text_1: Higher plasma levels of I-carnitine, when associated with trimethylamine N-oxide, are negatively correlated with cardiovascular events in humans.
text_2: Chronic dietary L-carnitine supplementation in mice altered cecal microbial composition, markedly enhanced synthesis of TMA and TMAO, and increased atherosclerosis, but this did not occur if intestinal microbiota was concurrently suppressed.