NC219: Using Stage Based Interventions to Increase Fruit and Vegetable Intake in Young Adults
Statement of Issues and Justification
Americans do not eat enough vegetables and fruits to promote optimal health and reduce the risk of chronic disease. The transition from parental control to independent adulthood that occurs for most young people between the ages of 18 and 24 is a critical stage for developing food habits affecting health throughout life. In addition, many young adults are starting their own families and are modeling behaviors that will influence the next generation. Intervention materials tailored to stage of change have been effective in promoting behavior change for a variety of behaviors, but have not been applied to increasing the consumption of vegetables and fruits in young adults. In addition, most stage-based interventions have focused on homogeneous populations and have not been replicated with diverse populations.Justification
Consumption of vegetables and fruits strongly relates to a decreased risk of developing chronic diseases (1,2). The 2000 edition of the Dietary Guidelines for Americans places great importance on increasing consumption of foods from plant origins (3). However, it is clear from market research and national surveys that the typical American diet includes too few vegetables and fruits to promote optimal health (4-8). It is imperative that effective methods for promoting increases in both fruit and vegetable intakes are developed. Many Americans are familiar with the Food Guide Pyramid but they dont know important concepts such as what constitutes a serving (9). Few Americans are aware of the underlying message that consuming more than the minimal number of servings and consuming a greater variety of fruits and vegetables are among the most powerful dietary strategies for preventing chronic disease. Although it is possible that more targeted knowledge-based messages could be effective, researchers have found that knowledge alone is insufficient to promote behavior change for the majority of the population (10). While the Stages of Change Model shows promise for promoting change in dietary behavior, it has only recently been employed for promoting increases in fruit and vegetable intakes (11-13). Young adults between the ages of 18 to 24 are similar to older adults in their insufficient consumption of fruits and vegetables (4, 14-16). Young adults are a particularly vulnerable group because 1) the food habits they form at this transitional stage of life set the stage for their later years, 2) intake of fruit and vegetables starting at this age will have the maximum preventive potential, and 3) many of these young adults will have families and will model dietary behavior for their children.
Extent of the problem
Young adults are at a critical stage of development and are making the transition from parental control of their food intake to being responsible for their own, and often their children's, food intake (17-19). Results from national and regional surveys show the typical 18 to 24 year old diet is low in vegetables and fruits (4, 6, 14-16). Vegetables and fruits consumed tend to lack variety with habitual intake of a limited number of food items from each group (16). Food habits adopted during the young adult years have long-term effects on health throughout life and are the habits taught to the next generation of children. The results of the proposed research are intended to diminish the risk of chronic disease by promoting increased consumption of a wide variety of vegetables and fruits for young adults.
Need for cooperative work
In previous studies (NC 200 and 219 Regional Research) we have established a strong record of collaborative research as demonstrated by our publication record with multiple authors from different institutions (see Critical Review). These projects were developed and implemented collaboratively. For example, the survey completed last year was developed and implemented in ten states using the same instrument and survey design. We recruited 2,930 subjects with a range of 244 to 367 per state. Recruiting a sample of this size would have been prohibitive for any single institution. In addition, there were significant differences in demographic variables between states. An average of 28.5% were non-students with a high of 33% in ME and a low of 20% in NY. ME also had the highest proportion rural (52%) and NY the lowest (9%) with an average of 23%. Although overall 90% of the sample was Caucasian, AL had 45% African Americans and WI only 1%. The proposed project will focus on underserved populations such as African American, Hispanic, economically disadvantaged, and non-college students. Participating institutions will form cooperative arrangements with programs such as EFNEP, WIC, and Food Stamps to help in intervention development and recruitment. Using the same assessment methodology and intervention design, we can compare effectiveness of the intervention between populations as well as assess overall intervention effectiveness. This research could not be conducted without a collaborative effort across multiple states. The cooperation of a multi-state regional project benefits the proposed research by offering access to a wider variety of young adults than would be possible at a single institution. The larger and more diverse sample afforded through cooperative work increases the power and generalizibility of the results.
Benefits
In the proposed research we will demonstrate a benefit to consumers in the target audience by their increased consumption of vegetables and fruits. The qualitative study planned for Year 01 will provide data about preferred methods of delivery of nutrition information in diverse populations that can benefit programs working with these populations. Methods developed and found effective for promoting behavior change in food intake will benefit health educators who can adapt the methods for use with their audiences. This theory-based research will test the efficacy of stage tailored methods for behavior change in diverse populations. The methods developed may demonstrate a benefit to those in food marketing by providing tested ways to increase targeted food purchases. The methods used in this project should be of interest to agencies within USDA and NIH. Successful completion of this project would provide much needed information about the Stages of Change model and about the efficacy of the model for interventions to promote healthful food choices as part of a lifestyle pattern to prevent chronic diseases in diverse populations. The proposed project with its emphasis on diversity and systematic data collection and analysis will increase the possibility of obtaining additional grant funding in this area.
Impact on science
The proposed research is unique in at least two ways. Young adults as an age group have been neglected, perhaps due to their apparent health and vigor. The few investigators who have examined food habits and factors influencing food intake have focused primarily on college students. In our research, NC 200 and 219 gained access to young adults who were not college students. Our findings revealed strong influences on food intake and that food intake and influences on food intake differed depending on student status. The proposed research would further the advancement of our understanding of what motivates young adults to change food habits. Of greater importance, newer models for the study of behavior change, most notably the Stages of Change model, have shown promise for promoting some kinds of behavior change (20-23). Very few researchers have used the model to increase consumption of fruits and vegetables and fewer studies have been conducted with young adults as the target group. The proposed research would be one of the first to develop and test model-based nutrition interventions for young adults in diverse populations.
Other impacts
Early intervention with young adults for improvement in personal health status should lower total costs of health care for the nation over the long-term (24). Young adults who increase their consumption of vegetables and fruits would, by virtue of being a role model, transfer this food habit to their children and peers (17). There is evidence that health habits tend to cluster, suggesting the possibility that adopting healthier eating habits may lead to other positive health habits such as increased exercise or decreased smoking (24). Higher consumption of vegetables and fruits would provide an economic benefit to producers (25). While it is possible that certain individuals who increase their vegetable and fruit intake might concurrently decrease their intake of dairy and meat products, our research focuses on increasing consumption of plant products rather than decreasing consumption of other food products. An increased consumption of vegetables and fruits would result in an increased level of dietary fiber, folic acid and other nutrients in which the typical U.S. diet tends to be inadequate as well as increasing consumption of phytochemicals with disease preventing potential (4).
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