How do we separate proven findings from marketing hype?
Stone research is a model of mechanistic clarity: the outcome (recurrence) is binary, the chemistry (24-hour urine) is measurable, and the five classical randomized trials built a prevention framework the supplement aisle endlessly imitates and rarely matches. This chapter reads the trials, the paradoxes (calcium, tea, vitamin C megadoses), and the one herb whose reputation runs ahead of its evidence.
A field built on measurable chemistry teaches measurable reading:
Stone disease is ancient — lithotomy (cutting for the stone) appears in Hippocratic texts, and 'cutting for stone' was surgery itself for two millennia.
Extracorporeal shock wave lithotripsy — focused shockwaves shattering stones from outside the body — replaces open surgery for most stones. The stone century pivots.
The first randomized trial of fluid intake in recurrent formers: urine volume >2 L halved recurrence over five years — prevention's foundational evidence.
Borghi again: normal calcium + low sodium/protein beats the low-calcium diet — 'avoid dairy' retires as stone advice, discredited by recurrence data.
Guidelines consolidate around metabolic evaluation for recurrent formers — stone prevention becomes personal chemistry, measured then treated.
Oxalate-degrading gut bacteria (Oxalobacter), genetic risk scores, and precision dietary targeting — the field's next chapter, building on the five old trials' foundation.
POPULATION · 199 first-time calcium stone formers, 5 years
FINDING · Randomized to high water intake (urine >2 L/day) versus no treatment: recurrence fell from 27.0% to 12.1% — plain water, half the stones.
LIMITATION · Unblinded by nature; first-timers rather than heavy recurrers — but the effect size and duration made fluid the field's first-line evidence.
POPULATION · 120 men with recurrent calcium oxalate stones and hypercalciuria, 5 years
FINDING · Normal dietary calcium with reduced sodium and animal protein HALVED recurrence versus the low-calcium diet (the paradox proven: 12.1% vs 27.9% events).
LIMITATION · Men only, modest size — but the direction was decisive and mechanistically explained (gut oxalate binding); 'avoid calcium' stone advice has been wrong since this trial.
POPULATION · Recurrent calcium stone formers with hypocitraturia, ~3 years
FINDING · Potassium citrate therapy reduced new stone formation versus control — citrate repletion in citrate-deficient formers works.
LIMITATION · Small sample by modern standards; the effect concentrates in the hypocitraturic subgroup it targets — the personalization lesson in prescription form.
POPULATION · 36,282 postmenopausal women in the Women's Health Initiative CaD trial
FINDING · Randomized calcium + vitamin D supplementation was associated with a ~17% higher kidney-stone risk — the unpaired-supplement side of the calcium paradox.
LIMITATION · Secondary outcome, supplement-plus-food pattern not fully separated — but combined with Borghi's dietary trial, the timing story is coherent and guideline-accepted.
POPULATION · Health Professionals and Nurses' Health Study cohorts, hundreds of thousands of person-years
FINDING · Dietary patterns mapped: higher fluid and dietary calcium protective; high sodium, animal protein, and fructose associated with higher risk — the epidemiologic spine of the dietary protocol.
LIMITATION · Observational; self-reported diet; the randomized trials (Borghi) carried the causal confirmation — the cohorts drew the map the trials verified.
POPULATION · Recurrent calcium stone formers with elevated urinary calcium across multiple trials
FINDING · Thiazide diuretics reduced urinary calcium and stone recurrence versus control — the prescription tier for hypercalciuria, with the known gout-chemistry trade-off our gout page teaches.
LIMITATION · Dose and duration varied; the uric-acid-raising effect is the drug's known cost — one medication, two chemistries, the physician's balancing act.