Eating Red Meat and Animal Foods Raise Heart Disease Risk: The Role of TMAO

 BACKGROUND

In 2011 reports from the Cleveland Clinic appeared that eating foods rich in L-carnitine (meats and duck) and choline (egg yolk) raise the levels of TMAO and cause atherosclerosis in animal models. Vegans tend to have much lower blood levels of TMAO by avoiding animal sourced foods (ASF). There are now hundreds of studies relating blood TMAO levels from diet choices to a variety of disease beyond just the heart, most notably diabetes and kidney disease. New data here points to more support for a diet (meat and eggs)-gut- heart connection. A sizeable % of all heart disease cases are due to elevated TMAO from dietary choices. 

INTRODUCTION

Effects of animal source foods (ASF) on atherosclerotic cardiovascular disease (ASCVD) and underlying mechanisms remain controversial. Researchers investigated prospective associations of different ASF with incident ASCVD and potential mediation by gut microbiota-generated trimethylamine N-oxide (TMAO) and traditional ASCVD risk pathways.

METHODS

 Among 3931 participants from a community-based US cohort aged 65+ years, ASF intakes and TMAO and metabolites were measured serially over time. Incident ASCVD (myocardial infarction, fatal coronary heart disease, stroke, other atherosclerotic death) was adjudicated over 12.5 years of follow-up. 

RESULTS

Higher intakes of unprocessed red meat, total meat, and total ASF associated with higher ASCVD risk. TMAO and metabolites together significantly mediated these associations and accounted for about 10.6% of the heart events.

Processed meat intake associated with a nonsignificant trend toward higher ASCVD. Among other risk pathways, blood glucose, insulin, and C-reactive protein, but not blood pressure or blood cholesterol, each significantly mediated the total meat-ASCVD association.

CONCLUSIONS

In this large, community-based cohort, higher meat intake associated with incident ASCVD, partly mediated by  L-carnitine abundant in red meat resulting in elevated TMAO.

These novel findings support biochemical links between dietary meat, gut microbiome pathways, and ASCVD.