“Kids Choice” School lunch program increases children's fruit and vegetable acceptance

Abstract

The “Kids Choice” school lunch program used token reinforcement, food choice, and peer participation to increase children's fruit and vegetable consumption without later drops in food preference sometimes found in past research and often called ‘overjustification effects.’ Participants included 188 school children (92 boys, 96 girls; mean age =8.0; 95% Caucasian). After four baseline meals, children were randomly assigned for 12 meals to receive token reinforcement for eating either fruits or vegetables. Observers recorded fruit and vegetable consumption and provided token reinforcement by punching holes into nametags each day children ate their assigned foods, then once a week children could trade these tokens for small prizes. Fruit and vegetable preference ratings were gathered with child interviews during baseline, and during follow-up conditions two weeks and seven months after the token reinforcement program. Consumption increased for fruit and for vegetables and the increases lasted throughout reinforcement conditions. Two weeks after the program, preference ratings showed increases for fruit and for vegetables. Seven months later, fruit and vegetable preferences had returned to baseline levels, suggesting the need for an ongoing school lunch program to keep preferences high, but also showing no signs of “overjustification effects” from the token reinforcement used in the “Kids Choice” school lunch program.

Introduction

Approximately 20% of school-aged children in the United States are overweight or obese (Troiano et al., 1995, Whitney and Rolfes, 2002, p. 552), with increased risk for childhood diabetes, high cholesterol, and high blood pressure (American Dietetic Association, 2000, McGill, 1997;United States Department of Health and Human Services, 2000). Children's consumption of low fat and nutritious foods such as fruits and vegetables is not only associated with reduced risk for health problems, but also with improved cognitive development and social adjustment (Center on Hunger, Poverty, and Nutrition Policy, 1994, Contento et al., 1993, Warden et al., 1982). Most children in the United States eat at least one meal each weekday at school (James, Rienzo, & Franzee, 1996), and school lunch is often their most frequent exposure to fruits and vegetables (Baranowski et al., 1997, Burchett, 2003), making it a unique opportunity for programs that encourage large groups of children to learn to eat and enjoy nutritious foods while in the company of their peers.

By law, school lunches in the United States provide the food groups recommended by federal guidelines (Center on Hunger, Poverty, and Nutrition Policy, 1994), including meat or meat substitute, grains, milk products, and fruits or vegetables. However, school lunches may also include more than 30% of their calories from fat (James, Rienzo, & Franzee, 1996), rather than the 20–30% recommended for children above the age of two (American Dietetic Association, 1999, Butte, 2000, Centers for Disease Control and Prevention, 2000). Also, although fruits and vegetables are often the most nutrient-rich and low-fat foods included in school lunch, 80% of school children do not eat the recommended amounts of them (Gleason and Suitor, 2000, Heimendinger and Van Duyn, 1995), and without intervention their consumption of fruits and vegetables continues to drop by 25% between third and eighth grades (Lytel, Seifert, Greenstein, & McGovern, 2000). Research suggests that girls usually accept fruits and vegetables more than boys do (Corwin, Sargent, Rheaume, & Saunders, 1999), and children usually accept fruit more than vegetables (Baxter and Thompson, 2002, Burchett, 2003, Domel et al., 1993, Edwards and Hartwell, 2002) perhaps because of the greater energy density and sweetness of fruit (Birch, 1979, Drewnowski and Specter, 2004, Gibson and Wardle, 2003). When other high-fat, high-sugar, or high-salt foods are available, children are even less likely to choose to eat fruits and vegetables during school lunch (American Dietetic Association, 2000, Bauer et al., 2004, Cullen et al., 2000). Among the reasons children give for whether they eat fruits and vegetables during school lunch are that they want a choice of foods and they want to eat what their friends eat (James et al., 1996, Marples and Spillman, 1995).

During the last few years, several multi-component school programs have been developed in the United States and Britain to encourage fruit and vegetable acceptance in children: the “Gimme 5” program by Baranowski and colleagues (2000), the “Food Dudes” program by Horne and colleagues (1995), the “Power-Plus” program by Perry and colleagues (1998), the “Know Your Body” program by Resnicow and colleagues (1992), and the “High 5” program by Reynolds, Franklin, Binkley, Raczynski, Harrington and Kirk (2000). These school programs include a variety of components such as nutrition education, increased cafeteria food choices, peer modeling videos, daily letters of encouragement, offers of reinforcement, and/or parental and community involvement. Although these programs have demonstrated some effectiveness for increasing children's fruit and vegetable acceptance, they can be costly, time-consuming, and labor-intensive to put into practice, which may make school staff and parents somewhat reluctant participants (Bauer et al., 2004, Burchett, 2003, Baranowski et al., 2000, Contento et al., 1995, Horne et al., 1995, Lytle and Achterberg, 1995, Perry et al., 1998, Reynolds et al., 2000), and which suggests the need for an effective school program that is simpler in design for greater acceptability and easier implementation. A brief review of past research provides guidance for components most important to include in such a simplified school program (Burchett, 2003).

