[www.nbcnews.com]

"Dr. Stanley Hazen of the Cleveland Clinic, who led the study, and his colleagues had accumulated evidence for a surprising new explanation of why red meat may contribute to heart disease. And they were testing it with this early morning experiment.

The researchers had come to believe that what damaged hearts was not just the thick edge of fat on steaks, or the delectable marbling of their tender interiors. In fact, these scientists suspected that saturated fat and cholesterol made only a minor contribution to the increased amount of heart disease seen in red-meat eaters. The real culprit, they proposed, was a little-studied chemical that is burped out by bacteria in the stomach after people eat red meat. It is quickly converted by the liver into yet another little-studied chemical called TMAO that gets into the blood and increases the risk of heart disease."

deeeper explanation of meat farts

[www.npr.org]

...

HAZEN: Well, what our studies show is that in our digestive tract, we have many, many bugs, microbes. They can digest carnitine; we can't. We get no calories from carnitine, but the bugs do. A byproduct that the microbes make gets released and converted in our bodies and then detected in the blood into a compound that actually helps promote clogging of the arteries or cholesterol deposition in the artery wall.

It does this by actually changing our metabolism of cholesterol. So this is not independent of cholesterol. It actually works through cholesterol. It changes how our body senses cholesterol and metabolizes cholesterol at the artery wall, in the liver and in the intestines.

LICHTMAN: So let me see if I get this - have this straight. So we eat red meat, it has carnitine it. Microbes in our body break it down, produce another compound, and that's TMAO, is that right?

HAZEN: That's TMA. That then is actually a gas, believe it or not, at body temperature. It smells like rotting fish, but we don't smell like rotting fish when we eat meat. That's because it goes straight to the liver through the portal circulation, and there's a cluster of enzymes in the liver that get rid of that compound and turn it into something called TMAO.

And that compound is the one that actually tracks with cardiovascular risk and promotes atherosclerosis both in animal studies we've - were able to show that if you feed animals carnitine, they got accelerated atherosclerosis, and they did so in a TMAO-dependent fashion. If you gave them antibiotics to suppress their intestinal flora, they no longer made the TMAO, they no longer got accelerate atherosclerosis.

If you give the downstream metabolite, TMAO, you get accelerated atherosclerosis. And then in humans, we went ahead and measured this metabolite of the carnitine, TMAO, and were able to show that blood levels of this metabolite very strongly predict future risks for heart attack, stroke and death.

...

And we then subsequently analyzed the microbes in the feces, in the stool, and could show that the composition of the microbes in the - from the gut in the omnivore were very different from what we found in the vegetarian or vegan, and the types of microbes that actually were involved in breaking down carnitine were not found as much in the vegetarian or vegan and were abundant in the omnivore.

...

HAZEN: It is. So carnitine is found in many things. It's - so carnitine comes from the same root word as carnivore. So carnis means flesh. So carnitine was discovered over 100 years ago, and the chemists who discovered it called it carnitine because it was found in animal products, things made of flesh.

And if you look at multiple different types of meat products, you find that the red ones - so beef, lamb, mutton, venison - these have higher levels, even duck and certain types of fish that have red, fleshy meat. They have higher levels of carnitine.

...

LICHTMAN: It's amazing to me that you can change the bacteria that live in your gut just by what you eat. I mean, it makes sense, but if you think of it as an ecosystem in there, but it's surprising.

HAZEN: Well, that's exactly what it is, an ecosystem. It's a closed terrarium, if you will, and there's - and there's only so much food. And so if you change the composition of what you're eating, the types of microbes that like what you're eating with proliferate more so than the types that don't. And there's only so much space and oh so much nutrient available.


And now the joke:

[www.amazon.com]

Panchito,

Supplemental L-carnitine is not processed by the alimentary system the way carnitine from animal products is. Dr. Greger mentions this in his latest appearance at the Veg Society of Hawai'i lectures. It's at about the 49-minute mark near the end of the video(the whole video is good, btw): [www.youtube.com]