U‐Shaped Association Between Dietary Copper Intake and New‐Onset Chronic Kidney Disease: A 30‐Year Follow‐Up Study From Young Adulthood to Midlife

The relationship of dietary copper intake with new-onset chronic kidney disease (CKD) remained unclear. We aimed to examine the association of dietary copper intake with new-onset CKD in a 30-year follow-up study from young adulthood to midlife. A total of 4038 U.S. adults aged 18-30 years and without reduced estimated glomerular filtration rate (eGFR) from the Coronary Artery Risk Development in Young Adults (CARDIA) study was included. During a 30-year follow-up, 642 (15.9%) participants developed new-onset CKD. Overall, there was a U-shaped relationship between dietary copper intake and new-onset CKD (p for nonlinearity = 0.034). When copper intake was assessed as quartiles, compared with those in the second quartile (2.03-<2.46 mg/day), the adjusted hazard ratios (HRs) (95% confidence interval [CI]) for new-onset CKD were 1.29 (1.05, 1.66), 1.29 (1.02, 1.64), and 1.49 (1.16, 1.91) for participants in the first (<2.03 mg/day), third (2.46-<3.11 mg/day), and fourth (≥3.11 mg/day) quartiles, respectively. Similar U-shaped associations were observed for new-onset eGFR decline and albuminuria. There was a U-shaped relationship of dietary total copper intake with new-onset CKD, with the lowest risk at a dietary copper intake of 2.03-<2.46 mg/day. Emphasizing the importance of maintaining optimal copper intake levels for the primary prevention of CKD.