Application of an ecological model to dairy product consumption behavior among eighth graders in Taipei, Taiwan

Abstract

Calcium is important to bone health as well as related to a number of health problems such as osteoporosis, hypertension, cardiovascular disease, and some cancers. Calcium intake level was far below the Dietary Reference Intake and dairy product consumption was inconsistent with the Daily Dietary Guidelines among adolescents in Taiwan based on a recent nationwide nutrition survey. The purpose of this study was to apply the ecological model to identify factors affecting dairy product consumption behavior among eighth graders in Taipei, Taiwan. This study included three phases: focus groups, validation of instruments, and questionnaire survey. In the first phase, four focus groups with 20 males and 20 females representing urban and suburban schools were conducted to explore intrapersonal, interpersonal, community, and societal influences in dairy product consumption of eighth graders for developing a valid measurement instrument used in the subsequent quantitative survey. The long-table approach was used for data analysis. It was found that taste preference, restriction of drink choices, availability, perceived benefits, eating occasions, and family influences are important areas to include in an intervention designed for this target group. In the second phase, a self-administered food frequency questionnaire (FFQ) and behavior questionnaire was developed. The 14-item FFQ was validated against repeat 24-hour recalls on 60 eighth graders. The behavior questionnaire was pilot-tested on approximately 200 students and reviewed by an expert panel for content validity. The deattenuated correlation coefficients of 0.52 and 0.87 were obtained for FFQ1 and the average of two recalls and for FFQ2 and the average of two recalls, respectively. Cronbach's a of 0.7~0.9 were reached for all sections of the behavior questionnaire except nutrition knowledge section. In the third phase, questionnaire survey was conducted on a random sample of 1,374 eighth graders (response rate = 91%) and a final sample of 1,090 subjects was used for data analysis. Dairy calcium intake was calculated in SAS based on the Taiwan Nutrient Databases and food labels on the dairy products. Mean dairy calcium intake for all participants measured by a 14-item FFQ was 520 mg/day. More than 50% (278 mg/day) of total dairy calcium intake was solely from 100% cow or goat milk. Two approaches were adopted in data analysis: (1) a behavioral approach using principle components analysis and multiple regression found that facilitating, hindering, interpersonal, and community factors were the four constructs measured in this instrument and significantly predicted dairy calcium intake; (2) a statistical approach using stepwise linear regression and hierarchical linear regression found that convenience, preference for dairy products, self-efficacy, family encouragement, appearance of wholesale stores, and dairy sources from community were significant predictors of dairy calcium intake, accounting for 17.8% of the systematic variance. Implications for interventions targeting eighth graders and their parents as well as for policy-makers were addressed. Significant factors found in this study to be associated with dairy product consumption include the intrapersonal and interpersonal influences, which may be modifiable through interventions; whereas community and societal influences may be changed through policy making or social change and need further studies using different study designs.