RESUMO
The Dietary Approaches to Stop Hypertension (DASH) diet is highly effective in controlling blood pressure (BP). Although Na restriction is not a primary focus within the DASH diet, it is recommended that it be added to control BP. Therefore, we aimed to systematically review the characteristics and BP-lowering effects of Na-restricted DASH diet interventions. We searched thirteen databases, namely, MEDLINE, Embase, Cochrane Central Register of Controlled Trials, KoreaMed, KISS, KMbase, RISS, CINAHL, Scopus, ClinicalTrials.gov, Grey Literature Report, OpenGrey and PQDT Global, for articles published through May 2023. The randomised controlled trials assessing the BP-lowering effect of the Na-restricted DASH diet in adults aged 18 years and older were included. The study protocol was registered in the PROSPERO registry (CRD42023409996). The risk of bias in the included studies was also assessed. Nine articles were included in this review. Interventions were categorised into three types: feeding, provision and education, and the study results were compared by intervention type. BP was significantly reduced in two of the three feeding studies, one of the three provisional studies and none of the educational studies. In eight studies, effect sizes varied among both systolic BP (-7·7 to -2·4) and diastolic BP (-8·3 to 0·1). Six studies showed an overall high risk of bias. In conclusion, Na-restricted DASH may have beneficial effects on BP control. Additionally, compared with control interventions, feeding interventions appeared to have a greater BP-lowering effect. Further high-quality studies are needed to improve the quality of the evidence.