Intestinal microbiota metabolism of l -carnitine, a nutrient in red meat, promotes atherosclerosis

The long-noted association of red meat with an increased risk of cardiovascular disease may be due to ingestion of a specific compound found in red meat, l-carnitine. The ability of this compound to promote atherosclerosis in mice requires that it be further metabolized by the gut microbiota. In humans, omnivores but not vegans or vegetarians metabolize l-carnitine in this manner, a difference which may be explained by effects of diet on the presence of specific types of bacteria in the gut.