Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease.
Level 3 - non-randomized controlled study
Translational study combining an observational human clinical risk cohort with mechanistic animal models
PubMed 21475195 · doi:10.1038/nature09922
What was done
Unbiased plasma metabolomics was used to identify small molecules that predict cardiovascular disease (CVD) risk, with findings validated in an independent large clinical cohort. Mechanistic experiments were conducted in mice given dietary supplementation with phosphatidylcholine metabolites (choline, trimethylamine N-oxide [TMAO], or betaine). Additional experiments utilized germ-free mice, gut flora suppression, and hyperlipidaemic mice to evaluate macrophage scavenger receptor expression, foam cell formation, and the role of host flavin monooxygenases.
What was found
Three phosphatidylcholine metabolites—choline, TMAO, and betaine—predicted CVD risk in the human cohort (exact numerical risks and sample sizes were not reported in the abstract). In mice, dietary choline, TMAO, or betaine upregulated macrophage scavenger receptors, and choline or TMAO supplementation promoted atherosclerosis. Germ-free conditions or gut flora suppression prevented dietary-choline-induced TMAO production, macrophage cholesterol accumulation, foam cell formation, and atherosclerosis acceleration. Flavin monooxygenase variation segregated with atherosclerosis in hyperlipidaemic mice.
Why it matters
This work identifies a mechanistic pathway linking gut microbial metabolism of common dietary lipids to atherosclerosis and clinical cardiovascular risk, introducing TMAO as both a biomarker and potential therapeutic target.
Limits
The abstract does not report cohort size, participant characteristics, follow-up duration, or quantitative effect sizes for the human risk association. Causal acceleration of atherosclerosis was demonstrated in rodent models and cannot be assumed to function identically in human clinical outcomes.
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