The dietary habits of idiopathic calcium stone-formers and normal control subjects

Objectives To examine the relationship between 12 macro- and micro-nutrient s and the risk of recurrent calcium stone formation by comparing the diets of a large outpatient clinic-based group of patients who had fanned calcium -based urinary tract calculi with that of a population-based control group matched for age, gender and body mass index. Patients, subjects and methods The dietary intake of 500 patients (cases) r andomly selected from the adult population attending an outpatient renal-st one clinic and being evaluated and/or treated for biochemically or radiolog ically diagnosed calcium-based upper urinary tract calculi were compared wi th those of 500 control subjects selected to march for age, sex and body ma ss index from a stratified probability sample of 2212 adults (not instituti onalized) living in the same geographical area. Results Comparing the mean nutritional intakes showed a statistically highe r consumption of energy, carbohydrates, sodium, fibre, vitamin C, fat and f olic acid among cases than in controls. The intake of calcium, alcohol and vitamin A was significantly higher among the controls. There were no signif icant differences in the intake of protein, niacin or iron. The results of these comparisons varied when the groups were stratified by sex, age and bo dy mass index. Conclusions Dietary risk factors for calcium-based urinary tract calculi ar e many and complex, and a detailed consideration of sex, age and body mass index is important in interpreting such data. While it is difficult to draw firm. conclusions about causes and effects of individual nutrients from th e available data, this study indicates a possibly more important role for d ietary fat in stone formation than has been previously recognized. This rel ationship needs to be further explored in relation to urinary risk. Factors , as it may be possible to advise patients to reduce dietary fat as a proph ylactic measure for stone formation. As dietary fat has been associated wit h cardiovascular diseases and possibly cancer, an overall recommendation to these patients for a low dietary fat intake may be easier to follow.