Tarini Shankar Ghosh and Ana Maria Valdes evaluate the evidence for clinical effects of microbiome altering interventions on cardiometabolic traits ### Key messages Cardiometabolic diseases are one of the main causes of morbidity and mortality in western countries and are increasing in low and middle income countries.1 Dietary intake is one of the main determinants of cardiometabolic health1 and of microbiome composition.2 The gut microbiome is known to play an important part in the development of cardiometabolic diseases, including hypertension, diabetes, and obesity.2 This is thought to be linked with the ability of the gut microbiome to modulate inflammation, insulin sensitivity, and blood lipid levels, and is hypothesised to be mediated by specific microbially produced metabolites such as short chain fatty acids (SCFAs), secondary bile acids, phenylacetylglutamine, and trimethylamine-N-oxide.2 As well as their direct influence, gut microbes can also modulate the response of the hum