Nutri-Score labelling in the out-of-home food sector: evidence on effectiveness from a large, randomised control trial in UK restaurant settings

Background: Over half of UK adults eat food prepared out-of-home (OOH) weekly and the poor nutritional profile of OOH food contributes to ill health. Nutri-Score is a form of interpretative labelling which assigns food products a value of A (healthiest) to E (least healthy) based on nutritional quality, and inclusion on menus could be a public health policy option to reduce obesity. This is the first real-world Randomised Control Trial to test the effectiveness of Nutri-Score alongside calorie labelling on food menus in UK OOH settings. Methods: Adult participants (N=672), majority White (80%) female (63%), with a mean age of 47(SD18) years, were recruited from the local community to visit OOH food businesses to order, consume, and pay for meals. Data collection days were randomised to be control (calorie labelling) or Nutri-Score (calorie labelling with Nutri-Score). Linear mixed models assessed impacts of labelling condition on perceived effectiveness of menu labelling and nutritional quality of food orders. Findings: Scores for perceived effectiveness of labelling were significantly greater in the Nutri-Score condition compared to control (B = 0.21, p=0.010; 95% CI 0.05, 0.37) and food orders were significantly better nutritional quality, indicated by lower Nutrient Profiling Model scores in the Nutri-Score vs. control condition (B = -0.89, p=0.003; 95% CI -1.48, -0.31). Interpretation: Compared to providing calorie labelling alone, inclusion of Nutri-Score could be an effective policy approach to improve nutritional quality of diet and reduce diet-related disease.