Folate intake and incident chronic kidney disease: a 30-year follow-up study from young adulthood to midlife

Abstract

Background: The relation of long-term dietary folate intake with incident chronic kidney disease (CKD) remains uncertain. Objectives: We aimed to investigate the association between dietary folate intake and incident CKD in a 30-y follow-up study from young adulthood to midlife. Methods: A total of 4038 American adults aged 18–30 y and without reduced estimated glomerular filtration rate (eGFR) were enrolled in 1985–1986 and monitored until 2015–2016 in the CARDIA (Coronary Artery Risk Development in Young Adults) study. Diet was assessed by a validated dietary history questionnaire at baseline, in 1992–1993, and in 2005–2006. The primary outcome was incident CKD, defined as an eGFR <60 mL · min−1 · 1.73 m−2 or a urinary albumin to creatinine ratio (ACR) ≥30 mg/g. The secondary outcomes included 1) incident decreased eGFR, defined as an eGFR <60 mL · min−1 · 1.73 m−2, and 2) incident albuminuria, defined as an ACR ≥30 mg/g. Results: During the follow-up, 642 (15.9%) participants developed CKD. Overall, there was a significant L-shaped relation of dietary folate with incident CKD after adjustment for potential confounders. Compared with the lowest quintile of total folate intake, the multivariable-adjusted HRs (95% CIs) in quintiles 2–5 for incident CKD were 0.69 (0.56, 0.85), 0.35 (0.27, 0.45), 0.34 (0.26, 0.45), and 0.39 (0.30, 0.51), respectively. Similar results were found for the secondary outcomes. Moreover, the L-shaped association was confirmed in a subset of the cohort (n = 1462) with serum folate measured at baseline, in 1992, and in 2000. Conclusions: Higher folate intake in young adulthood was longitudinally associated with a lower incidence of CKD later in life. Additional studies are warranted to establish the causal inference.