TMI about TMAO

Research continues to show over and over again that plant-based diets lead to better health outcomes than diets with high amounts of animal-based foods. Long-term dietary patterns shape the gut microbiome, and short-term dietary interventions can actually lead to reproducible changes in the flora of the microbiome. So investigators have looked at the differences between the microbiomes of meat-eaters and vegetarians. While there are many purported reasons for the findings of better health outcomes for vegetarians,  one of them is thought to be related to a metabolite called TMAO (trimethylamine-N-oxide). Red meat is rich in precursors of TMAO, like L-carnitine and (phosphatidyl) choline. These are two “ingredients” used by gut microbes to make trimethylamine, which is then converted into the metabolite TMAO by our livers. TMAO has been shown to be associated with the development of atherosclerosis (plaque) and thromboses (blood clots) in animal and human research.

‍

TMAO actually predicts 5-year mortality, independent of traditional CV risk factors. How? In research involving mice, supplementation with either TMAO or its precursor choline led to more deleterious changes in the heart, including fibrosis/scar tissue development, enlargement of the heart and even weakening of the pump function of the heart. In patients with known heart failure, higher levels of TMAO were even associated with worsening symptom levels. And in patients actually hospitalized with “acute” heart failure, TMAO independently predicted in-hospital and 1-year mortality. 

‍

Importantly, in another research experiment using mice, lowering TMAO resulted in significantly improved cardiac function, suggesting that this metabolite really does play a significant role in heart health.

‍

So it should make sense that dietary patterns with infrequent or absent consumption of meat and which emphasize consumption of fiber (found in vegetables, fruits, whole grains, legumes, nuts, and seeds) are healthier in study after study. In fact, vegetarians and vegans have nearly undetectable TMAO levels. 

‍

The good news? TMAO decreases significantly within weeks of eliminating red meat from the diet. So while you may have spent your life eating the typical Standard American Diet, it’s never too late to make a change and take back control of your health. Start by substituting one or two vegetarian meals into your diet each week. Your gut will LMAO in response.

‍

References:

Mamic P et al. J Am Coll Cardiol. 2023 May, 81 (17) 1729–1739

Koeth R.A. et al. Nat Med . 2013;19:576-585.

Wang Z., et al. Eur Heart J . 2019;40:583-594.