Trimethylamine N-oxide and platelets aggregation: insufficient evidence for causal inference in thrombosis

Trimethylamine N-oxide (TMAO) is an amine oxide generated in the liver from nutrients such as choline, betaine, or carnitine via an intermediate gut-bacteria driven metabolite, trimethylamine (TMA). Recently, Zhu et al. conducted a 2-month open-, non-placebo controlled intervention in vegetarians and omnivores using 450 mg total choline/day (1). Zhu et al. reported a significant increase in plasma TMAO concentrations (from 2.5 to 36.4 M in omnivores and from 2.6 to 27.2 M in vegetarians).