Trimethylamine N-Oxide Plasma Levels Following Red Meat and Cod Fish Intake: A Pilot Crossover Trial in Hemodialysis Patients

Abstract

Scope: The uremic toxin trimethylamine N-oxide (TMAO) accumulates in patients with chronic kidney disease (CKD) and is associated with its progression, cardiovascular disease, and other complications. The gut microbiota produces TMAO from substrates mainly found in red meat, eggs, and dairy. However, some saltwater fish also contain high levels of TMAO. Although fish consumption is generally linked to beneficial effects, its effects on CKD patients require further research. Methods and results: This study compares the effect of red meat and cod fish intake on TMAO plasma levels in CKD patients undergoing hemodialysis (HD). Participants received a single animal protein source (red meat vs. cod fish) for lunch and dinner for four consecutive days (each intervention), with a 2-week washout period in between. TMAO plasma levels were analyzed using LC-MS/MS. All 14 patients concluded the red meat intervention, while one refused to participate in the fish intervention. No significant difference in TMAO plasma levels was found post-red meat (p = 0.21) or fish intervention (p = 0.91), as well as between groups (p = 0.43). Conclusion: In this study, 4 days of red meat and cod fish intake did not significantly impact TMAO levels in HD patients, while other factors may be associated with their circulating levels.