Associations between dietary macronutrient composition and kidney stone prevalence in the U.S. adult population

The relationship between macronutrient intake and kidney stone formation remains unclear, with previous studies yielding inconsistent findings due to their focus on single nutrients. A more integrated dietary assessment may provide a clearer understanding of dietary contributions to lithogenic risk. To investigate the associations between the energy distribution of dietary macronutrients (protein, carbohydrate, and fat) and the prevalence of kidney stones among U.S. adults. This cross-sectional study included 24,235 adults from the National Health and Nutrition Examination Survey (NHANES) 2007–2018. Macronutrient intake was assessed as a percentage of total energy based on 24-hour dietary recall data. kidney stone prevalence was determined via self-reported history. Multivariable logistic regression models and restricted cubic spline analyses were used to evaluate the nonlinear relationships between macronutrient energy proportions and kidney stone prevalence, adjusting for relevant demographic and clinical covariates. A significant U-shaped association was observed between protein intake and kidney stone prevalence, with the lowest prevalence at approximately 23% of total energy. Carbohydrate intake showed a similar U-shaped pattern, with the lowest prevalence at 40–50% of energy. Fat intake demonstrated a reverse L-shaped association; the prevalence remained stable when fat comprised 40% was associated with a higher odds (OR: 1.12; 95% CI: 1.01–1.26). Our findings indicate that both insufficient and excessive macronutrient intake are associated with higher kidney stone prevalence. A balanced macronutrient profile—with moderate proportions of protein, carbohydrate, and fat—may be beneficial for kidney stone prevention and could help inform dietary recommendations. Prospective studies are warranted to confirm these associations and clarify underlying mechanisms.