For example, although many schools include nutrition information as part of their science education programs, past research suggests that nutrition education alone is unlikely to change children's consumption and preference for fruits and vegetables (Burchett, 2003, Contento et al., 1995; Warwick, 1997). Other research suggests children need 8–10 taste exposures to a food before preferences for it increase (Birch and Marlin, 1982, Birch et al., 1987, Sullivan and Birch, 1990, Wardle et al., 2003). One effective method to encourage preschool children to reach this threshold of taste exposures has been to have adults sit with them and verbally encourage each child to “Please have a taste” (Wardle et al., 2003) or “Please try one bite” (Hendy, 1999), although this approach would be impractical for use with large groups of grade school children.

Another effective method to increase children's consumption of fruits and vegetables is by using offers of positive reinforcement, an approach which can be more readily used with large groups (Baranowski et al., 2000, Davis et al., 2000, Hendy, 1999, Horne et al., 1995, Lowe et al., 2001, Perry et al., 1998, Reynolds et al., 2000, Stark et al., 1986, Story et al., 2000). However, some researchers have expressed concern that such offers of positive reinforcement for food consumption may produce later drops in children's food preferences (Birch et al., 1982, Birch et al., 1984, Newman and Layton, 1984), which are often called ‘overjustification effects’ (Lepper, Greene, & Nisbett, 1973). Cognitive explanations are typically offered for such ‘overjustification effects’, with the suggestion that children think that if they must be offered rewards to eat the foods, they must not like them (Newman and Layton, 1984, Newman and Taylor, 1992). Another interpretation for ‘overjustification effects’ that we propose is a simple satiation explanation: If reinforcement pushes consumption of a single food, too much, for too long, children may reach a satiation point and later show reduced preference for that specific food (Rolls, Rolls, Rowe, & Sweeney, 1981). Fortunately, past research and theory provide guidance for components we might include in a school lunch program that could avoid such ‘overjustification effects’ and that could increase both immediate consumption and later preference for fruits and vegetables. These recommended components include use of small and delayed reinforcement, avoidance of satiation effects by offering food choice and requiring that only a small amount of food be eaten to receive reinforcement, and conditions that encourage peer participation and modeling.

For example, one review of the effects of reinforcement on later preference suggests that a school lunch program using small and delayed reinforcement would reduce risk for ‘overjustification effects’ (Eisenberger & Cameron, 1996), perhaps because it makes reinforcement less prominent and provides time for the child to discover pleasing properties of the foods themselves (Hitt, Marriott, & Esser, 1992; Newman & Layton, 1984). Such application of reinforcement could be accomplished with a token reinforcement program in which children receive small tokens for eating fruits and vegetables, which they may later trade in for their choice of small prizes. Eisenberger and Cameron (1996) also suggest that later preference would be enhanced if children were required only to eat a small amount of the food to receive reinforcement, which should also reduce the risk of satiation effects. In support of these suggestions, one study found that young children offered small and delayed prizes for eating only one or two bites of specific foods during preschool lunch reported enhanced preference for those foods one month later (Hendy, 2002). In another study, parents also reported that offering their children small reinforcements for eating foods was effective to increase not only consumption but also lasting preferences (Casey & Rozin, 1989).

Another component for a school lunch program to encourage fruit and vegetable consumption and later preference is food choice as suggested by Self Determination Theory (Deci & Ryan, 1985), which proposes that intrinsic motivation to do any activity, including consumption of fruits and vegetables, would be enhanced by perceived choices surrounding the activity. Although offering food choice is rarely examined as the intervention variable in studies of children's food acceptance, one study found that when teachers gave preschool children a choice of whether or not to eat each lunch food (“Do you want any X,Y,Z?”), food consumption increased as much as when children were offered a special dessert (Hendy, 1999). Similarly, when cafeteria staff gave children the choice of “Which vegetable would (you) like to have?” (Perry, Bishop, Taylor, Davis, Story and Gray, 2004, p. 68), they consumed more vegetables during school lunch.

Finally, Social Cognitive Theory (Bandura, 1997) suggests that children would be more likely to develop ‘self-efficacy’ or confidence to consume fruits and vegetables if the school lunch program included conditions that enhance such confidence, such as repeated exposure to peer models eating the foods. The Group Socialization Theory (Harris, 1995) also emphasizes the importance of peer modeling in the development of any behavior, and research over 25 years has documented the effectiveness of peer models for increasing fruit and vegetable acceptance in children during school lunch (Birch, 1980, Brody and Stoneman, 1981, Hendy, 2002, Hendy and Raudenbush, 2000, Horne et al., 1995; Lowe et al., 2001).

The purpose of the present study was to develop and evaluate the effectiveness of the “Kids Choice” school lunch program to increase children's fruit and vegetable consumption and preference ratings. Unlike past multi-component programs, the present program was designed to enhance acceptability to school staff and parents by including only changes to the school lunch procedures, rather than including changes to the school curriculum or home environment. The “Kids Choice” program was also designed to avoid the later drops in food preference (‘overjustification effects’) sometimes found when food consumption is reinforced by including three components suggested by past research and theory: small and delayed reinforcement, food choice, and conditions that encourage peer participation and modeling. It was hypothesized that with the inclusion of these three components, the “Kids Choice” school lunch program would successfully increase both children's immediate consumption and later preference rating of fruits and vegetables.