Segnalare l'apporto calorico di piatti e bevande sui menu di ristoranti e mense può aiutare a ridurre l'assunzione totale di calorie

Crockett RA, King SE, Marteau TM, Prevost AT, Bignardi G, Roberts NW, Stubbs B, Hollands GJ, Jebb SA.
Cochrane Database of Systematic Reviews 2018, Issue 2. Art. No.: CD009315.

09-03-2018

Segnalare l’apporto calorico dei piatti offerti dalla ristorazione può contribuire a ridurre l’assunzione di calorie. Lo afferma una revisione sistematica della letteratura firmata Cochrane, il Gruppo di analisi dei dati pubblicati riconosciuto in tutto il mondo per l’indipendenza di giudizio e l’affidabilità. Attenzione però: la segnalazione a fianco delle proposte nei vari menu deve essere numerica, espressa in kcal, e non affidata a criteri di valutazione complessiva come le bandierine rosse, o il “sistema del semaforo”.
A queste conclusioni è giunta la revisione di 28 studi di intervento: 11 focalizzati sull’impatto dell’informazione nell’acquisto di cibi e 17 invece sull’effettivo consumo. Intenzione iniziale degli Autori era di considerare tutti i dati ricavati da ricerche condotte in condizioni che riflettono la vita reale, cioè in ristoranti e mense, distributori automatici e rivenditori di cibi pronti ma, data la scarsa qualità degli studi relativi, sono state poi escluse queste ultime due fonti. L’analisi ha incluso anche i risultati degli esperimenti che hanno valutato l’impatto dell’etichettatura calorica sulla scelta di un singolo cibo o bevanda a scelta tra cioccolato, piatto di pasta, diversi soft drink.
In conclusione, si è visto che l’aggiunta del computo calorico alle proposte dei menu favoriva un certo risparmio energetico, quantificabile nell’8% circa di un pasto tipo da 600 kcal, vale a dire 48 kcal in meno.
Gli Autori sottolineano che questi risultati sono incoraggianti, ma non conclusivi. Da un lato, sarà necessario impostare ulteriori studi, che definiscano l’impatto dell’indicazione calorica sulla scelta e sui livelli di assunzione di cibi e bevande nella vita quotidiana, invece che in condizioni sperimentali. Dall’altro, i risultati di questa revisione sistematica incoraggiano la diffusione di informazioni nutrizionali, da inserire in un programma composito destinato al controllo e alla prevenzione di sovrappeso e obesità.

Nutritional labelling for healthier food or non-alcoholic drink purchasing and consumption.

