Internal locus of control and social support associated with some dietary changes by elderly participants in a diet intervention trial.

OBJECTIVE: Measure relationships of locus of control and social support to diet changes in an intervention trial. DESIGN: Participants in the Polyp Prevention Trial (PPT) completed Multidimensional Health Locus of Control (MHLC) and Norbeck Social Support Questionnaires (NSSQ) and modified Block food frequency questionnaires. Data were collected at baseline and 1 year later. SUBJECTS/SETTING: A convenience sample of PPT intervention (N = 68) and control (n = 43) participants at 1 clinical center participated in this ancillary study. MAIN OUTCOME MEASURES: Mean daily dietary intakes after 1 year were compared with baseline values. Intervention participants' scores for MHLC internal locus of control and NSSQ total functional network were correlated with diet changes. STATISTICAL ANALYSES PERFORMED: Group percentages were compared using the Fisher exact test; means were compared by t test. RESULTS: Groups were comparable in demographics, baseline diet, and scores for internal locus of control and total functional network. Intervention group participants made greater diet changes than control participants in intake of fat (-27 g vs -8 g), fat as a percentage of kilocalories (-8% vs -2%), fiber as grams per 1,000 kcal (7 g vs 0.3 g), and daily fruit/vegetable servings (2.0 vs 0.2). Pearson correlations of diet changes with internal locus of control scores (all P > .05) were fat grams, r = 0.031; fat as percentage of kilocalories, r = 0.023; fiber grams per 1,000 kcal; r = 0.230; and fruit/vegetable servings, r = 0.186. Correlations with total functional network scores were: fat grams, r = 0.022 (P > .05); fat as percentage of kilocalories, r = -0.108 (P > .05); fiber grams per 1,000 kcal, r = 0.276, P < .05; and daily fruit/vegetable servings, r = 0.326, P < .05. APPLICATIONS/CONCLUSIONS: Intensive and skillful dietary intervention can succeed whether or not clients bring strong internal locus of control or social support to the diet change program.