Meaty artery plaques

Study discovers a component of meat is transformed into a very dangerous compound by gut bacteria

L-carnitine is a substance found mostly in red meat, smaller amounts are also in chicken meat, eggs and dairy, and even smaller amounts are found in beans and avocados. A pioneering study set out to investigate what happens to this substance when digested by either vegans or meat-eaters because the two diet groups have such different gut bacteria it was assumed likely to determine the end product.

When both groups were given L-carnitine supplement, the difference in its metabolism was astonishing. Both groups’ gut bacteria processed it into an intermediate substance but meat-eaters’ bacteria then continued to transform this into a compound called TMAO, whilst the vegan bacteria did not or produced only miniscule amounts. TMAO is a dangerous substance known for building artery plaques (along with cholesterol) and increasing the risk of thrombosis – an event in which blood supply to an organ or body part is blocked by a torn-off plaque.

This study is the first of its kind to demonstrate how the differences in our diets not only determine what gut bacteria live in our digestive system but also what these bacteria manufacture from the food we feed them. And once again, vegans come out on top!


Koeth RA etal., 2019. L-Carnitine in omnivorous diets induces an atherogenic gut microbial pathway in humans. Journal of Clinical Investigation. 129(1): 373-387.