Adherence to the Mediterranean Dietary Pattern and Incidence of Nephrolithiasis in the Seguimiento Universidad de Navarra Follow-up (SUN) Cohort.

Background: Diet plays an important role in the pathogenesis of nephrolithiasis. Limited data are available to investigate the association between a Mediterranean dietary pattern and risk for nephrolithiasis.

Study Design: Prospective cohort study.

Setting & Participants: 16,094 men and women without a history of nephrolithiasis who participated in the Seguimiento Universidad de Navarra Follow-up (SUN) Project.

Predictors: A validated 136-item food frequency questionnaire was used to assess baseline adherence to a Mediterranean dietary pattern that is high in fruits, vegetables, nuts, fish, and legumes, but moderate in alcohol and low in meats, saturated fats, and sugars. A Mediterranean dietary pattern score was calculated and categorized into 3 groups (0-3, 4-6, and 7-9 points). Additional factors included in statistical models were sex, age, body mass index, smoking, physical activity, time spent watching television, following a medical nutritional therapy, water and energy intake, calcium and vitamin D supplementation, and history of hypertension or diabetes.

Outcomes: Incidence of nephrolithiasis. Participants were classified as having incident nephrolithiasis if they reported a physician-made diagnosis of nephrolithiasis during follow-up.

Results: After a mean follow-up of 9.6 years, 735 new cases of nephrolithiasis were identified. The multivariable HRs of nephrolithiasis for the 2 highest categories of adherence to the Mediterranean dietary pattern, using the lowest category as the reference, were 0.93 (95% CI, 0.79-1.09) and 0.64 (95% CI, 0.48-0.87); P for trend=0.01. The risk for nephrolithiasis was lower with greater consumption of dairy products and vegetables and greater with higher monounsaturated fatty acid to saturated fatty acid ratio.

Limitations: No information for kidney stone composition.

Conclusions: Greater adherence to a Mediterranean dietary pattern was associated with reduced risk for incident nephrolithiasis. Additional longitudinal studies are needed.