Nutrition and urinary calcium stone formation in northwestern India: a case control study

The nutrient intake of 69 stone formers (SFs) from three subsets of the local population (urban 22, rural tribal 22 and rural nontribal 25) and 69 age, sex, weight and socioeconomically matched control subjects (NSs) (urban 20, rural tribal 22 and rural nontribal 27) was studied. Simultaneously their timed 24-h urine samples collected over a similar period were analyzed. In general caloric and protein intake was low in all the groups but was strikingly low in the rural subjects. Intake of all nutrients was lowest in the tribal group. Although no difference was observed in diet between NSs and SFs in the same population subjects, SFs had higher urinary excretion of oxalic acid and calcium and lower excretion of citric acid and excreted more saturated urine. Notably magnesium intake was normal in both NSs and SFs, but mean excretion of magnesium was lower than normal in all the groups, suggesting its defective absorption. The influence of dietary intake of protein, carbohydrate, fat, fiber, calcium and oxalic acid on urinary excretion of calcium, oxalic acid, uric acid, inorganic phosphorus, magnesium and citric acid was examined using the chi-square test. No association was observed, thus suggesting that this low nutrient intake did not influence the lithogenic process. Thus, the overall observations suggest: (a) poor nutrition, (b) no effect of diet on urinary stone disease, (c) no difference in the nutrient intake between NSs and SFs and (d) a higher excretion of promoters and a lower excretion of inhibitors in SFs than in NSs.