Red meat, L-carnitine and atherosclerosis

In the current year (2013), at 7 April one article showed up in Nature magazine, introducing results from studies telling us that L-carnitine found in red meat has atherosclerosis potential (link). Conversion of this aminoacid to the atherosclerotic substance (which is trimethylamien N-oxide - TMAO) occur in participate of gut microflora. Authors of the research concluded, that eating of red meat may increase the risk of development cardiovascular disease because of increasing size of plaque. So, in that view, We should avert red meat in our diet.

Going further, we find out, that conversion of L-carnitine to TMAO occur  in presence of pathogenic bacteria, the Enterobacteriaceae, family of Gram-negative bacteria such as Salmonella, Shigella, Klebsiella, Citrobacter. Therefore, it's not about red meat, but bacteria which makes L-carnitine harmful. It's well known our diet influence gut microflora, what was pointed out by Chris Woolston, whos answer for the published data we could read same day in the Nature News & Comment, in article titled "red mead + wrong bacteria = bad news for hearts".

It is worth to mention Staffan Lindeberg comment here:

"This study supports the old notion that Western diets negatively affect the gut flora with all sorts of problematic substances entering our body. However, meat is probably not the main issue here, in particular not whole meat as opposed to processed meat. Apparently, healthy non-Western diets can be rich in 'red' game meat (in addition to fruits, vegetables, root vegetables etc.) and still improve the gut flora. Furthermore, L-carnitine has been shown to prevent atherosclerotic disease in other animal models with indirect evidence in humans too. The mouse model in the present study (the apoE knockout mouse) is a rather peculiar genetically modified species which may not be relevant for human atherosclerosis. So there are many uncertainties around this mechanistic study.

The systematic review that the authors cite (Micha R et al 2010) concludes the following: "Consumption of processed meats, but not red meats, is associated with higher incidence of CHD and diabetes mellitus.""

Less than a week later, at 13 April showed up a review article, which indicates about positive influence of L-carnitine on circulatory system. This review included 13 controlled trials in 3,629 patients. Supplementation of L-carnitine aminoacid was associated with 27% reduction in all-cause mortality, 65% reduction in ventricular arrhytmias and 40% reduction in the development of angina, and, also reduction in infarct size. All mentioned changes were significant or highly sighnificant. Supplementation of this aminoacid with the purpose of improve circulatory system work seems to be meaningful. Moreover, without statistical significance, there was seen also a reduction in myocardial reinfarctions and heart failure in a review mentioned above. Authors has suggested some potential mechanism for observed results: improving cellular respiratory (beta-oxidation), prevent from lipotoxicity and ischemia, and by replenishing concetration of L-carnitine in falling muscle heart, and as DiNicolantonio says: during ischemia and myocardial infarction.

Similar results were pointed out about eggs. In this product, TMAO is converted from choline, as Chriss Kresser wrote in article titled "Red meat and eggs on trial again, but jury is still out". There's many another data suggesting about good influence of eggs of circulatory sytem. They are a very good source of heart protective constituents, such as vitamin C, B12, B9 and lipophilic, antioxidant vitamin E. In 2012 at Ancestral Health Symposium, Mat Lalonde presented his own model of nutrient density (link), where results about eggs are follow: eggs are very rich source of nutrients, especially yolk. If you throw it away, because of cholesterol content, you waste much more.

The conclusion is we shouldn't put away red meat or eggs away. In fact, the processed meat is harmful to us, but red meat always played a very important role in our diet and evolution. It's worth to pay attention to our gut flora. Processed food and cereal grains surely won't help you to improve your microbiom.