Does sugar cause kidney stones?

That it causes them has not been shown. In observational studies sugar, fructose and sugary drinks above all, is consistently linked to more stones. A 2013 systematic review of 28 randomized trials in people who had already had calcium stones found that cutting soft drinks lowered the risk of a repeat symptomatic stone, a risk ratio of 0.83 with an interval from 0.71 to 0.98, on low-strength evidence that rests on a single trial. In that trial, 34 percent of heavy soft drink drinkers told to cut back had renal colic, against 41 percent of those who carried on.

Unsettled. The only randomized evidence is about soft drinks, which in that trial were mostly cola, and no trial has tested sugar on its own against kidney stones. The rest comes from observational data and from short feeding studies of urine chemistry.

People who had renal colic, percent

One randomized trial, pooled in a 2009 meta-analysis of 8 trials with 1855 stone formers. The drinks were mostly cola, so the effect of sugar is not separated from the rest of the drink. Source: card ev-sgks-02 below.

What the trials found

Cutting soft drinks

Both reviews that pooled stone prevention trials found the same single soft drink trial. The 2009 meta-analysis of 8 trials in 1855 stone formers reported fewer attacks of renal colic in heavy soft drink drinkers assigned to drink less, 34 against 41 percent. The 2013 review of 28 trials put that as a risk ratio of 0.83 and rated the evidence low strength. The drinks were mostly cola with phosphoric acid, so neither review can say how much of the effect was sugar.

Sugar, soft drinks and kidney stones on a ratio scale

Randomized trialsObservational data

The top row is a risk ratio from randomized evidence. The other rows are odds ratios from cross-sectional surveys, which compare people who have had stones with those who have not and cannot show cause. Sources: cards ev-sgks-01, ev-sgks-08, ev-sgks-09 and ev-sgks-10 below.

Fructose rather than sugar in general

Three US cohorts of 241,538 nurses and health professionals recorded 4902 new kidney stones. In all three, people in the top fifth of total fructose intake had a significantly higher risk than those in the bottom fifth. Total fructose counts free fructose plus the fructose half of ordinary table sugar. Carbohydrates other than fructose were not linked to stones in any cohort. The abstract gives no size for the risk.

Larger syntheses agree on direction. A 2020 meta-analysis of 50 studies in 1,322,133 people listed fructose and soda among the main dietary risk factors for new stones, with no pooled figure for either in the abstract. A 2024 umbrella review of 17 meta-analyses rated fructose intake a suggestive risk factor, alongside belly fat, type 2 diabetes and salt. Suggestive is a middle grade of credibility for an association.

What surveys add

In a US survey of 21,590 adults, those in the top quarter of added sugar intake had odds of having had a stone 1.56 times those in the bottom quarter, an interval of 1.25 to 1.94, and the odds rose above about 63 g of added sugar a day. Sugar from dairy foods went the other way, an odds ratio of 0.67. In a second survey of 15,779 young and middle-aged adults, the top third of sugary drink intake had odds 1.664 times those of non-drinkers. These are snapshots. A stone could have come before the diet that was recorded.

What sugar does to urine

In 33 healthy men aged 40 to 65 who drank 200 g of fructose a day for 2 weeks, urine became more acidic, carried more oxalate and less magnesium, and blood uric acid rose. Those changes favor stones, and no stones were measured. The analysis compared the men before and after, with no group that went without fructose.

Who should be careful

Not for everyone. If you have had a kidney stone, soft drinks are the one sugar source with trial evidence behind cutting them, from heavy drinkers in a single trial. The large doses matter more than ordinary ones. In a meta-analysis of 21 feeding trials in 425 people, fructose swapped for other carbohydrate at the same calories did not raise blood uric acid, a difference of 0.56 umol/L with an interval from -6.62 to 7.74. Extra fructose at 213 to 219 g a day on top of the diet did raise it in people without diabetes.

Uric acid is a risk marker for one kind of stone and not a stone itself. We found no evidence specific to children, pregnancy or medicines for this question.

What expert bodies say

WHO recommends that adults and children keep free sugars below 10 percent of daily energy, a strong recommendation, and suggests below 5 percent. That limit was set for body weight and tooth decay rather than kidney stones. We found no statement from NIDDK, the American Urological Association or the European Association of Urology specifically on sugar and kidney stones.

How we searched

Searched: a local copy of PubMed on 7 October 2026, for sugar, sucrose, fructose, sugar-sweetened drinks, soda and added sugars with kidney stones, nephrolithiasis and urinary calcium (41 hits, all read by title), for sugar and fructose with uric acid, oxalate and urinary calcium in reviews (13 hits), and for soft drinks with stone recurrence (3 hits). Our local copy of ClinicalTrials.gov had nothing registered, and Retraction Watch listed none of the included papers. Web searches found no newer synthesis.

Included: a systematic review and a meta-analysis of stone prevention trials, a meta-analysis of fructose feeding trials, a meta-analysis and an umbrella review of observational studies, three US cohorts, two US national surveys, a fructose feeding study of urine chemistry and the WHO sugars guideline.

