Why is beef bad for your heart and arteries? Only your GI bacteria know for sure

Prior posts have noted the extent to which the makeup of the bacteria in one's GI tract can be critically important. The wrong mix, which apparently arises from the nature of one's diet, can lead to a wide variety of unfortunately ugly diseases and adverse conditions. Research now indicates that the makeup of one's GI "flora" explains a lot about why meat poses a potential risk of heart disease and atherosclerosis.

Previous research has shown that high levels of meat-eating are linked to cardiovascular risk, partly because of the saturated fats and cholesterol in meat. However, the higher levels of these ingredients is not sufficient to explain the difference in heart disease between meat eaters and vegans or vegetarians. The study demonstrates that differences in the bacterial colony of one's GI tract explains why.

The study followed 2,595 people and measured carnitine levels, as well as those of its byproduct, TMAO. Omnivores produced more TMAO than vegetarians and vegans after eating carnitine, the researchers found. Although carnitine is also found in fish, poultry, wheat, and some vegetables, its main food source is red meat, especially lamb, according to the study. Because vegetarians and vegans eat fewer foods that contain it, their gut bacteria does not process carnitine as easily, which may explain some of the health benefits of meatless diets.

The researchers also feed mice diets that would produce high levels of TMAO; this aspect of the study showed that the animals had higher levels of hardened arteries. However, if the researchers suppressed the bacteria living in the mouse's guts, the effects dissipated.

Carnitine is also an ingredient in many dietary supplements which are taken to increase muscle mass. The authors have noted that the safety of such supplements needs to be studied in light of the results from their work.

The study can be found at: http://www.nature.com/nm/journal/vaop/ncurrent/full/nm.3145.html