Validation of a Brief Vegetable Variety Questionnaire to Assess Diet Quality

Obtaining estimates of food intake via the 24-h dietary recall is laborious and expensive. Simpler methods for estimating dietary quality are needed in clinical settings and for evaluating nutrition education interventions.

The objective of this study was to validate a simple, pictorial tool for assessing diet quality using vegetable variety as the indicator.

The My Veggies tool, containing 28 pictures of vegetables and items about food preparation, eating at home, and eating fast food, was administered to 258 healthy adults aged 18-65 y. To assess convergent validity, 3 dietary recalls were used to calculate the Healthy Eating Index (HEI) 2015 and dietary energy density (DED), both of which serve as measures of diet quality. To determine criterion validity, height, weight, and body composition (as measured by dual-energy X-ray absorptiometry) were assessed. Using cluster analysis, responses to My Veggies generated 3 vegetable variety groups: high variety (HV; n = 84), medium variety (MV; n = 107), and low variety (LV; n = 67). Values for HEI, DED, body mass index (BMI) (in kg/m²), and body composition were compared across the variety groups to determine whether differences existed.

Demographic characteristics did not differ between the variety groups. The LV group had lower total HEI score (median = 54.4; IQR = 15.6) than HV (62.1; 17.3) and MV (68.0; 18.6) groups (P < 0.0001 for both). The LV variety group had a higher DED score (median = 2.6; IQR = 0.4) than the HV (2.2; 0.6) and MV (2.3; 0.5) groups (P < 0.0001 for both). Both HV and MV groups reported cooking from scratch more often than LV group (P < 0.0001), and HV and MV reported eating out and fast food less frequently than LV (analysis of variance, P < 0.0001; post hoc mean comparisons of HV and MV compared with LV, P < 0.0001). The LV group had higher BMI (P < 0.003) and body fat percentage (P < 0.005) than MV and HV groups.

This study provides evidence of the convergent and criterion validity of a simple, pictorial assessment tool for evaluating diet quality based on vegetable variety. Overall, adults with lower vegetable variety scores had lower diet quality and higher body mass index and fat mass. My Veggies can be used by health professionals as an evaluation tool for community nutrition education interventions or as a screener for counseling in a clinical setting.This trial was registered at clinicaltrials.gov as NCT02367287.