Role of Traffic Light Labeling on Point of Purchase Behaviors: A Systematic Review

Background: Traffic Light Labeling (TLL) system is a simple tool to communicate information regarding the nutrients content of food products and has been widely applied to promote public health. However, evidence on the effectiveness of the TLL system on consumers’ choices is conflicting. The present study aims to systematically summarize the effects of TLL on consumers’ point of purchase behaviors. Methods: Five electronic databases, including PubMed/Medline, Scopus, Web of knowledge, the Cochrane library, and Science direct were searched from 2000/01/01 to 2021/11/01. Randomized-controlled trials, in English or Farsi languages, investigating the effects of TLL on choosing healthier foodstuffs or beverages were examined for eligibility and included in the review. Of 6408 potentially relevant publications (including 1255 duplicates), five clinical trials were finally included in the study. Results: The duration of the interventions ranged from 4 to 12 weeks and all studies except one had high methodological quality. Out of 5, three clinical trials did not show positive effects of TLL on customers' choices to purchase healthier food products. Conclusions: The present review showed that TLL without other public health-promoting interventions may have no substantial effects on consumer’s food choice.