Salsify experiment: nudging for better eating


UCLouvain psychology researchers have shown that nudging techniques can positively influence eating behaviours, including when it comes to increasing the consumption of a ‘forgotten’ vegetable.

Eating well is the key to good health. Yet many people struggle to apply the principles of a healthy, varied and balanced diet. It is possible, however, to get people to prefer healthy foods, not by trying to convince them or by forbidding certain types of food, but by making sure that they choose what’s good for their health.

What’s ‘nudging’?

The concept of nudging was developed by Richard Thaler, 2017 Nobel Prize winner, and Cass Sunstein. It’s a set of techniques that aim to influence behaviour by modifying the environment. ‘In nudging, the choice is rather unconscious, because the person is influenced without being aware of it’, says Olivier Luminet, professor of health psychology at UCLouvain. ‘It's like product placement in the agri-food sector, a marketing technique that involves placing the product at hand in the consumer’s immediate environment. For example, sweets arranged near supermarket checkouts where children can see them.

Nudging toward heathier food

Can these same techniques be used to encourage the consumption of fruits and vegetables? ‘Strangely, in this context, nudging is not used or studied much’, says Valerie Broers, a doctor of psychology who devoted her thesis to the subject.1In reviewing the literature on the subject, I listed only 20 articles on the nudging of fruits and vegetables. So we conducted nudging experiments at UCLouvain. It shows that it’s quite possible to induce significant changes in food choices. Including for a vegetable as unfamiliar as salsify.

The notion of familiarity plays a major role in our (food) choices. The more a food is known, the more it’s consumed. Salsify is one of the ‘forgotten’ vegetables. To bring it back into the fold, Dr Broers tried an experiment within UCLouvain's university restaurants.

Nudging salsify

On the menu at these restaurants were six different vegetable soups. Before the experiment, salsify was only chosen by 11% of soup consumers. Then for a week Dr Broers offered free tastings of salsify soup. This method of nudging greatly increased demand. Indeed, that week, 43% of soup consumers ordered the salsify. And the next week, when the samples ended, 19% still made that choice. ‘It's almost double the starting score’, Prof. Luminet says. ‘This suggests that not only is nudging effective at increasing the consumption of a healthy food, but that the choice can also persist over time.’2

Salsify: the best prebiotic vegetable

Salsify wasn’t chosen by chance. This root vegetable is considered a prebiotic;(3). Indeed, it’s very rich in inulin (17 g/100 g of salsify), a type of dietary fibre that some probiotics love. This is why salsify is of great interest to Louvain4Nutrition researchers and particularly teams involved in Food4Gut(4). And for good reason: consumed in sufficient quantity – about 12 g per day, the equivalent of 70 g of salsify – inulin can modify the intestinal microbiota by promoting the proliferation of probiotics. Some of these probiotics, such as Akkermansia, have a proven protective effect against obesity and related metabolic disorders (diabetes, high blood pressure, etc.).

Best of all, salsify is farmed and grows easily in Belgium. It can therefore be part of local agricultural production and distribution. In short, salsify is well worth discovering … and eating.

Candice Leblanc

(1) Valérie Broers, ‘A  taste for the unfamiliar: Investigating the individual and environmental determinants of prebiotic vegetable consumption’. PhD thesis defended in 2019 at UCLouvain.
(2) See complete results in V. Broers et al., ‘Investigating the conditions for the effectiveness of nudging: Cue-to-action nudging increases familiar vegetable choice’, Food Quality and Preferences, vol. 71, January 2019.
(3) Artichokes, Jerusalem artichokes and, to a lesser extent, onions are rich in inulin.
(4) Food4Gut is a multidisciplinary and interuniversity research programme. Its goal: to prove that the consumption of prebiotic nutrients can contribute to fighting obesity and associated metabolic disorders (diabetes, high blood pressure, etc.).

A glance at Olivier Luminet's bio

Olivier Luminet is professor of health psychology at UCLouvain and has been FNRS director of research at the Psychological Sciences Research Institute (IPSY) since 2014. He holds a PhD in psychology, obtained in 1998 at UCLouvain. One of his main areas of research is the connection between emotions and health.

A glance at Valérie Broers's bio

Valérie Broers is a researcher in psychology. She holds a master's degree in social psychology and health, obtained in 2014 from the University of Utrecht (the Netherlands), where she was research assistant from 2013 to 2014. She became a doctor of psychology at UCLouvain in 2019.

Her thesis on nudging was funded by Food4Gut, a Walloon Region programme.

Published on March 22, 2019