Recent reports have implicated carnitine, a chemical naturally found in red meat, can increase the risk of heart disease, not because of its direct effects but after processing by bacteria in your intestines. 

Every human has close to 2 lbs of bacteria in their digestive system and more individual bacterial cells than human cells by more than 10 to 1.

But a new study published in the New England Journal of Medicine adds more weight to the fact that byproducts of consuming certain foods and having hut bacteria process them may lead to heart disease.

The current study looked at lecithin, a fat found in egg yolks, red meats, liver, soy, wheat, peanuts and milk.  When you eat these and other foods that contain lecithin it is broken up in the body into another chemical, choline.  Bacteria in the human digestive tract consume the choline and then create a chemical called TMAO (trimethylamine N-oxide). This research builds upon reserch produced by Dr. Stanley Hazen from the Cleveland Clinic who also found the link between carnitine and heart disease. 

TMAO is known to increase heart disease and hardening of the arteries, also called arteriosclerosis which is a known indicator of heart attacks and strokes to come.

To test the role of lecithin researchers had study volunteers eat two hard boiled eggs and looked at the levels of TMAO in their bloodstream.  But if the participants were given a strong antibiotic, which would eliminate certain gut bacteria, their TMAO levels never rose.  If people were taken off of antibiotics then their blood levels of TMAO increased to normal levels after eating eggs.  This strongly implicated bacteria in the production of TMAO.

To directly link TMAO levels to heart attack directly, instead of just implicating possible risk, researchers followed over 4,000 people who had undergone angiography.  Blood levels of TMAO were taken and patients were followed for three years.

What the researchers found was that those with high TMAO levels were more than two times as likely to have heart attack, stroke or die compared to those with low levels of TMAO.  

Although TMAO is known to be a factor in predicting heart disease related illness, it is not known how it acts and whether it works in concert with cholesterol levels to make people sick.

We have a complex relationship with the trillions of bacteria that we share a body with.  We provide them a home and they give us nutrients and protect us against invasive bacteria such as C. diff and Salmonella.  

Further analysis of populations to determine if certain gut bacteria makeups predispose people to heart disease would be the next course of action. With this research progressing at a fast pace it is foreseeable that scientists may find a specific bacterial species or strain that causes the production of TMAO and might be able to selectively kill it or vaccinate against it.