BACKGROUND: The association of protein from different food sources and different plasma amino acids with risk of chronic kidney disease (CKD) is unclear. OBJECTIVES: We aimed to investigate longitudinal relationships of dietary protein intake from different sources, and quantity of plasma amino acids with new-onset CKD in the general population. METHODS: Participants (mean age: 56 years) without CKD at baseline were included from the UK Biobank. 176,980 were included in the analysis for protein intakes and 99,061 participants were included in the analysis for plasma amino acids. Information on dietary protein was collected based on a 24-hour dietary recall from the previous day. Plasma amino acids concentrations were measured by a high-throughput NMR-based metabolic biomarker profiling platform. The study outcome was new-onset CKD. RESULTS: During a median follow-up of 12 years (begin between 2006 and 2010, end at 2021), 3,542 participants (2,128,626 person-year) developed new-onset CKD. Higher intakes of dairy-derived and fish-derived protein were associated with lower incidence of CKD (per standard deviation, SD increment, adjusted hazard ratio, HR [95% confidence interval, 95%CI]= 0.95 [0.91-0.98] and 0.95 [0.92,0.99], respectively), but protein intake from other foods was not (P for trend >
0.1). Moreover, incident CKD was lower among those with higher plasma histidine (per SD increment
adjusted HR =0.90
95% CI: 0.86-0.95), tyrosine (0.90
0.87-0.94), isoleucine (0.89
0.85-0.92), leucine (0.89
0.85-0.93), and valine (0.89
0.85-0.93). CONCLUSION: The protein intake from dairy and fish, as well as the concentration of plasma histidine, tyrosine, isoleucine, leucine and valine were inversely associated with new-onset CKD.