Effects of the mediterranean diet versus low-fat diet on metabolic syndrome outcomes: A systematic review and meta-analysis of randomized controlled trials

Several clinical studies have attributed the Mediterranean diet (MedDiet) to desirable metabolic health outcomes, but literature is saturated with studies conducted in Mediterranean regions questioning the diets applicability in non-Mediterranean countries. This review aimed to determine the effectiveness of MedDiet compared to a low-fat diet (LF-Diet) on metabolic components in those with or at risk of developing Metabolic Syndrome (MetS) in non-Mediterranean countries. We searched Medline, Embase and Global Health for randomized controlled trials published until October 2022 and a clinical trial register for ongoing studies. We identified 13 published trials (n = 1921) and 2 ongoing trials that met inclusion criteria. Random effects meta-analysis, yielded a statistically significant reduction in total cholesterol (MD -7.97, 95%CI -14.82 to −1.11) and systolic blood pressure (MD -2.04 mg/dl, 95%CI -3.68 to −0.39). Small non-significant pooled mean difference (MD) was observed for seven other MetS risk factors (body weight, waist circumference, diastolic blood pressure, blood glucose, triglycerides, LDL and HDL-cholesterol). Further inquiry is required to enhance certainty in estimates before health care providers can make an informed decision about possible dietary changes in MetS management and comorbidity prevention. •Metabolic syndrome and associated comorbidities place a major economic burden on worldwide health care systems.•This review and meta-analysis of 13 RCTs assessed the effectiveness of the Mediterranean diet versus a conventional low-fat diet on metabolic outcomes amongst high-risk populations in non-Mediterranean countries.•The Mediterranean diet was only significantly superior to the low-fat diet in reducing total cholesterol and systolic blood pressure.•Results from the MEDAS 14-item questionnaire show adherence to the Mediterranean Diet is greater than the low-fat diet in non-Mediterranean countries.