Intestinal Microbes and Heart Disease

     The significance of the study I will discuss is not completely clear other than to show that the microbes in one's digestive tract can have quite an impact on health. It should be pointed out before I discuss this bit of reasearch that the Mayo Clinic reviewed 13 controlled trials involving 3, 629 patients and found that L-carnitine reduced all-cause mortality by 27%, reduced ventricular arrhythmias by 65%, reduced angina by 40% and reduced infarct size.
     A recent study found that feeding mice acetyl carnitine as 1.3% of the diet resulted in alteration of the bacteria in the digestive tract of the animals. These bacteria converted the L-carnitine into TMAO (trimethylamine-N-oxide). The L-carnitine was not a problem unless the bacteria were present. Diets high in red meat tend to produce increased populations of these bacteria compared to diets containing other meats or vegetarian diets. TMAO was shown to cause or accelerate the development of heart disease in mice. The researchers found little evidence that cholesterol was a causative factor in heart disease.
     Scientists are focusing increasing attention on what is called the microbiome, the population of bacteria which inhabit the digestive tract. It appears that these bacteria can create all kinds of health problems. Healthy bacterial populations in the digestive tract are promoted by fiber intake and by supplementing with acidophilus and other beneficial organisms. Vegetarians did not produce TMAO when they consumed red meat suggesting that it takes consistent consumption of red meat to promote the growth of the bacteria which contribute to TMAO accumulation in the body.
     This study suggests that cholesterol is not a primary reason why red meat intake increases the risk of heart disease. Heart disease may be more closely associated with bacterial populations in the digestive tract.
     Koeth, Robert A., et al., Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis, Nature Medicine, April 7, 2013; doi:10.1038/nm.3145
DiNicolantonio, James J., et al., L-Carnitine in the secondary prevention of cardiovascular disease systematic review and meta-analysis, Mayo Clinic Proceedings, June 2013; 88(6),  DOI: http://dx.doi.org/10.1016/j.mayocp.2013.02.007
http://www.elsevier.com/about/press-releases/research-and-journals/l-carnitine-significantly-improves-patient-outcomes-following-heart-attack