Calcium Intake Pattern among Japanese Women across Five Stages of Health Behavior Change

BACKGROUND: The transtheoretical model (TTM) of health behavior change is one of the most promising approaches for health professionals to help individuals change their behaviors. Few studies have assessed calcium intake using the model on Asian women. This study aims at clarifying characteristics of each behavioral stage among Japanese women and providing clues to increase calcium intake to prevent osteoporosis. METHODS: A cross-sectional survey was conducted from September through November, 2005 using self-administered questionnaires. A total of 226 participants in an osteoporosis screening program were invited to take part in the study, and 150 women were enrolled. RESULTS: Adjusted means of total dietary calcium were positively significantly associated with successive stages (p<0.001). The proportion of calcium intake from plants and fish was higher in the precontemplation, contemplation, and preparation stages compared with the action and maintenance stages (p=0.038). Concomitantly, the plants and fish food group contributed 46.7% of total dietary calcium, while 32.4% was derived from milk and dairy food, and 20.9% from other foods. The correlation coefficient (95% confidence interval) between the proportion of calcium obtained from plants and fish and the proportion of fat energy was -0.22 (-0.37, -0.06). CONCLUSIONS: The proportion of calcium intake from plants and fish was higher among women in the lower stages compared with higher stages. Given the higher prevalence of lactose intolerance, it would seem plausible to recommend lower-stage women be educated and encouraged to derive more calcium from plants and fish diets as a means to prevent osteoporosis.