Vitamin D for Kidney Stones

Vitamin D is not a treatment for kidney stones: no trial has tested it for preventing or dissolving stones in people who form them, and large trials in general populations found no reduction in stones. The question that matters is whether it adds risk, and at usual doses trials haven't found that it does. In the ViDA trial, 5,110 adults given 100,000 IU of vitamin D3 a month or placebo reported about the same number of stones over a median 3.3 years (76 vs 82; HR 0.90, 95% CI 0.66 to 1.23) (Malihi 2019, ViDA). Pooled trials lasting 24 weeks or more found no rise in stones (RR 0.66, 95% CI 0.41 to 1.09) (Malihi 2016), and neither did trials of 2,800 IU a day or more for a year or longer (RR 1.26, 95% CI 0.35 to 4.58) (Malihi 2019, review).

The catch is urine calcium. The same pooled trials found more hypercalciuria, meaning high urine calcium (RR 1.64), and more hypercalcaemia, high blood calcium (RR 1.54) (Malihi 2016). Daily calcium (1,000 mg) plus vitamin D (400 IU) raised stones by 17% over 7 years in 36,282 postmenopausal women (HR 1.17, 95% CI 1.02 to 1.34), though the trial can't say which caused it (Jackson 2006). At toxic doses vitamin D raises blood calcium enough to cause stones (NIH ODS 2025), and the European urology guideline lists it among compounds that can cause stones (EAU Guidelines). In people who already form stones, small studies show urine calcium rising in some but not others (Leaf 2012; Johri 2017), so stone specialists advise a 24-hour urine test after starting vitamin D (Khusid 2020).

Most kidney stones contain calcium. Vitamin D, and especially its active form calcitriol, increases how much calcium the gut absorbs, and urine calcium tracks that absorption, so in theory more vitamin D means more calcium in urine (Letavernier 2018). The trials bear part of this out. In pooled trials of 24 weeks or more, hypercalciuria was 64% more likely with vitamin D (RR 1.64, 95% CI 1.06 to 2.53; 14 studies), and the effect wasn't changed by dose, baseline vitamin D or calcium co-supplementation (Malihi 2016).

Pooled trials found no dose effect, but in one trial that compared doses directly, hypercalciuria rose with dose. Over 3 years in 373 healthy adults aged 55-70, some also given calcium if their diet was low in it, hypercalciuria occurred in 17% on 400 IU a day, 22% on 4,000 IU and 31% on 10,000 IU (P = .01), though average urine calcium didn't differ between groups (Billington 2020). In postmenopausal women all taking 1,200 mg of calcium a day, 10,000 IU of vitamin D made the odds of hypercalciuria 3.6 times higher than 600 IU over a year (OR 3.6, 95% CI 1.39 to 9.3) (Aloia 2018).

Stones form when urine is supersaturated, meaning it holds more calcium salt than it can keep dissolved. In 62 recurrent calcium stone formers given 2,000 IU a day or 50,000 IU a week, urine calcium rose but calcium oxalate and calcium phosphate supersaturation didn't change (Sardari Masihi 2023). A 6-week trial of 1,000 IU daily vs 50,000 IU weekly in stone formers found no change in urine calcium or supersaturation (Ferroni 2017). In an uncontrolled study, though, calcium phosphate supersaturation did rise (Vitale 2021). Genetic studies disagree: one linked lifelong higher vitamin D levels to more stones (OR 1.47 per SD, 95% CI 1.22 to 1.77) (Jian 2022), another found no significant effect (OR 1.134, 95% CI 0.953 to 1.350) (Zhang 2024).

Some people do respond badly. Loss-of-function changes in both copies of the CYP24A1 gene stop the body breaking down active vitamin D, causing high calcitriol, hypercalciuria and stones (Nesterova 2013), and reviewers suggest this may explain why select stone formers recur on supplements (Schulster 2020; Letavernier 2018). Granulomatous diseases such as sarcoidosis also make excess calcitriol and raise urine calcium, and the European urology guideline lists vitamin D excess among the causes of high urine calcium with high blood calcium (EAU Guidelines). Urine markers can't show who will form a stone; only stone outcomes can, and those trials are few.

