Evans Rebecca, Brealey Jane, Clarke Natasha, Falbe Jennifer, Finlay Amy, Jones Andrew, Thorp Paula, Witham Beth, Witkam Rozemarijn, Robinson Eric
Department of Psychology, Institute of Population Health University of Liverpool, Liverpool, UK.
Department of Psychology, Institute of Population Health University of Liverpool, Liverpool, UK.
Lancet Public Health. 2025 Aug;10(8):e656-e667. doi: 10.1016/S2468-2667(25)00143-4.
High salt intake increases the risk of cardiovascular disease. The salt content of many commonly consumed foods in the out-of-home food sector (eg, restaurants) is excessive, but there are few policy options to address this problem. In this study, we evaluated an emerging policy approach-high salt warning labels on packaged food and resturant menus-for which, to date, there is little supporting evidence from randomised controlled trials.
These randomised controlled trials (one online study and one trial conducted in a real-world setting) were conducted in the UK. For study 1, an online study, participants (stratified by age, sex, and education to be representative of the UK adult population) were eligible if they were a current UK resident, aged 18 years or older, fluent in English, purchased supermarket sandwiches and savoury snacks, and ate out at or ordered from restaurants at least monthly. Exclusion criteria included being pregnant or breastfeeding or having major dietary restrictions. Participants were randomly assigned (1:1:1:1:1) to one of four different salt warning label conditions or to a control condition (QR code). Participants assigned to each group completed three packaged food scenarios and three restaurant ordering scenarios, all online, followed by questionnaires about the labelling and their food choices. The primary outcome was the perceived message effectiveness of salt warning labels. In study 2, the inclusion criteria were similar, except that participants who ate an out-of-home meal at least once a month were recruited. Exclusion criteria were severe dietary allergies and veganism. As in study 1, participants were stratified by age, sex, and education. Participants were randomly assigned (block randomisation with block size ~50) to receive menus with or without salt warning labels, from which they purchased and consumed lunchtime meals in a real-world restaurant. Participants then completed questionnaires. Primary outcomes were perceived message effectiveness and salt awareness. In both studies, perceived message effectiveness was measured with adapted versions of the University of North Carolina Perceived Message Effectiveness Scale. Participants in both studies were paid and masked to the study aims. Study 2 is registered with ClinicalTrials.gov (NCT06458270) and is complete.
In study 1, 2549 participants were randomly assigned to one of four salt warning label groups (red triangle, n=512; black triangle, n=512; red octagon, n=509; and black octagon, n=510) or to the control group (n=506), with data collected between Feb 20, 2024, and April 2, 2024. 158 participants were excluded from analysis, resulting in a final analytic sample of 2391 (1205 [50%] female, 1181 [49%] male, and five [<1%] preferred not to say). All salt warning labels were perceived as significantly more effective at discouraging salt intake than the control, with mean perceived message effectiveness differences of 1·23 (95% CI 1·12-1·34; p <0·0001) for packaged food scenarios and 1·22 (95% CI 1·11-1·33; p <0·0001) for menu scenarios. In study 2, 465 eligible participants were randomly assigned to menus with red triangle salt warning labels next to high-salt items (n=240) or to the restaurant's standard menu (control group; n=225), with data collected between June 5, 2024, and Sept 14, 2024. Full data from 11 participants were excluded from analysis, resulting in a final analytic sample of 454 (246 [54%] female, 203 [45%] male, and five [<1%] missing). The labelled menu was rated as significantly more effective than the control menu in terms of perceived message effectiveness, with a mean difference of 1·00 (95% CI 0·79-1·18; p<0·0001). Participants assigned to the labelled menu condition were significantly more likely to think about the salt content of the meals when ordering than were participants assigned to the standard menu (odds ratio 19·50, 95% CI 8·24-46·16; p<0·0001).
Salt warning labels on restaurant menus are a promising policy option to discourage high salt intake in the out-of-home food sector. Further real-world studies are needed to optimise potential policy to reduce actual salt intake.
National Institute for Health and Care Research Oxford Health Biomedical Research Centre and European Research Council.
高盐摄入会增加心血管疾病风险。外出就餐场所(如餐馆)中许多常见食品的盐含量过高,但解决这一问题的政策选择很少。在本研究中,我们评估了一种新兴的政策方法——在包装食品和餐厅菜单上设置高盐警告标签,迄今为止,随机对照试验几乎没有提供支持证据。
这些随机对照试验(一项在线研究和一项在现实环境中进行的试验)在英国开展。对于研究1(一项在线研究),参与者(按年龄、性别和教育程度分层,以代表英国成年人口)若为英国常住居民,年龄18岁及以上,英语流利,购买超市三明治和咸味零食,且至少每月外出就餐或从餐厅点餐一次,则符合条件。排除标准包括怀孕或哺乳期或有重大饮食限制。参与者被随机分配(1:1:1:1:1)到四种不同的盐警告标签条件之一或对照条件(二维码)。分配到每组的参与者在线完成三个包装食品场景和三个餐厅点餐场景,随后是关于标签及其食物选择的问卷调查。主要结局是盐警告标签的感知信息有效性。在研究2中,纳入标准相似,只是招募了至少每月外出就餐一次的参与者。排除标准为严重食物过敏和纯素食主义。与研究1一样,参与者按年龄、性别和教育程度分层。参与者被随机分配(按约50的区组大小进行区组随机化)接受有或没有盐警告标签的菜单,他们在一家现实世界的餐厅购买并食用午餐。参与者随后完成问卷调查。主要结局是感知信息有效性和盐意识。在两项研究中,感知信息有效性均使用北卡罗来纳大学感知信息有效性量表的改编版本进行测量。两项研究的参与者均获得报酬且对研究目的不知情。研究2已在ClinicalTrials.gov注册(NCT06458270)且已完成。
在研究1中,2549名参与者被随机分配到四个盐警告标签组之一(红色三角形,n = 512;黑色三角形,n = 512;红色八角形,n = 509;黑色八角形,n = 510)或对照组(n = 506),数据收集于2024年2月20日至2024年4月2日之间。158名参与者被排除在分析之外,最终分析样本为2391名(1205名[50%]女性,1181名[49%]男性,5名[<1%]未表明性别)。所有盐警告标签在劝阻盐摄入方面均被认为比对照组显著更有效,包装食品场景下感知信息有效性的平均差异为1.23(95%CI 1.12 - 1.34;p < 0.0001),菜单场景下为1.22(95%CI 1.11 - 1.33;p < 0.0001)。在研究2中,465名符合条件的参与者被随机分配到高盐菜品旁带有红色三角形盐警告标签的菜单组(n = 240)或餐厅标准菜单组(对照组;n = 225),数据收集于2024年6月5日至2024年9月l4日之间。11名参与者的完整数据被排除在分析之外,最终分析样本为454名(246名[54%]女性,203名[45%]男性,5名[<1%]数据缺失)。在感知信息有效性方面,带标签的菜单被评为比对照菜单显著更有效,平均差异为1.00(95%CI 0.79 - 1.18;p < 0.0001)。与分配到标准菜单组的参与者相比,分配到带标签菜单组的参与者在点餐时更有可能考虑餐食的盐含量(比值比19.50,95%CI 8.24 - 46.16;p < 0.0001)。
餐厅菜单上的盐警告标签是减少外出就餐时高盐摄入的一项有前景的政策选择。需要进一步开展现实世界研究以优化潜在政策,从而降低实际盐摄入量。
英国国家卫生与保健研究所牛津健康生物医学研究中心和欧洲研究理事会。