DOES CARNITINE FROM RED MEAT CONTRIBUTE TO HEART DISEASE THROUGH INTESTINAL BACTERIAL METABOLISM TO TMAO? By Chris Masterjohn The Bottom Line The bottom line here is that the popular interpretation of this study as an indictment of red meat makes no sense. Even if physiological levels of TMAO contribute to heart disease in humans (which is a big “if” at this point) and even if red meat were to raise TMAO substantially more than most other foods (which appears to be false), it wouldn’t in any way whatsoever follow that eating red meat causes heart disease. The biological effects of a food cannot possibly be reduced to one of the biological effects of one of the food’s components. Believing such a thing would require believing not only that the particular component has no other relevant biological effects, but that there are no relevant biological effects of any of the other tens of thousands of components of that food. As Chris Kresser pointed out today, the balance of epidemiological evidence fails to show an association between fresh, unprocessed red meat and heart disease. Numerous studies, including randomized trials, have suggested that carnitine supplementation improves outcomes in patients with cardiovascular disease. Carnitine thus may be a generally heart-protective nutrient. The authors acknowledge these studies in their discussion but suggest that carnitine may have conflicting effects, especially when used orally rather than intravenously as in some studies, since the oral route allows exposure to intestinal bacteria. If the carnitine in red meat were promoting atherosclerosis through its conversion to TMAO, however, then red meat should be no more dangerous than potatoes and carrots and the real killer should be seafood. How likely is this to be true? Prospective studies correlate fish consumption with a reduced risk of heart disease mortality. Some Pacific Island groups that eat seafood regularly, such as the Kitavans, appear to be free of heart disease. Randomized trials have tended to focus on fish oils rather than whole fish. Those testing advice to eat more fish are ambivalent, but they don’t seem to suggest that eating whole fish increases the risk of heart disease. The elucidation of nutritional pathways and biochemistry in this paper is interesting, but it shouldn’t serve as a reason to avoid red meat.
Posted on: Fri, 27 Jun 2014 20:19:00 +0000
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