Project Description

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Behavioural and self-report measures of food choice in women who have taken part in a nutrition education program

Written by: Candice Spence 13 November 2020 Researcher: Sofia Monteiro (PhD researcher), Dr James Smith,  Dr Kate Larmuth, Georgina Pujol-Busquets Guillén (PhD researcher)

Institutions: University of Cape Town (UCT), and Max Planck Institute for Research on Collective Goods (MPI)

Background and purpose

Eat Better South Africa (EBSA), the community outreach branch of The Noakes Foundation aims to empower people from under-resourced communities to improve their health by making the best dietary choices available to them. EBSA has run several community nutrition education programs to teach women how to choose healthier foods. Most nutrition studies use diet assessment tools that require self-report e.g. Food Frequency Questionnaire (FFQ), food recall or food diaries. These measures may suffer from bias and noise due to participants’ inattention to what they eat, inability to recall fully and the lack of financial incentive for accuracy. We aimed to validate this FFQ measure with an incentivised behavioural decision task. We tested whether EBSA impacts participants’ food choice when a real decision with real products can be made.

Study overview

This study used an FFQ to collect data on diet in the last month. It also directly measured food choice behaviour in a limited, ecologically valid, retail environment. Participants used a voucher to make purchases from a selection of groceries at a local supermarket. Participants were recruited from the communities where EBSA operates and in future sites. Participants were eligible for the study if they are adult women that have taken part in the EBSA program or are eligible to participate in future EBSA programs but have not yet received an intervention. In the shopping activity, participants made real purchasing decisions with a budget provided by the researchers. They sent a photo of their receipt and a photo of their groceries to the researchers. To analyze the data, items purchased were categorised (Green, Orange and Red) according to the EBSA program’s lists of foods. Compared to the Control group, the EBSA group bought more Green list foods and fewer Red list foods. e.g. EBSA participants were half as likely to buy bread with their shopping voucher. A behavioural measure of food preferences was valuable to corroborate self-report survey instruments, which may suffer from bias since there is no pecuniary incentive to reveal one’s true preferences. We validated the FFQ in our sample by showing that it reflects revealed food preferences. A demographic questionnaire explored food insecurity of households and other socioeconomic factors that influence our participants’ food choices. Despite prevalent food insecurity there was a marked difference in the EBSA group’s diet in line with the program’s LCHF advice.

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