Eating foods high in choline and L-carnitine, your gut microbiome produce a chemical compound, called trimethylamine (TMA). In the liver, TMA is converted to trimethylene N-oxide (TMAO), a harmful agent. 

People with high blood levels of TMAO is shown to have higher risk of premature death. In addition, they have four-fold increased risk of all-cause death. 

When you eat meat, your gut microbiome produces a chemical, trimethylene N-oxide (TMAO), which may raise your risk of getting cardiovascular events, like stroke and heart attack.