Modest evidence that nutritional labelling may reduce the amount of calories purchased in restaurants, cafeterias and coffee shops was found by the Cochrane research team - writing in the Cochrane Database of Systematic Reviews.
Combining the results from 3 studies in this setting revealed that labelling could potentially reduce the energy content of food purchased by 48 calories. However, the quality of studies was poor, and subject to potential biases.
The complete review consisted of 28 studies, 21 of which were conducted in the US, while only two were UK-based. Eleven studies assessed the impact of nutritional labelling on purchasing food or drink options in real-world settings, including purchases from vending machines), grocery stores, or restaurants, cafeterias or coffee shops.
None of the other trials involving real-life settings showed any statistically significant results. Studies were generally low quality and in some cases failed to report results clearly.
The other 17 studies assessed the effect of labelling on menus or food in artificial scenarios, either for single or multiple food options available. None of these 17 studies provided any significant evidence to support lower calorie consumption resulting from labelling. Furthermore, study quality was very low throughout.
Even though the evidence from the studies was limited, possibly due to the quality of individual trials, the review team nevertheless argued that labelling could be helpful if used as part of a wider action plan to reduce excessive calorie intake.
"This evidence suggests that using nutritional labelling could help reduce calorie intake and make a useful impact as part of a wider set of measures aimed at tackling obesity," said Professor Theresa Marteau, Director of the Behaviour and Health Research Unit at the University of Cambridge.
"There is no 'magic bullet' to solve the obesity problem, so while calorie labelling may help, other measures to reduce calorie intake are also needed," she added.
Broad agreement from experts
Experts were widely supportive of the labelling initiative, but again emphasised the need to use other anti-obesity measures as well.
“This intervention needs to be used alongside other interventions addressing both calorie intake and expenditure. It is one piece of the intervention jigsaw that may help in addressing the obesity crisis,” said Dr. Amelia Lake, Associate Director of Fuse: the Centre for Translational Research in Public Health, and Dietitian and Reader in Public Health Nutrition at Teesside University,
“The evidence is not strong that nutritional labelling, especially of energy (calories), has a significant impact on consumer choice. It is imperative, however, that as much information is given at point of selection so that consumers can make informed comparative choices,” commented Brian Ratcliffe, Emeritus Professor of Nutrition at Robert Gordon University.
“Even modest reductions of up to 10% in energy intake when eating out could help individuals who are trying to control their calories. Some of the studies reviewed showed this level of reduction is possible,” he added.
Further high quality studies needed
Additional research using better quality studies examining a number of aspects of the impact of labelling, suggested Peymané Adab, Professor of Public Health at the University of Birmingham,
“The overview has shown that higher quality studies are needed to increase our confidence about the benefits of labelling. In particular, we don’t know whether those who alter their food purchasing or consumption are those that would most benefit or whether such labelling could differentially benefit only subgroups of the population, thus widening inequalities.
“We also don’t know whether nutritional labels could have other impacts such as substitution with less healthy alternatives or on total calories consumed over a longer time period. Information on calories alone does not tell us about the overall quality of the food (e.g. amount of salt, vitamins etc.) and we need more research to know whether or not choosing lower calorie foods at one point in the day could lead to compensatory overconsumption by choosing something more highly calorific later.
“Finally, the effects of nutritional labelling on the reformulation of products by food manufacturers and menu choices offered by restauranteurs also need to be studied,” Adab concluded.
Source: Cochrane Database of Systematic Reviews
Published online: 2018, issue 2, article no: CD009315, doi: 10.1002/14651858.CD009315.pub2.
“Nutritional labelling for healthier food or non-alcoholic drink purchasing and consumption”
Authors: Crockett RA, King SE, Marteau TM, Prevost AT, Bignardi G, Roberts NW, Stubbs B, Hollands GJ, Jebb SA.