There is no stone-prevention dose of vitamin D. Adults need 600 IU a day, or 800 IU over age 70, and the adult upper limit is 4,000 IU a day from all sources. Food provides some: 3 ounces of cooked sockeye salmon has about 570 IU and a cup of fortified milk about 120 IU (NIH ODS 2025). The Food and Nutrition Board also advises avoiding blood 25(OH)D above about 50-60 ng/mL (NIH ODS 2025), and stone reviewers note that routine vitamin D screening appears unnecessary for most stone patients (Schulster 2020). 4,000 IU is a ceiling, not a target. Stone specialists, extrapolating from general-population trials that counted stones, saw no rise in stones up to that dose and advised 24-hour urine tests to catch hypercalciuria in stone formers who start vitamin D (Khusid 2020). But trials of 3,200-4,000 IU a day found more hypercalcaemia, falls and hospital admissions (Zittermann 2023), and intakes below the upper limit might still cause harm over time (NIH ODS 2025).

For stone formers who are deficient, the studied regimens include 1,000 IU daily or 50,000 IU weekly for 6 weeks (Ferroni 2017), 2,000 IU daily for 12 weeks or 50,000 IU weekly for 8 weeks (Sardari Masihi 2023) and ergocalciferol 50,000 IU weekly for 8 weeks (Leaf 2012). The weekly 50,000 IU regimens raised levels more, but they were short courses of 6-8 weeks, not ongoing doses. These studies compared 24-hour urine before and after the course (Leaf 2012; Ferroni 2017; Sardari Masihi 2023). Calcium matters as much as vitamin D: the European urology guideline advises a normal 1,000-1,200 mg of calcium a day from diet and no calcium supplements except in enteric hyperoxaluria, plus 2.5-3 litres of fluid and no more than 4-5 g of salt a day (EAU Guidelines).

The largest stone data come from ViDA, a double-blind trial in 5,110 adults in Auckland, New Zealand. Over a median 3.3 years of 100,000 IU of vitamin D3 a month, 76 people on vitamin D and 82 on placebo reported a first stone event (HR 0.90, 95% CI 0.66 to 1.23; P = 0.51), and hospital records showed 7 vs 11 admissions for urinary stones. No one in the vitamin D arm of the blood-test subsample developed hypercalcaemia (Malihi 2019, ViDA).

Meta-analyses agree. Across 48 trials of 24 weeks or more with 19,833 participants, the 9 that reported stones showed a nonsignificant trend to fewer stones with vitamin D (RR 0.66, 95% CI 0.41 to 1.09; P = 0.10), while hypercalcaemia (RR 1.54) and hypercalciuria (RR 1.64) rose (Malihi 2016). In trials of 2,800 IU a day or more for at least a year, stones did not rise significantly (RR 1.26, 95% CI 0.35 to 4.58; 5 studies, 1,336 participants) (Malihi 2019, review). In 22 trials of 3,200-4,000 IU a day for 6 months or more, stones and hypercalciuria didn't differ, but hypercalcaemia was more common (RR 2.21, about 4 extra cases per 1,000 people), and the authors found safety reporting often incomplete (Zittermann 2023).

In the Women's Health Initiative, 36,282 postmenopausal women aged 50-79 took 1,000 mg of calcium (as calcium carbonate) with 400 IU of vitamin D3 a day, or placebo, for an average of 7 years. Kidney stones rose 17% (HR 1.17, 95% CI 1.02 to 1.34) (Jackson 2006): 449 women in the supplement group reported a stone, against 381 on placebo, and the excess was similar across the demographic, dietary and other risk factors examined (Wallace 2011). Total intake in the trial was about 2,100 mg of calcium and 765 IU of vitamin D a day from food and supplements (NIH ODS 2025).

Because both were given together, the trial can't separate calcium from vitamin D. Stone specialists note that a meta-analysis which found more stones with vitamin D included trials where calcium wasn't given equally to both groups, and that analyses which kept calcium equal found no stone increase (Khusid 2020). With calcium in both arms, 10,000 IU of vitamin D a day made hypercalciuria much more common than 600 IU (Aloia 2018). In 34 stone formers given vitamin D with calcium, 23.5% developed new hypercalciuria, and over a median 39 months half of them formed stones, against 11.5% of the rest (P = 0.038) (Hesswani 2015).

Trials in stone formers are small and short, and measure urine rather than stones. Among 29 deficient stone formers given 50,000 IU of vitamin D2 a week for 8 weeks, 25(OH)D rose from 17 to 35 ng/mL but mean urine calcium didn't change (257 vs 255 mg/day; P = 0.91), though 11 people rose by 20 mg/day or more, alongside higher urine sodium. The authors concluded vitamin D shouldn't be withheld solely because of stones, but urine calcium should be monitored (Leaf 2012). In 21 patients randomised to 1,000 IU daily or 50,000 IU weekly for 6 weeks, urine calcium and supersaturation didn't change (Ferroni 2017). In 62 recurrent stone formers, urine calcium rose on both 2,000 IU daily and 50,000 IU weekly, without a change in supersaturation (Sardari Masihi 2023).

