting a potential shift in stone composition risk from calcium oxalate to calcium phosphate.

Why this might work

When malic acid is consumed, the body breaks it down and produces bicarbonate, which makes the blood and urine less acidic. This change causes more citrate to be released into the urine, which binds calcium and reduces the risk of calcium oxalate stones. At the same time, the higher urine pH causes calcium and phosphate to become more likely to form solid crystals, increasing the risk of calcium phosphate stones.

Supported mechanismbased on 1 study

What the research says

1 study

  1. Study: Malic Acid Supplementation Increases Urinary Citrate Excretion and Urinary pH: Implications for the Potential Treatment of Calcium Oxalate Stone Disease

    Taking malic acid for a week made urine less acidic and raised the risk of forming certain types of kidney stones made of calcium and phosphate, even though it didn't clearly lower the risk of other common stones. So yes, it shifts the type of stone risk.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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