Formation of calcium oxalate kidney stones is related to consumption of some ultra-processed foods: a case-control study.

BACKGROUND AND

OBJECTIVES

The global increase in kidney stones might be attributable to dietary factors. Western diets high in ultra-processed foods (UPFs) are raising health concerns. While UPFs are linked to health risks, their connection to kidney stone formation is not well understood. This research attempted to investigate the relationship between UPFs and calcium oxalate kidney stones.

SUBJECTS AND

METHODS

This case-control study was conducted in Tehran among 366 participants (183 incident cases with confirmed calcium oxalate stones and 183 age- and sex-matched controls). Demographic characteristics, anthropometric indices, medical history, physical activity, and dietary intake were recorded via interviews. Dietary intake was assessed using a validated 147-item food frequency questionnaire (FFQ), and food items were categorized based on the NOVA classification system. Relationships between UPF consumption and kidney stones were examined using multivariable logistic regression, adjusting for potential confounders (e.g., total energy intake, BMI, and lifestyle factors).

RESULTS

Confounding factor adjustment (Model 2) showed that the highest tertile of sweets and confectionery intake was associated with higher odds of calcium oxalate kidney stones compared with the lowest tertile (OR: 2.11, 95% CI: 1.15-3.90, P-trend = 0.017). Furthermore, kidney stones were less common in persons in the highest tertile of dairy product intake than in the lowest tertile (OR: 0.54, 95% CI: 0.29-0.97, P-trend = 0.036). However, total UPF intake did not show a significant relationship with the odds of calcium oxalate kidney stones (OR: 0.73, 95% CI: 0.39-1.30, P-trend = 0.289).

CONCLUSIONS

The study findings suggest an association between specific sub-groups of UPFs, particularly sweets, and an increased likelihood of calcium oxalate kidney stone occurrence, while higher dairy intake may have a protective association, albeit with caution due to potential recall bias. These findings should be interpreted as associative rather than causal. Further prospective studies are warranted to confirm these observations.