INFLUENCE OF DIFFERENT DIETS ON URINE COMPOSITION AND THE RISK OF CALCIUM-OXALATE STONE FORMATION

The aim of this 17-day study was to examine the influence of four diff erent diets on urine composition and the risk of calcium oxalate stone formation in 10 healthy male subjects. In the course of phase 0, the subjects were on their individual diet for 2 days. In the following ph ases I, II, and III the subjects received three different standard die ts for a duration of 5 days each. Whereas DIET 1 (normal mixed diet) c orresponded to the dietary habits of men aged 19 to 35 years, DIET 2 ( balanced mixed diet) and DIET 3 (ovo-lacto-vegetarian diet) were calcu lated according to the dietary recommendations of the German Society o f Nutrition (DGE) for the same age-group. The risk of calcium oxalate stone formation, calculated by the computer program EQUIL of FINLAYSON , was highest on the self-selected diet and on DIET 1, but declined si gnificantly on the intake of DIET 2 by 50 % on average compared to DIE T 1 and by 61 % compared to phase 0. On DIET 3 no further significant decline in the risk of calcium oxalate stone formation was observed. T herefore, it can be concluded that the change of usual dietary habits into a balanced mixed diet significantly reduces the risk of calcium o xalate stone formation. With a vegetarian diet a compatable decline in urine supersaturation of calcium oxalate can be achieved with respect to a mixed diet according to requirements. Since urinary oxalic acid excretion increased significantly, a vegetarian diet is not recommend for calcium oxalate stone patients with absorptive hyperoxaluria.