BACKGROUND: Nutritional labelling is advocated as a means to promote healthier food purchasing and consumption, including lower energy intake. Internationally, many different nutritional labelling schemes have been introduced. There is no consensus on whether such labelling is effective in promoting healthier behaviour.
OBJECTIVES: To assess the impact of nutritional labelling for food and non-alcoholic drinks on purchasing and consumption of healthier items. Our secondary objective was to explore possible effect moderators of nutritional labelling on purchasing and consumption.
SEARCH METHODS: We searched 13 electronic databases including CENTRAL, MEDLINE and Embase to 26 April 2017.We also handsearched references and citations and sought unpublished studies through websites and trials registries.
SELECTION CRITERIA: Eligible studies: were randomised or quasi-randomised controlled trials (RCTs/Q-RCTs), controlled before-and-after studies, or interrupted time series (ITS) studies; compared a labelled product (with information on nutrients or energy) with the same product without a nutritional label; assessed objectively measured purchasing or consumption of foods or non-alcoholic drinks in real-world or laboratory settings.
DATA COLLECTION AND ANALYSIS: Two authors independently selected studies for inclusion and extracted study data. We applied the Cochrane ’Risk of bias’ tool and GRADE to assess the quality of evidence.We pooled studies that evaluated similar interventions and outcomes using a random-effects meta-analysis, and we synthesised data from other studies in a narrative summary.
MAIN RESULTS: We included 28 studies, comprising 17 RCTs, 5 Q-RCTs and 6 ITS studies. Most (21/28) took place in the USA, and 19 took place in university settings, 14 of which mainly involved university students or staff. Most (20/28) studies assessed the impact of labelling on menus or menu boards, or nutritional labelling placed on, or adjacent to, a range of foods or drinks from which participants could choose. Eight studies provided participants with only one labelled food or drink option (in which labelling was present on a container or packaging, adjacent to the food or on a display board) and measured the amount consumed. The most frequently assessed labelling type was energy (i.e. calorie) information (12/28). Eleven studies assessed the impact of nutritional labelling on purchasing food or drink options in real-world settings, including purchases from vending machines (one cluster-RCT), grocery stores (one ITS), or restaurants, cafeterias or coffee shops (three RCTs, one QRCT and five ITS). Findings on vending machines and grocery stores were not interpretable, and were rated as very low quality. A meta-analysis of the three RCTs, all of which assessed energy labelling on menus in restaurants, demonstrated a statistically significant reduction of 47 kcal in energy purchased (MD −46.72 kcal, 95% CI −78.35, −15.10, N = 1877). Assuming an average meal of 600 kcal, energy labelling on menus would reduce energy purchased per meal by 7.8% (95% CI 2.5% to 13.1%). The quality of the evidence for these three studies was rated as low, so our confidence in the effect estimate is limited and may change with further studies. Of the remaining six studies, only two (both ITS studies involving energy labels onmenus or menus boards in a coffee shop or cafeteria) were at low risk of bias, and their results support the meta-analysis. The results of the other four studies which were conducted in a restaurant, cafeterias (2 studies) or a coffee shop, were not clearly reported and were at high risk of bias. Seventeen studies assessed the impact of nutritional labels on consumption in artificial settings or scenarios (henceforth referred to as laboratory studies or settings). Of these, eight (all RCTs) assessed the effect of labels on menus or placed on a range of food options. A meta-analysis of these studies did not conclusively demonstrate a reduction in energy consumed during a meal (MD −50 kcal, 95% CI −104.41, 3.88, N = 1705). We rated the quality of the evidence as low, so our confidence in the effect estimate is limited and may change with further studies. Six laboratory studies (four RCTs and two Q-RCTs) assessed the impact of labelling a single food or drink option (such as chocolate, pasta or soft drinks) on energy consumed during a snack or meal. A meta-analysis of these studies did not demonstrate a statistically significant difference in energy (kcal) consumed (SMD 0.05, 95% CI −0.17 to 0.27, N = 732). However, the confidence intervals were wide, suggesting uncertainty in the true effect size. We rated the quality of the evidence as low, so our confidence in the effect estimate is limited and may change with further studies. There was no evidence that nutritional labelling had the unintended harm of increasing energy purchased or consumed. Indirect evidence came from five laboratory studies that involved mislabelling single nutrient content (i.e. placing low energy or low fat labels on high-energy foods) during a snack or meal. A meta-analysis of these studies did not demonstrate a statistically significant increase in energy (kcal) consumed (SMD 0.19, 95% CI −0.14to 0.51, N = 718). The effect was small and the confidence intervals wide, suggesting uncertainty in the true effect size. We rated the quality of the evidence from these studies as very low, providing very little confidence in the effect estimate.
AUTHORS’ CONCLUSIONS: Findings from a small body of low-quality evidence suggest that nutritional labelling comprising energy information on menus may reduce energy purchased in restaurants. The evidence assessing the impact on consumption of energy information on menus or on a range of food options in laboratory settings suggests a similar effect to that observed for purchasing, although the evidence is less definite and also of low quality. Accordingly, and in the absence of observed harms, we tentatively suggest that nutritional labelling on menus in restaurants could be used as part of a wider set of measures to tackle obesity. Additional high-quality research in real-world settings is needed to enable more certain conclusions. Further high-quality research is also needed to address the dearth of evidence from grocery stores and vending machines and to assess  potential moderators of the intervention effect, including socioeconomic status.

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