Uncontrolled studies show a subgroup whose urine calcium climbs. Of 456 idiopathic stone formers screened, 31% were deficient; after 20,000 IU a week for 4 months in 37 of them, the overall rise in urine calcium was not significant (p = 0.06), but 6 of 26 normocalciuric patients became hypercalciuric (Johri 2017). In 33 deficient calcium stone formers, hypercalciuria rose from 6 to 13 patients (p = 0.03) (Vitale 2021), and a retrospective records study of 26 patients found urine calcium rose, possibly from diet (Taheri 2019). A retrospective cohort of 353 stone formers in Riyadh found recurrence in 45.8% of those given vitamin D and 32.8% of those who weren't (adjusted OR 1.65, 95% CI 1.01 to 2.71), highest at 50,000 IU a week, but people prescribed vitamin D may have differed in other ways (Alzaben 2025).

In 193,551 health professionals and nurses followed for more than 3.3 million person-years, intakes of 1,000 IU a day or more weren't significantly linked to stones in men (HR 1.08, 95% CI 0.80 to 1.47) or older women (HR 0.99), with a suggestion of higher risk in younger women (HR 1.18, 95% CI 0.94 to 1.48); supplements alone gave similar results, and the authors couldn't rule out risk at higher doses (Ferraro 2017). In 444,343 UK Biobank participants followed 12.6 years, higher blood vitamin D wasn't linked to stones (HR 0.88, 95% CI 0.77 to 1.01), and in women over 60 it was linked to fewer (Gao 2024).

A second UK Biobank analysis found vitamin D supplement users had more hypercalcaemia (OR 1.46) but no more future stones (Sha 2024), and a smaller cohort found no link across 20-100 ng/mL, though it recorded only 13 stones (Nguyen 2014). A genetic study found that a tendency to form stones was linked to slightly lower vitamin D levels, rather than the reverse (Zhang 2024). These studies can't prove vitamin D is safe for everyone, and few participants took high doses.

No trial has randomised people with past stones to vitamin D or placebo and counted new stones. The stone-former trials ran 6-12 weeks and measured urine, and the large trials enrolled general populations rather than stone formers, recording stones as a secondary, largely self-reported, outcome (Malihi 2019, ViDA; Jackson 2006). In children, only a small uncontrolled study exists: 36 children with stones from idiopathic hypercalciuria took 400-800 IU a day for 24 months without a significant change in urine calcium or new stone growth (Milart 2020).

Trials of more than 5,000 people that counted stones found no reduction, so the 'no' verdict rests on moderate evidence; no trial has tested vitamin D in people who already form stones.

The stone-related risks at high intakes are high blood and urine calcium. Vitamin D toxicity causes marked hypercalcaemia and hypercalciuria; hypercalcaemia can bring nausea, vomiting, muscle weakness, neuropsychiatric symptoms, excessive thirst and urination, and kidney stones, and in extreme cases kidney failure. Toxicity almost always comes from excessive supplement doses, and the adult upper limit is 4,000 IU a day (1,000-3,000 IU for children under 9, by age) (NIH ODS 2025). Even 3,200-4,000 IU a day raised hypercalcaemia in a small share of people in trials (Zittermann 2023).

Some people are far more sensitive. CYP24A1 deficiency can cause hypercalcaemia and stones (Nesterova 2013), sarcoidosis and other granulomatous diseases raise calcitriol and urine calcium (EAU Guidelines), and primary hyperparathyroidism causes about 5% of calcium stones (EAU Guidelines). The European urology guideline lists vitamin D among compounds that can cause drug-induced stones and advises stone formers to avoid excessive vitamin supplements (EAU Guidelines). People with any of these, or with chronic kidney disease, should take vitamin D only under their specialist's care. Pregnancy needs 600 IU a day, with the same 4,000 IU upper limit (NIH ODS 2025).

Calcium and high-dose vitamin D together can raise urine and blood calcium. What to take with vitamin D explains which combinations to avoid.

The interaction that matters most for stone formers is with thiazide diuretics, which the European urology guideline recommends for high urine calcium (EAU Guidelines): thiazides cut calcium loss in urine, and adding vitamin D, which raises absorption, might cause hypercalcaemia, especially in older adults and people with kidney problems or hyperparathyroidism (NIH ODS 2025). Calcium supplements add to vitamin D's effect on urine calcium (Aloia 2018; Jackson 2006). Steroids such as prednisone reduce calcium absorption and impair vitamin D metabolism, orlistat reduces vitamin D absorption, and high vitamin D intakes might reduce the potency of atorvastatin, lovastatin and simvastatin (NIH ODS 2025).