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The Balance of Health
Environment

Claim

Increasing the share of plant-based options on a menu increases the share of plant-based meals sold, without reducing total sales.

Yes, in canteen settings. Doubling vegetarian availability raised vegetarian sales by roughly 8 to 15 percentage points, and almost nobody noticed the change.

Moderate evidenceHow ratings work

Why this rating: Two field studies in different countries agree on the direction and the mechanism, but both are university catering, the two estimates in the original study differ by roughly a factor of two, and at least one menu-nudge trial in a similar setting found nothing at all.

Supported by good-quality studies that point the same way, but with gaps: fewer studies, mostly observational data, or some inconsistency.

7.8percentage points
Rise in vegetarian meal sales when vegetarian options doubled, experimentalUnited Kingdom, 2019. Source: Garnett et al. (2019).The experimental arm of the same study. About half the observational estimate, which is the honest figure to plan with.

Explanation

In a study of 94,644 meals across university cafeterias, raising the share of vegetarian options from a quarter to a half raised vegetarian sales by about 15 percentage points observationally and 7.8 points in the experimental arm.

A French replication found the odds of a vegetarian choice rose about 2.6 times, with slightly higher satisfaction, and only about 6% of diners noticed anything had changed.

The mechanism is not persuasion. It is that people choose from what is in front of them, and most of them are not making a considered decision at all.

Limitations
  • Both studies are university catering with a captive audience. A supermarket, a pub or a wedding is a different problem.
  • Nykänen and colleagues found that dish-of-the-day and menu-sequence nudges changed neither dish choice nor the weight of meat served.
  • Plan with the experimental figure, not the observational one.
Methodology
  • Sales data by meal, compared before and after a change in the share of vegetarian options, with an experimental arm assigning the change across sites.

Sources for this claim

Each source links to our record of what it found, its limitations and what we used it for, with a link to the original.

  1. 1
    Impact of increasing vegetarian availability on meal selection and sales in cafeterias

    Emma S. Garnett, Andrew Balmford, Chris Sandbrook et al. (2019). Proceedings of the National Academy of Sciences.

    Peer Reviewed StudyRandomised Controlled TrialStrong evidenceView original ↗
  2. 2
    Increasing vegetarian availability in a French university restaurant

    (2023). French university catering research group.

    Peer Reviewed StudyRandomised Controlled TrialModerate evidence
  3. 3
    Nudging towards plant-based main dishes in a university restaurant

    (2022). University research group.

    Peer Reviewed StudyRandomised Controlled TrialModerate evidence