The article cautiously says that this doesn't mean you should avoid red meat, but c'mon, you should totally avoid red meat.
Study Points to New Culprit in Heart Disease - NYTimes.com
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.
That, at least, was the theory. So the question that morning was: Would a burst of TMAO show up in peoples’ blood after they ate steak? And would the same thing happen to a vegan who had not had meat for at least a year and who consumed the same meal?
The answers were: yes, there was a TMAO burst in the five meat eaters and no, the vegan did not have it. And TMAO levels turned out to predict heart attack risk in humans, the researchers found. The researchers also found that TMAO actually caused heart disease in mice. Additional studies with 23 vegetarians and vegans and 51 meat eaters showed that meat eaters normally had more TMAO in their blood and that they, unlike those who spurned meat, readily made TMAO after swallowing pills with carnitine.
“It’s really a beautiful combination of mouse studies and human studies to tell a story I find quite plausible,” said Dr. Daniel J. Rader, a heart disease researcher at the University of Pennsylvania School of Medicine, who was not involved in the research.