Antioxidants and Self-Reported History of Kidney Stones: The National Health and Nutrition Examination Survey

Background and Purpose: Animal studies have demonstrated the likely role of oxidative tissue damage in the pathophysiology of stone disease; however, the effect of antioxidants on stone formation in the human population is unknown. We evaluated the association between serum antioxidant levels and the self-reported prevalence of kidney stones in a large cross-sectional population in a retrospective cohort study. Materials and Methods: Serum levels of antioxidants among adult participants in the National Health and Nutrition Examination Survey (NHANES III) 1988-1994 were compared between those with and without a self-reported history of kidney stones, adjusting for covariates of age, sex, body mass index (BMI), race/ethnicity, diabetes, and hypertension. Results: The prevalence of kidney stones was 5.25% (95% confidence interval: 4.60%, 5.90%). The prevalence of kidney stones was higher in males, white/non-Hispanics, diabetics, and those with hypertension. The prevalence of kidney stones increased with BMI. After adjusting for covariates, mean levels of alpha-carotene, betacarotene, and beta-cryptoxanthin were significantly lower in those with kidney stones (-9.36%, - 10.79%, and -8.48%, respectively). When analyzed by quartile, higher serum levels of beta-carotene and beta-cryptoxanthin,, trended toward a decreasing prevalence of stones (P = 0.007 and P = 0.03, respectively), indicating that the highest levels of these antioxidants may protect against the formation of kidney stones. Conclusions: Lower levels of alpha-carotene, beta-carotene, and beta-cryptoxanthin are associated with a history of kidney stones and may indicate a role for these antioxidants in preventing stone formation.