Purpose. This study is a mediation analysis of three Social Cognitive Theory (SCT) constructs – knowledge, self-efficacy, and self-regulation to determine their influence on changes in consumption of fruits, vegetables, low-fat dairy products, and high fat/high sodium foods (DASH-4-Teens Diet) in adolescents with hypertension.
Methods. Fifty-seven participants with prehypertension or stage 1 hypertension were stratified by gender and race (Caucasian or African American) and randomized to either usual care (n=28), or the DASH-4-Teens (n=29) nutrition intervention. Participants in the usual care group received counseling on established nutrition guidelines from the National High Blood Pressure Education Program to lower their blood pressure. Participants in the DASH-4-Teens group were encouraged to follow the DASH diet, and had 1 individualized counseling session with a Registered Dietitian, 8 weekly and 2 biweekly telephone contacts, and 4 biweekly mailings on behavioral strategies that complement the SCT to lower blood pressure. Diet, knowledge, self-efficacy, and self-regulation were measured at baseline and post-intervention in both groups.
Results. The intervention was successful in significantly increasing knowledge (P < 0.01), self-efficacy (P < 0.01), and self-regulation (P < 0.01). Self-efficacy was the predominant mediator in changes in fruit intake (P < 0.05). Self-regulation was the predominant mediator in changes in low-fat dairy intake (P < 0.05). None of the psychosocial factors in this study were able to significantly explain the increase in vegetable intake or the decrease in DASH-unfriendly foods.
Conclusion. A nutrition intervention based on the DASH diet and SCT has the ability to mediate changes in self-efficacy and self-regulation which in turn mediate changes in fruit and low-fat dairy, respectively.