Menni C, et al. - Researchers determined the correlation between carotid-femoral pulse wave velocity (PWV), a measure of arterial stiffness, and gut microbiome composition in middle-aged women from the TwinsUK cohort with concurrent serum metabolomics data. An inverse relation of gut microbiome diversity to arterial stiffness was found in women. Seven operational taxonomic units were found to be related to PWV after adjusting for covariates and multiple testing—two belonging to the Ruminococcaceae family. Metabolic syndrome was shown to have only minimal mediating impact on the influence of gut microbiome composition on PWV. This is the first human observation linking the gut microbiome to arterial stiffness. Data indicated that targeting the microbiome may be a way to treat arterial ageing.