Association between dietary factors and renal stones in adults

Urolithiasis is the third urinary disease and evidence shows that its incidence has increased continually during the past decades. The relationship between urinary stones and diet is known to some extent, but there are controversies about it. The aim of this study was to determine the relationship between dietary habits, food intake patterns and urinary stone disease. This was a case-control study with 161 adult patients with urinary stone disease referred to Hasheminejad Urology Center, Tehran, Iran, and 254 healthy subjects matched for age and gender. All the subjects were interviewed using a questionnaire to obtain data on demographic characteristics, dietary habits, and food consumption frequency. Data were analyzed using SPSS version 14. The independent T-test, chi square and regression were used to examine the differences. Findings showed that male-to-female ratio was 1.98:1. The prevalence of renal stone was highest in men aged between 30 and 50 years and in women aged between 40 and 60 years. There were no differences in height and weight between the two groups, but BMI was significantly higher in the case group (p=0.007). A family history of renal stones was observed more frequently in the patients (59% compared to 31.9%; p<0.001). The mean intakes of food sources of several nutrients were lower in the patients than in the healthy subjects: calcium (p=0.048), phosphorus (p=0.001), potassium (p<0.0001), vitamin A (p<0.0001), vitamin D (p<0.0001), and vitamin C (p=0.004). Regression analysis confirmed the differences between the two groups as regards sources of vitamins A and D. The intakes of sources of magnesium and vitamin B6, as well as of foods rich in oxalate, were not significantly different between the 2 groups. Results suggest that there are associations between urinary stone formation and the dietary intakes of nutrients such as calcium, phosphorus, potassium, vitamin A, vitamin D, and vitamin C. Considering the challenges of treatment and the costs of this relatively common disease, dietary recommendations may be an easy and cost-effective way to reduce its burden.