*2.4. Data Extraction*

We independently abstracted data regarding study characteristics including the first author's name, publication year, the country in which the study took place, study design, study population details, comorbidities, DASH diet assessment tool, and the use of anti-hypertensive medication. As far as statistical data are concerned, we independently extracted risk estimates with their corresponding 95% confidence intervals (CI) regarding the risk of hypertension based on the level (high or low) of adherence to the DASH diet.

### *2.5. Risk of Bias in Individual Studies*

Two independent researchers assessed the risk of bias in the included observational studies using the Newcastle–Ottawa scale (NOS) and checklists for cross-sectional or cohort studies developed by the Joanna Briggs Institute (JBI). The JBI checklist for the cohort studies includes 11 items regarding the study design, while the checklist for the crosssectional studies comprises 8 questions. There are three available options to respond to these items, "yes" indicating high quality, "no" indicating poor quality, or "unclear".
