Validity and reliability of stage of change instruments and processes of change to eat fruits and vegetables

The purposes of this study were: (1) to establish validity and reliability of staging instruments for eating adequate servings of fruits and vegetables; (2) to identify processes of change for eating adequate servings of fruits and vegetables; and (3) to find factors associated with inadequate servings of fruits and vegetables. Food intake and psychometric data were obtained from a convenience sample of 294 college students: 80% female and 86% white. To establish outcome validity of several methods used to assign stage of readiness to eat adequate fruits or adequate vegetables, servings from a 3-day food record were calculated. The methods differed only by how fruit and vegetable information was collected, i.e., self-rated intake; a 24-hour recall; or food frequencies of fruits and vegetables for the past week. The criteria for validating post-action stages in all methods were at least 2 servings of fruits or 3 servings of vegetables from a 3-day food record. Average fruit and vegetable servings by all methods distinguished pre- from post-action stages. For fruits, however, the 24-hour was concluded recall showed a higher agreement with the criteria (Cohen's κ = 0.54, p < 0.05)), had good reliability and the highest sensitivity compared to the other two methods. For vegetables, all methods showed only marginal agreement (Cohen's κ < 0.40, p < 0.05). A 24-hour recall was concluded to accurately assess an individual's stage of change in eating fruits, but further research is necessary to develop a good way of assessing vegetable intakes.; By adapting processes of change items from previous studies, 29 items for seven change processes for eating fruits and vegetables (Health Concerns, Self Reevaluation, Social Liberation, Health Commitment/Action, Interpersonal Control, External Reinforcement and Helping Relationships) were developed using confirmatory factor analysis. When subjects' uses of these change processes were compared to their stages of readiness to change for fruit, use of self-reevaluation differed from health commitment/action. For vegetables, use of health commitment, health concern and self-reevaluation processes differed among stages. Health commitment/action along with self-reevaluation of intakes appeared to be important processes used to eat enough fruits and vegetables. The process of health concerns was associated only with eating enough vegetables.; For college students, when less than 2 servings of fruit and less than 3 servings of vegetables were used to indicate inadequate intakes from a 3-day food record, 58% and 82% of respondents reported inadequate intakes of total fruit and fruit without juice, respectively. Fifty-three and 63% reported inadequate intakes of total vegetables and vegetables without fried potatoes, respectively. Inadequate fruit consumption was less prevalent in females, university housing residents, non-smokers, regular exercisers and regular breakfast eaters. Self-efficacy was inversely associated with inadequate intakes of both fruits and vegetables. Inadequate fruit intake was positively associated with higher discretionary fat intakes, but inadequate vegetable intake was not. Therefore, eating fruit was more associated with other positive health behaviors than was eating vegetables. When fruit juice and fried potatoes were excluded, fruit and vegetable intakes were positively associated with each other.