Changing trends in the American diet and the rising prevalence of kidney stones

Abstract

Objective: To evaluate the trends in the American diet over the last 40 years (1974-2010), during which time the National Health and Nutrition Examination Survey data set has documented an increase in stone prevalence from 3.8% to 8.8%.

Materials and methods: We used the National Health and Nutrition Examination Survey reported rates for stone disease (1974-2010) to compare the United States Department of Agriculture's food distribution data during the same period. Three data points for prevalence were used from the literature. We correlated these to changing lithogenic food distributions using linear models to interpolate annual changes in prevalence. Spearman correlations were performed (P ≤.05) using SAS 9.2 (SAS Institute, Cary, NC).

Results: Increased total daily calories (rho, 0.96; P <.001), fat (rho, 0.79; P <.001), protein (rho, 0.85; P <.001), fruit (rho, 0.6; P = .01), and vegetables (rho, 0.73; P <.001) correlated strongly with increasing stone prevalence. Dark green vegetables, flour or cereal products, fish or shellfish, corn products (including high fructose corn syrup), and added sugars also showed strong correlations with stone prevalence. Citrus fruits were negatively correlated to stone disease (rho, -0.18; P = .31). Protein, fruits and vegetables, and added sugars actually decreased in proportion to daily caloric per capita increases.

Conclusion: Increases in caloric intake and several lithogenic foods correlate temporally with increasing stone prevalence. The nature of this relationship is difficult to determine from this data; although, clearly, American diets have changed over the last 4 decades.