Carnitine, a popular supplement taken by weight lifters and energy drink enthusiasts, has been shown to encourage gut microbes whose presence can lead to atherosclerosis.
This is also bad news for heavy meat eaters, such as Paleo Dieters, because carnitine is prevalent in red meat.
In a study published in Nature Medicine, Stanley Hazen and his fellow researchers at the Cleaveland Clinic Lerner Research Institute realized that mice that were fed diets rich in carnitine had a high prevalence of atherosclerosis, which is a thickening of the artery walls. However, when the same diet was fed to mice who were bred to have significantly less intestinal bacteria, there was no increase in heart disease.
This is because carnitine is an energy source for some bacteria, especially those that excrete substances that lead to an increase in bad cholesterol. This excess cholesterol results in a build up of plaque on the walls of the artery, which clogs the flow of blood to the heart.
This is impressive work that may help to explain the association seen in epidemiological studies between red meat consumption and coronary heart disease. —David Leake
Because carnitine helps fuel the mitochondria that power the cells in your body, many energy drinks have taken to including it, in a belief that it will supercharge the metabolism. There are however no good studies showing that it works as a metabolism booster. And since there is at least one good study showing links to heart disease, it might be wise to try something less deadly for that purpose. Like coffee.
However, the question for paleo dieters is more profound, since red meat is rich in carnitine.
Luckily for us, there is an excellent post on this subject from the author of the Perfect Health Diet, Paul Jaminet:
Jaminet’s point is that the bacteria that turn carnitine into dangerous substances in the body are in direct competition for resources with bacteria that feed on fiber from sources like potatoes and fruit. As long as your diet is balanced and contains sufficient sources of fiber, the balance of safe to unsafe bacteria in your body should normalize.