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TGetting plenty of calcium from foods has been shown to lower the likelihood of kidney stones in those most at
risk.
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. Researchers sought to examine associations between dietary calcium from non-dairy and dairy sources and symptomatic
nephrolithiasis.
In a large new analysis, men and women who consumed the most dietary calcium from foods had about 20 percent lower risk of developing kidney stones than peers who consumed the least calcium: although most stones that form in the kidneys are made of calcium oxalate, people should not be afraid of consuming calcium in
foods.
Because most kidney stones are made of calcium oxalate, it might seem counterintuitive to consume more calcium and end up with less in your kidneys, but there is theory about why it works, Frassetto
said.
The real culprit is oxalate, not calcium. Oxalate is found in many foods including fruits, vegetables, nuts and chocolate, and calcium binds to it avidly.
The more calcium in the digestive tract, the more oxalate it can bind and take out of the body before the oxalate is absorbed into the bloodstream and ends up in the kidneys and bile
duct.
Researchers conducted prospective studies in the Health Professionals Follow-up Study (HPFS; N=30,762 men), the Nurses’ Health Study I (NHS I; N=94,164 women), and the Nurses’ Health Study II (NHS II; N=101,701
women). They excluded men = 60 years old because we previously reported inverse associations between calcium intake and risk only in men < 60. Food frequency questionnaires assessed calcium intake every four years. Researchers used Cox proportional hazards regression to adjust for age, BMI, supplemental calcium, diet, and other
factors.
Scientists
documented 5,270 incident kidney stones over a combined 56 years of follow-up. For participants in the highest compared to lowest quintile of non-dairy dietary calcium, the multivariable relative risks of kidney stones were 0.71 (95% CI 0.56-0.92; P for trend 0.007) for HPFS, 0.82 (0.69-0.98; P trend 0.08) for NHS I, and 0.74 (0.63-0.87; P trend 0.002) for NHS II. The multivariable relative risks comparing highest to lowest quintile of dairy calcium were 0.77 (0.63-0.95; P trend 0.01) for HPFS, 0.83 (0.69-0.99; P trend 0.05) for NHS I, and 0.76 (0.65-0.88; P trend 0.001) for NHS
II.
Higher dietary calcium from either non-dairy or dairy sources is independently associated with lower kidney stone
risk.
For more information
Dietary calcium from dairy and non-dairy sources and risk of symptomatic kidney stones
http://www.jurology.com/article/S0022-5347%2813%2903862-7/abstract
(MDN)
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