Nutrient intake and use of beverages and the risk of kidney stones among male smokers.

High intakes of calcium, potassium, and fluids have been shown to be associated with lowered risk of kidney stones. The authors studied the associations between diet and risk of kidney stones in a cohort of 27,001 Finnish male smokers aged 50-69 years who were initially free of kidney stones. All men participated in the Alpha-Tocopherol, Beta-Carotene Lung Cancer Prevention Study and completed a validated dietary questionnaire at baseline. After 5 years of follow-up (1985-1988), 329 men had been diagnosed with kidney stones. After data were controlled for possible confounders, the relative risk of kidney stones for men in the highest quartile of magnesium intake was 0.52 (95% confidence interval (CI) 0.32-0.85) as compared with men in the lowest quartile. Intake of fiber was directly associated with risk (relative risk (RR) = 2.06, 95% CI 1.39-3.03). Calcium intake was not associated with the risk of kidney stones. Beer consumption was inversely associated with risk of kidney stones; each bottle of beer consumed per day was estimated to reduce risk by 40% (RR = 0.60, 95% CI 0.47-0.76). In conclusion, the authors observed that magnesium intake and beer consumption were inversely associated and fiber intake was directly associated with risk of kidney stones.