Trimethylamine N-oxide (TMAO) is a uremic toxin accumulated in patients with chronic kidney disease (CKD) and involved with atherosclerosis. TMAO is derived from the gut microbiota (nutrient fermentation) and is found in some fish and seafood. This pilot study evaluated the acute effects of cod fish, red meat, and vegetable meal consumption on plasma TMAO levels in nondialysis CKD patients. Patients (five women, three men, 72.5 [7.7] years, body mass index [BMI], 25.6 [1.4] kg/m