Estimating plate-based model food proportions in adults living in Scotland using short dietary assessment questionnaires

Aim To determine whether a food frequency questionnaire (FFQ) and a short dietary assessment tool can be used to accurately estimate the Eatwell Guide proportions (a plate-based food model) of diets of adults living in Scotland. Methods The cross-sectional study was conducted as a follow up of the 2010 Scottish Health Survey (participants aged 18-65 years old). Proportions of the Eatwell Guide food groups (starchy carbohydrates, fruits and vegetables (F&V), dairy and alternatives, protein foods and oils and spreads) were calculated from the Scottish Health Survey Eating Habits Module (SHeS EHM), Scottish Collaborative Group FFQ (SCG FFQ) and a seven-day estimated food diary (reference method), and compared using the Aitchison method and Wilcoxon Signed-Rank Test. Bland-Altman analyses assessed mean difference and 95% limits of agreement between the methods for each food group. Results Ninety-six adults were included (mean (SD) age = 51.4 (11.1) years; body mass index = 27.1 (4.9) kg/m(2); 58% female). The SCG FFQ scored a lower median Aitchison distance (1.47) than the SHeS EHM (1.99) (P < 0.001), showing greater agreement with the reference method (P < 0.001). Bland-Altman plots also showed better agreement for the SCG FFQ than the SHeS EHM. Poorest agreement was for starchy carbohydrates (both methods), protein foods (SHeS EHM) and dairy (SCG FFQ). Conclusions The SCG FFQ could be used to estimate Eatwell Guide proportions and monitor compliance to the Eatwell Guide recommendations and could be improved with small changes. The SHeS EHM is less suitable, but additional questions on dairy foods, and oils and spreads would improve its ability to estimate the Eatwell Guide proportions.