Fig. 1

Flowchart of the two-sample MR-analysis process. A Three important hypotheses for gut microbiota of cardiovascular diseases by forward MR. These three paths represent these three different hypotheses. Relevance assumption: SNPs are associated with gut microbiota (the exposure). Independence assumption: SNPs were completely independent of any potential confounders affecting gut microbiota and cardiovascular diseases. Exclusivity assumption: SNPs affect metabolites only through gut microbiota (exposure) and not via any alternative causal pathways. B Three important hypotheses for cardiovascular diseases of gut microbiota by forward MR. These three paths represent these three different hypotheses. Relevance assumption: SNPs are associated with cardiovascular diseases (the exposure). Independence assumption: SNPs were completely independent of any potential confounders affecting gut microbiota and cardiovascular diseases. Exclusivity assumption: SNPs affect metabolites only through cardiovascular diseases (exposure) and not via any alternative causal pathways