Plasma Trimethylamine <i>N</i>‐Oxide Levels in Nondialysis Chronic Kidney Disease Patients Following Meal Challenge

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/m², glomerular filtration rate, 32.5 [18.5] mL/min) consumed lunches containing codfish, red meat, and chickpeas, within a 7-day interval between meals. TMAO plasma levels were assessed using the HPLC-EM/EM method before and after the 4-h meal challenge. Patients presented TMAO plasma levels of 9.06 µM. Consumption of codfish significantly increases the TMAO levels (to 23.5 µM, p < 0.001) compared to red meat and chickpeas. We conclude that codfish, compared to red meat and vegetable meal, provoked a transient elevation in TMAO levels in patients with CKD. Therefore, this result suggests that it is prudent to prescribe fish with low TMAO content for these patients. The response to ingesting TMAO-rich foods in CKD patients needs more study.