Some few dietary recommendations are pretty sturdy like don’t eat lead or trans fatty acids. But it is becoming apparent to everyone that most dietary recommendations seem to be shaky and shifting like don’t eat fats or carbs or proteins. One of the latest bugaboos are diets high in red meats that are blamed for elevated risks of heart disease and mortality. But that’s not consistently so according to other studies.
Now regarding red meat, researchers are honing in on another possible culprit – a dietary metabolite called trimethylamine N-oxide, or TMAO. TMAO is linked to red meat consumption but also to some kinds of fish. (1)
But it’s wrinkly. TMAO is not in the red meat. Instead red meat is rich in carnitine that is also found in lots of other foods besides red meats. Carnitine is turned into TMA by certain bacteria in the gut and then TMAO in one more step that happens by way of an enzyme in the liver. The final resulting TMAO floating in your blood seems to cause many problems but the mechanisms of injury are not yet understood. It could be that TMAO is not really the problem after all but just a marker of something else that is.
If TMAO turns out to be as bad as they say, besides avoiding red meats, we could combat it by capitalizing on this complicated pathway of production in your body. We could alter bugs in your intestine or block that liver enzyme and then keep eating whatever we want. Maybe some people don’t have those bacteria or are born without the liver enzyme.
With all these kinds of complications it’s no wonder dietary recommendations are such a mess.
1. Abbasi J TMAO and heart disease: The new red meat risk? JAMA June 11, 2019;321(22):2149-51.