LAUSR

BACKGROUND & AIMS Cardiometabolic diseases (CMD) have shared properties and causes. Insulin resistance is a risk factor and characteristic of CMD and has been suggested to be modulated by gut microbiota (GM) derived plasma metabolites. As diet is among the most important modulators of GM, we performed a systematic review of the literature to assess if CMD can be modulated via dietary interventions targeting GM. METHODS A systematic review of the literature for clinical studies was performed on Ovid Medline and Ovid. Studies were assessed for risk of bias and patterns of intervention effects. A meta-analysis with random effects models was used to evaluate the effect of dietary interventions on clinical outcomes. RESULTS Our search yielded in 4,444 unique articles from which 15 randomized controlled trials and six non-randomized clinical trials were included. Overall risk of bias was high in all studies. In general, most dietary interventions changed the GM composition but no consistent effect could be found. Results of the meta-analyses showed that only diastolic blood pressure is decreased across interventions compared to controls (mean difference [95%CI]: -3.63 mmHg [-7.09 to -0.17], I2 = 0%, P = .04), and that a high fiber diet was associated with reduced triglyceride levels (mean difference [95%CI]: -0.69 mmol/L [-1.36 to -0.02], I2 = 59%, P = .04]. Other CMD parameters were not affected. CONCLUSIONS Dietary interventions modulate GM composition, blood pressure and circulating triglycerides. However, current studies have a high methodological heterogeneity and risk of bias. Well-designed and controlled studies are thus necessary to better understand the complex interaction between diet, microbiome and CMD. PROSPERO CRD42020188405.