Why We Were Wrong: L-Carnitine

Raw beef on cutting board

All this time, we physicians have warned you about the risks of eating too much red meat. We worried that the high saturated fat and cholesterol content was damaging to your heart; however, we got it wrong. Red meat is still linked to an increased risk of heart disease, but it’s not just from the fat. New research points to a substance found in red meat called L-carnitine. This new research suggests that L-carnitine, either from red meat or taken in supplement form, poses a threat to your heart. Prior to the latest research, we’ve promoted this supplement on this show. Researchers claimed that it could increase energy, speed up weight loss, and improve athletic performance. Some energy drinks add L-carnitine for this reason. Now, I’m saying DON’T take it!

Here’s how it works: After you ingest L-carnitine, it travels to your gut, and intestinal bacteria converts the L-carnitine into a substance called TMA, which then gets processed by the liver. The liver converts TMA into a compound that has been linked to plaque build-up in the arteries and heart disease. This conversion was most apparent in those who regularly ate red meat. Remarkably, vegans and vegetarians, even after consuming a large amount of carnitine, did not produce significant levels of TMA. It may be because they have different gut bacteria.

Red meat is one of the highest sources of L-carnitine, at about 56-162 mg per serving. L-carnitine can also be found in foods like pork, seafood, and chicken, but at much lower levels, between 3 and 7 mg per serving. Dairy, like ice cream, milk and cheese, has between 3 and 8 mg per serving. However, the main source of L-carnitine for many people is supplements – with some people taking up to 500-1000 mg per day. The more L-carnitine you get, the more TMA you may make, which can damage your blood vessels even faster.

Because the greatest source of L-carnitine in our diet comes from red meat, I think we should avoid it as much as possible. I don’t eat much red meat myself (I think lean chicken tastes better anyway); however, I know that’s not an option for everyone. If you must eat red meat, try to eat 4 ounces or less per week. For those carnivores who love their steak, here are three simple things everyone can do to create a healthy environment in their gut, which can lessen the impact of L-carnitine:

  • Build an alkaline environment in your gut by eating leafy greens or using lemon/lime on salads and in water. (Yes, lemons are alkaline. Even though it has citric acid, its overall nutrients are alkaline.)
  • Choose plant protein sources, like hemp seeds or black beans, which help to remove toxins because of high fiber content.
  • Take a probiotic. As mentioned before, regular meat eaters converted more L-carnitine into TMA than vegetarians or vegans. This suggests that the type of bacteria in your gut makes a difference.