Excluded: a 2013 cohort paper on soft drinks that is not in our local copy of PubMed, so its quotations could not be checked against the abstract, though its findings agree with the cohorts above. Also a narrative review of supplements, a review of urinary citrate, a diet soda study in six people, a review of uric acid in blood only, a reanalysis without stone outcomes, an online survey and an intravenous fructose study.

What we read: abstracts, and the relevant section of the WHO guideline.

What we could not get: the pooled figures for fructose and soda in the 2020 meta-analysis, which are not in its abstract, and the sizes of risk in the three US cohorts.

What would change this answer

A randomized trial in people with recurrent stones that replaces sugary drinks with water and counts repeat stones. We found none under way.
A trial that separates sugar from the rest of a soft drink, so that cola acid and sugar stop being tested as one thing.
Published risk sizes for fructose from the large cohorts and the 2020 meta-analysis.

More on sugar itself is on the sugar page.

The food behind this question

Sugar: the two WHO numbers are not one rule — numbers, evidence and safety

The same question for other foods (kidney stones)

Sources

ev-sgks-01 · Meta-analysis or systematic review · systematic review of randomized controlled trials (AHRQ) · n = 28 trials
Low-strength evidence showed that reducing soft-drink consumption decreased recurrent symptomatic stone risk (RR, 0.83 [CI, 0.71 to 0.98]).
Who: adults with past calcium kidney stones in RCTs of recurrence prevention
Effect: reduced soft-drink consumption: recurrent symptomatic stone RR 0.83 (95% CI 0.71 to 0.98); strength of evidence low
Certainty: The estimate rests on one RCT of soda reduction (Shuster 1992); the soda there is mostly cola with phosphoric acid, so the effect of sugar is not separated out.
Ann Intern Med, 2013 · checked 2026-10-07 · we read the abstract
ev-sgks-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized trials · n = 1855
In one trial, fewer high soft drink consumers assigned to reduced soft drink intake had renal colic than controls (34% vs 41%, p=0.023).
Who: adults with a history of nephrolithiasis in 8 diet, fluid or supplement trials with at least 3 months follow-up; one trial in high soft drink consumers
Effect: renal colic 34% with reduced soft drink intake vs 41% in controls (p = 0.023)
Certainty: The effect is only in those who drank a lot of soda; study quality is mixed. No RCT tested an independent effect of sugar.
Eur Urol, 2009 · checked 2026-10-07 · we read the abstract
ev-sgks-03 · Meta-analysis or systematic review · systematic review and meta-analysis of controlled feeding trials · n = 425
Isocaloric exchange of fructose for other carbohydrate did not affect serum uric acid in diabetic and nondiabetic participants [MD = 0.56 μmol/L (95% CI: -6.62, 7.74)], with no evidence of inter-study heterogeneity.
Who: people with and without diabetes in controlled feeding trials of at least 7 days
Effect: isocaloric fructose: serum uric acid MD 0.56 umol/L (95% CI -6.62 to 7.74); hypercaloric fructose at 213-219 g/day: significant increase in non-diabetic participants
Certainty: Uric acid is a marker of urate stone risk, not the stones themselves. In the abstract the unit for the hypercaloric MD "mmol/L" appears to be a typo (should be μmol/L), so the figure was not put in the claim.
J Nutr, 2012 · checked 2026-10-07 · we read the abstract
ev-sgks-04 · Observational data · systematic review and meta-analysis of observational studies and RCTs · n = 1,322,133
Prominent risk factors for incident stones were body mass index (1.39,1.27-1.52), dietary sodium (1.38, 1.21-1.56), fructose, meat, animal protein, and soda.
Who: adults in observational studies and RCTs of modifiable lifestyle factors and incident nephrolithiasis
Effect: fructose and soda identified as risk factors (pooled RR not given in the abstract); fluid intake protective RR 0.55 (95% CI 0.51 to 0.60)
Certainty: Numbers for fructose and soda are not given in the abstract; full text in PMC not checked.
BMC Nephrol, 2020 · checked 2026-10-07 · we read the abstract
ev-sgks-05 · Observational data · umbrella review of meta-analyses with AMSTAR 2 and GRADE · n = 17 meta-analyses
The authors' study demonstrates the suggestive causal (central obesity, type 2 diabetes, gout, dietary sodium, fructose intake and higher temperatures) risk factors of nephrolithiasis.
Who: 17 meta-analyses covering 46 risk factors for nephrolithiasis
Effect: fructose intake graded as a suggestive causal risk factor (GRADE-based credibility)
Certainty: Synthesis of observational meta-analyses; "suggestive" is a middle class of credibility of the association, not an established cause.
Int J Surg, 2024 · checked 2026-10-07 · we read the abstract
ev-sgks-06 · Observational data · three prospective cohort studies with repeated food frequency questionnaires · n = 241,538
