de Boer IH, Zelnick LR, Ruzinski J, et al. - Researchers conducted this randomized clinical trial with a 2 × 2 factorial design to ascertain if supplementation with vitamin D₃ or omega-3 fatty acids prevents chronic kidney disease (CKD) development or type 2 diabetes (T2D) progression. They randomized participants (n = 370) to receive vitamin D₃ (2000 IU/d) and omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid; 1 g/d), vitamin D₃ and placebo (n = 333), placebo and omega-3 fatty acids (n = 289), or 2 placebos (n = 320) for 5 years. A total of 934 participants completed the study. Among adults with T2D, vitamin D₃ or omega-3 fatty acid supplementation vs placebo did not result in a significant change in eGFR at 5 years. In T2D patients, the findings do not support the use of vitamin D or omega-3 fatty acid supplementation for preserving kidney function.