Methodological quality of front-of-pack labeling studies: a review plus identification of research challenges

This review evaluates the methodological quality of current front-of-pack labeling research and discusses future research challenges. Peer-reviewed articles were identified using a computerized search of the databases PubMed and Web of Science (ISI) from 1990 to February 2011; reference lists from key published articles were used as well. The quality of the 31 included studies was assessed. The results showed that the methodological quality of published front-of-pack labeling research is generally low to mediocre; objective observational data-based consumer studies were of higher quality than consumer studies relying on self-reports. Experimental studies that included a control group were lacking. The review further revealed a lack of a validated methodology to measure the use of front-of-pack labels and the effects of these labels in real-life settings. In conclusion, few methodologically sound front-of-pack labeling studies are presently available. The highest methodological quality and the greatest public health relevance are achieved by measuring the health effects of front-of-pack labels using biomarkers in a longitudinal, randomized, controlled design in a real-life setting.