Caffeine intake and the risk of kidney stones

Abstract

Background: Although caffeine intake may increase urine calcium excretion, caffeine-containing beverages have been associated with a lower risk of nephrolithiasis.

Objective: We sought to determine the association between caffeine intake and the risk of incident kidney stones in 3 large prospective cohorts.

Design: We prospectively analyzed the association between intake of caffeine and incidence of kidney stones in 3 large ongoing cohort studies, the Health Professionals Follow-Up Study (HPFS) and the Nurses' Health Studies (NHS) I and II. Information on the consumption of caffeine and the incidence of kidney stones was collected by validated questionnaires.

Results: The analysis included 217,883 participants; over a median follow-up of >8 y, 4982 incident cases occurred. After multivariate adjustment for age, BMI, fluid intake, and other factors, participants in the highest quintile of caffeine intake had a 26% (95% CI: 12%, 38%) lower risk of developing stones in the HPFS cohort, a 29% lower risk (95% CI: 15%, 41%) in the NHS I cohort, and a 31% lower risk (95% CI: 18%, 42%) in the NHS II cohort (P-trend < 0.001 for all cohorts). The association remained significant in the subgroup of participants with a low or no intake of caffeinated coffee in the HPFS cohort. Among 6033 participants with 24-h urine data, the intake of caffeine was associated with higher urine volume, calcium, and potassium and with lower urine oxalate and supersaturation for calcium oxalate and uric acid.

Conclusion: Caffeine intake is independently associated with a lower risk of incident kidney stones.

Keywords: caffeine; coffee; kidney stones; nutrition; prospective study.

FIGURE 1

Restricted cubic splines of caffeine intake and the risk of kidney stones: Health Professionals Follow-Up Study. The model is adjusted for age, BMI, use of thiazides, use of calcium supplements, and intakes of calcium, phosphate, sodium, potassium, magnesium, fructose, oxalate, phytate, total fluid, alcohol, and vitamins B-6, C, and D. The gray-shaded area represents 95% CIs. The lower plot represents the distribution of caffeine intake. P < 0.001 for linearity, P = 0.85 for nonlinearity.

FIGURE 2

Restricted cubic splines of caffeine intake and the risk of kidney stones: Nurses’ Health Study I. The model is adjusted for age, BMI, use of thiazides, use of calcium supplements, and intakes of calcium, phosphate, sodium, potassium, magnesium, fructose, oxalate, phytate, total fluid, alcohol, and vitamins B-6, C, and D. The gray-shaded area represents 95% CIs. The lower plot represents the distribution of caffeine intake. P < 0.001 for linearity, P = 0.004 for nonlinearity.

FIGURE 3

Restricted cubic splines of caffeine intake and the risk of kidney stones: Nurses’ Health Study II. The model is adjusted for age, BMI, use of thiazides, use of calcium supplements, and intakes of calcium, phosphate, sodium, potassium, magnesium, fructose, oxalate, phytate, total fluid, alcohol, and vitamins B-6, C, and D. The gray-shaded area represents 95% CIs. The lower plot represents the distribution of caffeine intake. P < 0.001 for linearity, P = 0.20 for nonlinearity.