The comparative validity of a brief diet screening tool for adults: The Fruit And Vegetable VAriety index (FAVVA)

Abstract

A brief assessment tool on frequency and variety of fruit and vegetable intake could provide a cost-effective and sustainable approach to improving diet. The primary aim was to evaluate the comparative validity of a brief index of Fruit And Vegetable VAriety (FAVVA) relative to food and nutrient intakes derived from a comprehensive food frequency questionnaire (FFQ). The secondary aim was to evaluate the FAVVA index in relation to fasting plasma carotenoid concentrations. Dietary intakes and fasting plasma carotenoid concentrations of 99 overweight and obese adults (49.5% female; 44.6±9.9 years) were assessed at baseline and 3-months. Food and nutrient intakes were assessed using the Australian Eating Survey (AES) FFQ. The FAVVA index was derived from a sub-set of 35 AES questions related to fruit and vegetable intake frequency and variety. Associations were assessed using Spearman's correlation coefficients and linear regression analysis, and agreement using weighted kappa (Kw). Total FAVVA score demonstrated moderate to strong, significant (all p<0.01) correlations with total daily intakes of vegetables (r=0.75), vitamin C (r=0.71), fruit (r=0.66), vitamin A (r=0.49), fibre (r=0.49), potassium (r=0.46), magnesium (r=0.39), iron (r=0.26), riboflavin (r=0.24), calcium (r=0.23), zinc (r=0.20) and niacin equivalent (r=0.20). These associations remained significant in the adjusted regression analyses and agreement testing. Total FAVVA was significantly correlated with plasma carotenoid concentrations (μg/dL) of α-carotene (r=0.22, p<0.01), β-carotene (r=0.26, p<0.001), β-cryptoxanthin (r=0.22, p<0.01) and total carotenoids (r=0.18, p<0.05). The associations with α-carotene (β=0.09, p<0.001), β-carotene (β=0.42, p<0.05) and total plasma carotenoids (β=0.85, p<0.05) remained significant in the adjusted regression analyses and for agreement testing. FAVVA is suitable as a brief tool to rank frequency and variety of fruit and vegetable intake.