The effect of DASH diet on components of metabolic syndrome: a systematic review and meta-analysis of randomized controlled trials

Background Metabolic syndrome (MetS) has emerged as an increasingly significant global health issue. The Dietary Approaches to Stop Hypertension (DASH) diet is recommended for managing MetS. However, existing meta-analyses often focus on individual MetS components, without providing a comprehensive evaluation of the DASH diet’s effects on the full spectrum of MetS components. Therefore, we conducted a systematic review and meta-analysis of randomized controlled trials evaluating the effects of the DASH diet on various components of MetS. Methods We performed a comprehensive search of PubMed, Web of Science, Embase, and Cochrane Library databases, covering studies published until April 6, 2025. We included RCTs that evaluated the effects of the DASH diet on MetS components such as waist circumference (WC), blood pressure (BP), fasting blood glucose (FBG), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR). Sensitivity analyses were conducted to assess result stability, and funnel plots were used to assess publication bias, with Egger’s test applied for significance ( p 0.05). Additionally, we used the GRADE approach to assess the certainty of evidence. Results A total of 14 studies involving 1,062 participants were included. The meta-analysis showed that, compared with non-DASH diets, the DASH diet significantly reduced WC (MD = −2.33 cm, 95% CI: −3.10 to −1.57), systolic BP (MD = −5.52 mmHg, 95% CI: −6.83 to −4.21), diastolic BP (MD = −3.93 mmHg, 95% CI: −4.76 to −3.10), TG (MD = −16.57 mg/dL, 95% CI: −23.53 to −9.61), HDL-C (MD = 1.44 mg/dL, 95% CI: 0.20 to 2.68), and HOMA-IR levels (MD = −0.71, 95% CI: −1.10 to −0.31). However, no significant difference was observed in FBG (MD = −0.91 mg/dL, 95% CI: −4.51 to 2.68). The GRADE approach for assessing certainty of evidence indicated that, with the exception of FBG and HDL-C where the certainty of evidence was low, the overall certainty of evidence for the remaining outcome measures was rated as moderate quality. Conclusion The DASH diet appears to have a positive effect on components of MetS and can be considered an effective dietary intervention for MetS patients. Systematic review registration CRD420251060235.