Dietary Calcium from
Dairy and Non-dairy Sources, and Risk of Symptomatic Kidney Stones
Purpose
Because of high correlations between dairy intake and total
dietary calcium, previously reported associations between lower calcium intake
and increased kidney stone risk represent de facto associations between milk
products and risk. We examined associations between dietary calcium from
nondairy and dairy sources, and symptomatic nephrolithiasis.
Materials and Methods
We performed prospective studies in the Health Professionals
Follow-up Study (HPFS) in 30,762 men, and in the Nurses' Health Study (NHS) I and
II in 94,164 and 101,701 women, respectively. We excluded men 60 years old or
older because we previously reported inverse associations between calcium
intake and risk only in men younger than 60 years. Food frequency
questionnaires were used to assess calcium intake every 4 years. We used Cox
proportional hazards regression to adjust for age, body mass index,
supplemental calcium, diet and other factors.
Results
We documented 5,270 incident kidney stones during the
combined 56 years of followup. In participants in the highest vs the lowest
quintile of nondairy dietary calcium the multivariate relative risk of kidney
stones was 0.71 (95% CI 0.56–0.92, p for trend 0.007) in HPFS, 0.82 (95% CI
0.69–0.98, p trend 0.08) in NHS I and 0.74 (95% CI 0.63–0.87, p trend 0.002) in
NHS II. When comparing the highest to the lowest quintile of dairy calcium, the
multivariate relative risk was 0.77 (95% CI 0.63–0.95, p trend 0.01) for HPFS,
0.83 (95% CI 0.69–0.99, p trend 0.05) for NHS I and 0.76 (95% CI 0.65–0.88, p trend
0.001) for NHS II.
Conclusions
Higher dietary calcium from nondairy or dairy sources is
independently associated with a lower kidney stone risk.
Russel's Note Vitamin D supplementation also decreased
urinary calcium excretion as well as stone growth, suggesting that it may help
prevent the risk of stone formation.
Dietary Calcium from
Dairy and Non-dairy Sources, and Risk of Symptomatic Kidney Stones The Journal
of Urology, October 2013Volume 190, Issue 4, Pages 1255–1259
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