Methods to assess front-of-pack label effects on consumer choice, purchase and purchasing intention

Introduction/Objectives

Understanding methodological aspects of front-of-pack nutrition labelling (FoPNL) research is essential to identify quality indicators in published studies and support evidence-based policy-making. This study aims to describe designs and key methodological parameters of interventional studies assessing FoPNL effects on adults’ food choices, purchasing intentions, or actual purchases.

Methods

A systematic review was conducted following PRISMA guidelines. Searches were performed in PubMed, Scopus, Cochrane, Embase, and Web of Science (March 13, 2025) and JSTOR (March 17, 2025). Screening and selection were done in duplicate with consensus with a third reviewer. Data extraction was partially duplicated using a piloted form and analyzed descriptively. Included studies assessed FoPNL alone or with other interventions versus no label or alternative labels. Outcomes included food choices, purchases, or intentions. Studies in real or virtual settings using real or mock products were eligible; out-of-home studies were included only when pre-packaged products were tested.

Results

From 13,245 records, 126 studies were included. Four main designs were identified: RCTs with discrete choice tasks (n = 62), RCTs with supermarket-like tasks (n = 31), quasi-experiments with discrete choice tasks (n = 17), and quasi-experiments using purchase data (n = 16). Most studies were online presenting products digitally. Product categories typically ranged from 6–10, but supermarket-like RCTs included 10–40. Product sets varied widely: 2–5 products in discrete choice studies versus 50 to > 10,000 in supermarket simulations. Real products were most common, though mock products were frequent in discrete choice designs. Outcomes focused on choice or intention in experimental studies, and actual purchases in quasi-experiments.

Conclusions

Heterogeneity in study designs, settings, and outcomes highlights need to clarify best-practice designs and methods for policy-making.

Key messages

• FoPNL studies vary widely in design, methods, settings, and product exposure, limiting comparability.

• Standardization of methods and quality criteria is needed to support robust research and effective policy use.