A recent study published in the journal Nature compared the effect of eating sirloin on measured blood levels of TMAO (Trimethylamine N-oxide if you're curious), a compound produced by gut bacteria presumably in response to carnitine in the meat, and previously associated with an increased risk of heart disease. What is truly amazing to me about this study is that the sample size consisted of six - not sixteen, not sixty - meat-eaters and one (one!) vegan and the results of those seven blood tests have been generalized to health advice promoted in almost every major news outlet across the country! The study participants were not pre-screened for other dietary sources of carnitine, general dietary quality of meat consumed, or pre-existing gut flora health or illness.
Given the profound benefits of eating healthy grass-fed meat, and the notable absence of any cardiovascular disease markers in those hunter-gatherer populations who add large amounts of such meat, in the context of a well-balanced diet, I will not be changing my eating habits or dietary recommendations anytime soon. On the other hand, overdosing with energy drinks, rich in caffeine as well as carnitine, now seems like even less of a reasonable idea!