The multivariate relative risks of kidney stones significantly increased for participants in the highest compared to the lowest quintile of total-fructose intake for all three study groups.
Who: Nurses' Health Study I (93,730 older women), II (101,824 younger women) and Health Professionals Follow-up Study (45,984 men)
Effect: significantly higher multivariate relative risk in the highest vs lowest quintile of total fructose in all three cohorts; 4902 incident stones
Certainty: RR sizes not given in the abstract. Total fructose = free fructose + half of sucrose, i.e., ordinary sugar is included.
Kidney Int, 2008 · checked 2026-10-07 · we read the abstract
ev-sgks-07 · Observational data · three prospective cohort studies · n = 241,538
Non-fructose carbohydrates were not associated with increased risk in any cohort.
Who: NHS I, NHS II and HPFS participants
Effect: non-fructose carbohydrate intake not associated with incident kidney stones in any cohort
Certainty: Observational data; glucose and starch are neutral in these cohorts.
Kidney Int, 2008 · checked 2026-10-07 · we read the abstract
ev-sgks-08 · Observational data · cross-sectional analysis of a national survey · n = 21,590
In the fully adjusted regression model, compared to those in quartile 1, the population in quartile 4 of total sugar intake showed a significant risk of nephrolithiasis [odds ratio (OR): 1.23; 95% confidence interval (CI): 1.00-1.51]; OR for added sugar intake was 1.56 (95% CI: 1.25-1.94).
Who: NHANES 2007-2018 participants
Effect: added sugar Q4 vs Q1 OR 1.56 (95% CI 1.25 to 1.94); total sugar Q4 OR 1.23 (1.00 to 1.51); risk rose above about 63 g/day added sugar
Certainty: Cross-sectional: the stone could have been there before the diet change; does not show causality.
J Nutr, 2023 · checked 2026-10-07 · we read the abstract
ev-sgks-09 · Observational data · cross-sectional analysis of a national survey · n = 21,590
Added sugar intake from meat, egg, and oil was significantly associated with risk of nephrolithiasis (quartile 4, OR: 1.22; 95% CI: 1.02-1.47), whereas total sugar intake from dairy products was in reverse (quartile 4, OR: 0.67; 95% CI: 0.54-0.82).
Who: NHANES 2007-2018 participants
Effect: total sugar from dairy products Q4 OR 0.67 (95% CI 0.54 to 0.82); sugar from beverages Q4 OR 1.36 (1.07 to 1.72)
Certainty: Probably an effect of dairy calcium, not lactose; what matters is which food the sugar comes from.
J Nutr, 2023 · checked 2026-10-07 · we read the abstract
ev-sgks-10 · Observational data · cross-sectional analysis of a national survey · n = 15,779
Compared to individuals who do not consume SSB, kidney stones risk increased with absolute SSB intake across ascending tertiles: the ORs were 1.231 (95% Cl: 0.995, 1.523), 1.335 (95% Cl: 1.075, 1.658), and 1.664 (95% Cl: 1.353, 2.048) for the lowest to highest tertiles, respectively.
Who: NHANES 2007-2016 participants, middle-aged and young adults
Effect: highest tertile of absolute SSB intake vs none OR 1.664 (95% CI 1.353 to 2.048); per 100 calories/day OR 1.065 (1.038 to 1.093)
Certainty: Cross-sectional; obesity and alcohol modified the association.
World J Urol, 2025 · checked 2026-10-07 · we read the abstract
ev-sgks-11 · Observational data · pre-post analysis of fructose feeding within a randomized trial (no fructose-free comparator in this analysis) · n = 33
Ingestion of fructose was associated with an increased serum level of uric acid (p < 0.001), a decrease in serum ionized calcium (p = 0.003) with a mild increase in PTH (p < 0.05) and a drop in urinary pH (p = 0.02), an increase in urine oxalate (p = 0.016) and decrease in urinary magnesium (p = 0.003).
Who: healthy men aged 40-65 drinking 2.1 quarts (2 L) of 10% fructose (200 g/day) for 2 weeks, analyzed from a previously published randomized study
Effect: serum uric acid up (p < 0.001), urinary pH down (p = 0.02), urine oxalate up (p = 0.016), urinary magnesium down (p = 0.003)
Certainty: The dose is very large (about 5 cans of fructose soda a day); stones were not measured, only urinary markers.
BMC Nephrol, 2018 · checked 2026-10-07 · we read the abstract
ev-sgks-12 · Position of an expert body · WHO guideline · n = —
In both adults and children, WHO recommends reducing the intake of free sugars to less than 10% of total energy intake2 (strong recommendation). WHO suggests a further reduction of the intake of free sugars to below 5% of total energy intake (conditional recommendation3).
Who: adults and children
Effect: free sugars <10% of energy (strong), <5% (conditional)
Certainty: The limit is derived from weight and caries, not from stones; no separate position of the body on sugar and stones was found.
WHO, 2015, Guideline: sugars intake for adults and children · checked 2026-10-07 · we read the section

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.