Applicability of the stages of change model for analyzing fruit and vegetable intake in relation to urinary potassium excretion: Baseline results from the High-Risk and Population Strategy for Occupational Health Promotion (HIPOP-OHP) study

The Stages of Change model evaluates and conceptualizes attempts to alter particular behavior patterns. To investigate the validity of this model for assessing fruit and vegetable intake, we examined the association between the stage of change in fruit and vegetable intake and urinary potassium excretion. The data were from baseline surveys taken in 1999 and 2000 from the High-Risk and Population Strategy for Occupational Health Promotion (HIPOP-OHP) study in Japan. This was a non-randomized control trial at 12 worksites in Japan and aimed to decrease cardiovascular risk factors. Cross-sectional analysis was performed using data from 6,774 participants (5,364 men and 1,410 women). We used three categories of the model: precontemplation or contemplation (P/C), indicating no commitment to change; preparation (P), indicating readiness to change behavior but not actually doing so; and action or maintenance (A/M), indicating an actual change in behavior. Urinary potassium excretion was estimated from the potassium and creatinine concentrations in spot urine samples. Multivariate analysis indicated that urinary potassium excretion in the A/M stage was 1.65 mmol/day more than in the P stage, and 1.44 mmol/day more than in the P/C stage for men (p<0.05, respectively). For women, urinary potassium excretion in the A/M stage was 1.26 mmol/day more than in the P/C stage (p< 0.05) and 1.04 mmol/day more than in the P stage, although the latter result lacked statistical significance (p=0.08). This study supports the potential value of the Stages of Change model for increasing fruit and vegetable intake in the design of dietary intervention programs.