Table 1.

The PICOS criteria used to construct the systematic review.

Criteria	Description
Participants	Adults aged ≥18 years, including those with the hypertensive condition. Animal studies and individuals with other specific diseases were excluded
Intervention/Exposure	Health literacy
Comparison	High vs low health literacy in relation to the outcomes (blood pressure and dietary salt intake) either by mean scores, quartiles, or cut-off values such as limited, adequate, marginal, and excellent health literacy
Outcomes	Dietary salt intake and blood pressure using validated measurements and protocol
Study Design	Randomised controlled trial (RCT), non-RCT, cohort, and cross-sectional studies