Salt Warning Label Restaurant Study

NCT06458270 | Completed

• 1 other identifier: rfj78drdsu52lsbw3kztnbpne8xdao
• Study Type: interventional
• Target: 465
• Locations: 1 country
• Sites: 1

Brief Summary

This between-subjects randomised controlled trial aims to test the effect of a menu featuring salt warning labels on perceived message effectiveness relative to a menu with no labels in a real-world restaurant environment. The study will also act as a pilot experiment for examining the impact of the salt warning label on food choice and subsequent salt intake in real-world conditions. Primary objectives:

• To measure the PME of a menu featuring salt warning labels relative to a menu with no labels
• To measure label awareness, perceived knowledge gain, and perceived influence of the label on food choice Secondary objectives:
• To identify whether there is an effect of the salt warning label on:
• Food choice (label/no label)
• Total salt selected
• Total salt intake
• To examine support for the introduction of a salt warning label policy in the UK

Conditions

Food Selection

Outcome Measures

Primary Outcomes (6)

• Perceived message effectiveness (PME)

  Participants will answer 3 PME questions using a Likert scale ranging from 1 - 5 anchored by "not at all" and "a great deal": Prompt: "Think back to the menu that you ordered from…" "The menu made me concerned about the health effects of consuming items high in salt", "The menu made consuming items high in salt seem unpleasant", "The menu discouraged me from wanting to consume items high in salt". The mean response to the three items will be calculated.

  Post - meal assessment (within 10 minutes)

• Label awareness

  "Did you notice any warning labels next to any of the menu items when making your meal selection?" (yes/no). If \[yes\], "What did the label tell you about?" Response options: Healthy items, Organic, Calcium, Sustainable, Added sugars, Vegetarian, Unhealthy items, Salt, Fibre, Gluten Free, None of these, Not sure. If \[yes\], "Please describe what the label said" (open text response). Responses that mention high in salt or similar will be coded as aware.

  Post - meal assessment (within 10 minutes)

• Salt awareness

  "Did you think about the salt content of the meals when making your selection?" (yes/no)

  Post - meal assessment (within 10 minutes)

• Perceived knowledge gain

  For this question, both conditions will be shown an image of the labelled menu. "Did you learn something new from the salt labels on the menu?" (yes/no).

  Post - meal assessment (within 10 minutes)

• Perceived influence

  For this question, both conditions will be shown an image of the labelled menu, and some question phrasing is slightly altered. "Did the salt label influence which food you ordered from the menu" (yes/no). "If \[yes\], how did the salt label influence your choice?" Response options: I avoided choosing a meal high in salt; I chose a meal high in salt; Other (free text response) Control: "Would the salt label have influenced what food you ordered from the menu?" (yes/no) If \[yes\], how would the salt label have influenced your choice? Response options: I would have avoided choosing a meal high in salt; I would have chosen a meal high in salt; Other (free text response)

  Post - meal assessment (within 10 minutes)

• Policy support

  For this question, the both conditions will be shown an image of the labelled menu. If the UK Government introduced policy requiring restaurant menu items high in salt to feature these labels, how would you feel?" Likert scale ranging from 1 - 5 anchored by "strongly oppose" and "strongly support".

  Post - meal assessment (within 10 minutes)

Secondary Outcomes (5)

• Total salt purchased

  Post - meal assessment (within 10 minutes)

• Labelled item selected

  Post - meal assessment (within 10 minutes)

• Total salt consumed

  Post - meal assessment (within 10 minutes)

• Later salt intake

  Follow-up assessment (next morning, 8AM, to be completed within 24 hours)

• Other macronutrient intake

  Post - meal assessment (within 10 minutes)

Other Outcomes (2)

• Food choice motives

  Post - meal assessment (within 10 minutes)

• Aim guessing

  Post - meal assessment (within 10 minutes)

Study Arms (2)

Label group

EXPERIMENTAL

Participants will receive a manipulated restaurant menu featuring salt warning labels next to menu items that are high in salt.

Behavioral: Salt warning label

Control group (no label)

NO INTERVENTION

Participants will receive a standard restaurant menu (no labels).

Interventions

Salt warning label BEHAVIORAL

A salt warning label will feature on the restaurant menu next to menu items that are high in salt (\>3g, more than 50% of guideline daily amount \[GDA\] in the UK).

Label group

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Are a UK resident
• Are aged 18 years and above
• Are fluent in English
• Eat an out-of-home meal at least once a month on average
• Have no dietary allergies
• Are not vegan

Sponsors & Collaborators

• University of Liverpool: lead
• National Institute for Health Research, United Kingdom: collaborator

Study Sites (1)

University of Liverpool

Liverpool, Merseyside, L69 7ZA, United Kingdom

Location

Related Publications (1)

• Evans R, Brealey J, Clarke N, Falbe J, Finlay A, Jones A, Thorp P, Witham B, Witkam R, Robinson E. Salt warning labels in the out-of-home food sector: online and real-world randomised controlled trials in the UK. Lancet Public Health. 2025 Aug;10(8):e656-e667. doi: 10.1016/S2468-2667(25)00143-4.

  PMID: 40738552 DERIVED

MeSH Terms

Conditions

Food Preferences

Condition Hierarchy (Ancestors)

Feeding Behavior; Behavior

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor Eric Robinson

Study Record Dates

• First Submitted: June 3, 2024
• First Posted: June 13, 2024
• Study Start: June 3, 2024
• Primary Completion: September 14, 2024
• Study Completion: September 14, 2024
• Last Updated: April 2, 2025

Record last verified: 2025-03

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, ANALYTIC CODE

Locations

GB (1)