(P16-008-25) Examining the Relationship Between Health Literacy, Nutrition Literacy, and Food Literacy and Diet Behaviors in Adults: A Systematic Review

Objectives: To examine the association between Health Literacy (HL), Nutrition Literacy (NL), and Food Literacy (FL) – collectively referred to as Diet Related Literacy (DRL) – and diet behaviors in adults.

Methods: A systematic search was conducted using Covidence to capture relevant literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) systematic review guidelines, following pre-registration in PROSPERO (ID CRD42024556816). Data extraction and study quality assessment (using an adapted 10-item version of the Downs and Black scale; scores from 0 to 10) were subsequently implemented.

Results: A total of 49 studies were identified from 2,425 screened, with publication dates from 2009 to 2023, and most taking place in North America, Europe, or Asia. Diet behaviors examined included intake of specific foods (n=26) and adherence to specific diet patterns (e.g., Mediterranean Diet; n=23). Various tools were used to examine DRL types, with some being used interchangeably. Across 49 studies, 34 positive (i.e., better diet behaviors with higher DRL) and 38 non-significant/negative relationships were identified. Positive findings were more frequent in studies using a comprehensive framework to measure DRL – specifically, combining functional (basic complexity), interactive (intermediate complexity), and critical (highest complexity) levels of literacy. Only 33% (n=3) of studies measuring just functional literacy found positive relationships, compared to 65% (n=13) positive findings in studies using all three literacy levels. Study quality averaged 7.1, with common issues in response rates, tool validity, and sample size.

Conclusions: The association between DRL and diet behaviors remains mixed. Clarity is hindered by inconsistent DRL definitions and tool use (e.g., conflating HL and NL). Tools measuring only functional literacy—the most basic level—showed limited effectiveness, with only one-third reporting positive associations with diet behaviors. Not all health literacy tools are equal; while simple to administer, these tools may lack the theoretical complexity to detect the full scope of literacy. Transparency in reporting response rates, sample sizes, and tool adaptations is essential for reproducibility and informing effective nutrition interventions.

Funding Sources: NICHD 2T32HD087137-06