Promoting vegetable intake in preschool children: Independent and combined effects of portion size and flavor enhancement

Abstract

This study investigated the independent and combined effects on preschool children's vegetable intake of serving a larger portion of vegetables and enhancing their flavor. In a crossover design, lunch was served in childcare centers once a week for four weeks to 67 children aged 3-5 y (26 boys, 41 girls). The meal consisted of two familiar vegetables (broccoli and corn) served with fish sticks, rice, ketchup, applesauce, and milk. Across the four meals, we varied the portion of vegetables (60 or 120 g total weight, served as equal weights of broccoli and corn) and served them either plain or enhanced (6.6% light butter and 0.5% salt by weight). All meals were consumed ad libitum and were weighed to determine intake. Doubling the portion of vegetables led to greater consumption of both broccoli and corn (both p < 0.0001) and increased meal vegetable intake by 68% (mean ± SEM 21 ± 3 g). Enhancing vegetables with butter and salt, however, did not influence their intake (p = 0.13), nor did flavor enhancement modify the effect of portion size on intake (p = 0.10). Intake of other meal components did not change when the vegetable portion was doubled (p = 0.57); thus, for the entire meal, the increase in vegetable consumption led to a 5% increase in energy intake (13 ± 5 kcal; p = 0.02). Ratings indicated that children had similar liking for the plain and enhanced versions of each vegetable (both p > 0.31). All versions of vegetables were well-liked, as indicated by ≥ 76% of the children rating them as "yummy" or "just okay". Serving a larger portion of vegetables at a meal was an effective strategy to promote vegetable intake in children, but when well-liked vegetables were served, adding butter and salt was not necessary to increase consumption.

Trial registration: ClinicalTrials.gov NCT03926065.

Keywords: Eating behavior; Energy intake; Liking; Portion size; Preschool children; Vegetable intake.

Figure 1

Mean (±SEM) vegetable intake (g) consumed at lunch by 67 preschool children. Across four meals, vegetables were served at two levels of portion size (100% [30 g of each vegetable] or 200% [60 g of each vegetable]) and two levels of flavor enhancement (plain or enhanced by adding butter and salt). *Mean vegetable intake in the 200% portion size conditions was significantly greater than mean intake in the 100% portion size conditions (p < 0.0001). Enhancing the flavor of vegetables did not influence vegetable intake (p = 0.13) nor modify the effect of serving a larger portion on vegetable intake (interaction p = 0.10).

Figure 2

Mean (±SEM) energy intake (kcal) consumed at lunch by 67 preschool children. Across four meals, vegetables were served at two levels of portion size (100% [30 g of each vegetable] or 200% [60 g of each vegetable]) and two levels of flavor enhancement (plain or enhanced by adding butter and salt). * Mean energy intake in the 200% portion size conditions was significantly greater than mean energy intake in the 100% portion size conditions (p = 0.02). Enhancing the flavor of vegetables did not influence meal energy intake (p = 0.10).

Figure 3

Influence of parental scores for Food Fussiness on the relation between portion size and vegetable intake in 67 preschool children. Across four meals, vegetables were served at two levels of portion size (100% [30 g of each vegetable] or 200% [60 g of each vegetable]) and two levels of flavor enhancement (plain or enhanced by adding butter and salt). Results from analysis of covariance showed that the slope of the regression line for the 200% portions was significantly steeper than the slope for the 100% portions (adjusted p = 0.03). Thus, children who were rated higher in food fussiness had smaller increases in vegetable intake when the portion was doubled. The Food Fussiness scale is from the Children’s Eating Behaviour Questionnaire (Wardle et al., 2001).