| Abstract: |
Background: Overconsumption of food and consumption of any amount of alcohol
increases the risk of non-communicable diseases. Calorie (energy) labelling is
advocated as a means to reduce energy intake from food and alcoholic drinks.
However, there is continued uncertainty about these potential impacts, with a
2018 Cochrane review identifying only a small body of low-certainty evidence.
This review updates and extends the 2018 Cochrane review to provide a timely
reassessment of evidence for the effects of calorie labelling on people's
selection and consumption of food or alcoholic drinks. Objectives: – To
estimate the effect of calorie labelling for food (including non-alcoholic
drinks) and alcoholic drinks on selection (with or without purchasing) and
consumption. – To assess possible modifiers – label type, setting, and
socioeconomic status – of the effect of calorie labelling on selection (with
or without purchasing) and consumption of food and alcohol. Search methods: We
searched CENTRAL, MEDLINE, Embase, PsycINFO, five other published or grey
literature databases, trial registries, and key websites, followed by
backwards and forwards citation searches. Using a semi-automated workflow, we
searched for and selected records and corresponding reports of eligible
studies, with these searches current to 2 August 2021. Updated searches were
conducted in September 2023 but their results are not fully integrated into
this version of the review. Selection criteria: Eligible studies were
randomised controlled trials (RCTs) or quasi-RCTs with between-subjects
(parallel group) or within-subjects (cross-over) designs, interrupted time
series studies, or controlled before-after studies comparing calorie labelling
with no calorie labelling, applied to food (including non-alcoholic drinks) or
alcoholic drinks. Eligible studies also needed to objectively measure
participants' selection (with or without purchasing) or consumption, in
real-world, naturalistic laboratory, or laboratory settings. Data collection
and analysis: Two review authors independently selected studies for inclusion
and extracted study data. We applied the Cochrane RoB 2 tool and ROBINS-I to
assess risk of bias in included studies. Where possible, we used
(random-effects) meta-analyses to estimate summary effect sizes as
standardised mean differences (SMDs) with 95% confidence intervals (CIs), and
subgroup analyses to investigate potential effect modifiers, including study,
intervention, and participant characteristics. We synthesised data from other
studies in a narrative summary. We rated the certainty of evidence using
GRADE. Main results: We included 25 studies (23 food, 2 alcohol and food),
comprising 18 RCTs, one quasi-RCT, two interrupted time series studies, and
four controlled before-after studies. Most studies were conducted in
real-world field settings (16/25, with 13 of these in restaurants or
cafeterias and three in supermarkets); six studies were conducted in
naturalistic laboratories that attempted to mimic a real-world setting; and
three studies were conducted in laboratory settings. Most studies assessed the
impact of calorie labelling on menus or menu boards (18/25); six studies
assessed the impact of calorie labelling directly on, or placed adjacent to,
products or their packaging; and one study assessed labels on both menus and
on product packaging. The most frequently assessed labelling type was simple
calorie labelling (20/25), with other studies assessing calorie labelling with
information about at least one other nutrient, or calories with physical
activity calorie equivalent (PACE) labelling (or both). Twenty-four studies
were conducted in high-income countries, with 15 in the USA, six in the UK,
one in Ireland, one in France, and one in Canada. Most studies (18/25) were
conducted in high socioeconomic status populations, while six studies included
both low and high socioeconomic groups, and one study included only
participants from low socioeconomic groups. Twenty-four studies included a
measure of selection of food (with or without purchasing), most of which
measured selection with purchasing (17/24), and eight studies included a
measure of consumption of food. Calorie labelling of food led to a small
reduction in energy selected (SMD −0.06, 95% CI −0.08 to −0.03; 16 randomised
studies, 19 comparisons, 9850 participants; high-certainty evidence), with
near-identical effects when including only studies at low risk of bias, and
when including only studies of selection with purchasing. There may be a
larger reduction in consumption (SMD −0.19, 95% CI −0.33 to −0.05; 8
randomised studies, 10 comparisons, 2134 participants; low-certainty
evidence). These effect sizes suggest that, for an average meal of 600 kcal,
adults exposed to calorie labelling would select 11 kcal less (equivalent to a
1.8% reduction), and consume 35 kcal less (equivalent to a 5.9% reduction).
The direction of effect observed in the six non-randomised studies was broadly
consistent with that observed in the 16 randomised studies. Only two studies
focused on alcoholic drinks, and these studies also included a measure of
selection of food (including non-alcoholic drinks). Their results were
inconclusive, with inconsistent effects and wide 95% CIs encompassing both
harm and benefit, and the evidence was of very low certainty. Authors'
conclusions: Current evidence suggests that calorie labelling of food
(including non-alcoholic drinks) on menus, products, and packaging leads to
small reductions in energy selected and purchased, with potentially meaningful
impacts on population health when applied at scale. The evidence assessing the
impact of calorie labelling of food on consumption suggests a similar effect
to that observed for selection and purchasing, although there is less evidence
and it is of lower certainty. There is insufficient evidence to estimate the
effect of calorie labelling of alcoholic drinks, and more high-quality studies
are needed. Further research is needed to assess potential moderators of the
intervention effect observed for food, particularly socioeconomic status.
Wider potential effects of implementation that are not assessed by this review
also merit further examination, including systemic impacts of calorie
labelling on industry actions, and potential individual harms and benefits. |