The relationship between health literacy, food literacy, and dietary choices-a systematic review.

Objectives: Health-promoting behaviors play a key role in maintaining well-being. Health literacy (HL), food literacy (FL), and nutritional literacy (NL) encompass the knowledge, skills, and attitudes needed to make informed health and dietary choices, influencing outcomes beyond direct medical interventions. However, the interrelationships among HL, FL, and NL remain unclear. This systematic review aimed to identify and synthesize the current evidence on whether HL and FL (including NL as a related construct) are associated and whether one can predict the other. Studies were included only if they assessed at least two of these literacies. Methods: The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020) protocol, using eligibility criteria derived from the Population, Interest, and Context (PICo) framework (Population: adults; Interest: HL, FL, and NL; Context: health outcomes and dietary behavior). Searches were performed in MEDLINE (PubMed) and Scopus (Elsevier) using controlled vocabulary and free-text terms covering the key concepts of adults, HL, FL, and NL, as well as health or dietary outcomes. Study quality and potential bias were assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist (QCC). Results: The search yielded 1,491 records; after removing 194 duplicates, 1,297 studies were screened by title, abstract, and keywords. Following stepwise exclusions for irrelevance, missing data, or methodological shortcomings, 17 studies met all inclusion criteria. Across these studies, HL, FL, and NL were consistently associated with dietary behavior, nutritional knowledge, and food-related decision-making. However, the multidimensional nature of FL and NL was rarely captured comprehensively, as most studies focused on specific components rather than the whole constructs. Although some evidence suggested mutual influence between HL and FL/NL, the heterogeneity of measurement tools limited conclusions about the direction of prediction. Discussion and conclusion: The findings indicate that HL, FL, and NL are interrelated and together shape dietary behavior. Literacy-sensitive and context-aware interventions that address both individual capacities and structural factors can improve diet quality and health outcomes, depending on baseline literacy and socioeconomic context. While FL and NL share core competencies with HL, the evidence supports treating them as distinct constructs. Harmonization of measurement instruments and conceptual frameworks is needed to clarify their respective roles in predicting health outcomes in health promotion. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420250652344, identifier PROSPERO (CRD420250652344).