Perceived Effectiveness of Salt Warning Labels on a UK Restaurant Menu: a Real-world Pilot Experiment
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- University of Liverpool
- Enrollment
- 465
- Locations
- 1
- Primary Endpoint
- Perceived message effectiveness (PME)
Study Overview
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
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Other
- Masking
- Single (Participant)
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •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
Exclusion Criteria
- Not provided
Arms & Interventions
Label group
Participants will receive a manipulated restaurant menu featuring salt warning labels next to menu items that are high in salt.
Intervention: Salt warning label (Behavioral)
Control group (no label)
Participants will receive a standard restaurant menu (no labels).
Outcomes
Primary Outcomes
Perceived message effectiveness (PME)
Time Frame: Post - meal assessment (within 10 minutes)
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.
Salt awareness
Time Frame: Post - meal assessment (within 10 minutes)
"Did you think about the salt content of the meals when making your selection?" (yes/no)
Perceived knowledge gain
Time Frame: Post - meal assessment (within 10 minutes)
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).
Policy support
Time Frame: Post - meal assessment (within 10 minutes)
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".
Label awareness
Time Frame: Post - meal assessment (within 10 minutes)
"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.
Perceived influence
Time Frame: Post - meal assessment (within 10 minutes)
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)
Secondary Outcomes
- Labelled item selected(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))
- Total salt purchased(Post - meal assessment (within 10 minutes))
- Total salt consumed(Post - meal assessment (within 10 minutes))
Investigators
Eric Robinson
Professor Eric Robinson
University of Liverpool