DietarySodiumIntakeandHealthIndicators: ASystematicReviewofPublishedLiterature betweenJanuary2015andDecember2019

Abstract

As the science surroundingpopulation sodium reduction evolves, monitoring and evaluating new studies on intake and health can help increase ourunderstandingoftheassociatedbenefitsandrisks.Herewedescribeasystematicreviewofrecentstudiesonsodiumintakeandhealth,examine the risk of bias (ROB) of selected studies, and provide direction for future research. Seven online databases were searched monthly from January 2015toDecember2019.Weselectedhumanstudiesthatmetspecifiedpopulation,intervention,comparison,outcome,time,setting/studydesign (PICOTS) criteria and abstracted attributes related to the study population, design, intervention, exposure, and outcomes, and evaluated ROB for thesubsetofstudiesonsodiumintakeandcardiovasculardiseaserisksorindicators.Of41,601abstractsreviewed,231studieswereidentifiedthat metthePICOTScriteriaandROBwasassessedfor54studies.Onehundredandfifty-seven(68%)studieswereobservationaland161(70%)focused on the general population. Five types of sodium interventions and a variety of urinary and dietary measurement methods were used to establish and quantify sodium intake. Five observational studies used multiple 24-h urine collections to assess sodium intake. Evidence mainly focused on cardiovascular-relatedindicators(48%)butencompassedanassortmentofoutcomes.StudiesvariedinROBdomainsand87%ofstudiesevaluated were missing information on ≥1 domains. Two or more studies on each of 12 outcomes (e.g., cognition) not previously included in systematic reviews and 9 new studies at low ROB suggest the need for ongoing or updated systematic reviews of evidence on sodium intake and health. Summarizing evidence from assessments on sodium and health outcomes was limited by the various methods used to measure sodium intake and outcomes, as well as lack of details related to study design and conduct. In line with research recommendations identified by the National AcademiesofScience,futureresearchisneededtoidentifyandstandardizemethodsformeasuringsodiumintake