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FeatureThe Challenge of Behaviour ChangeFinding out how to improve calcium levels in women provides an insight into the nature of behavioural change. Caroline Horwath There has been a great deal of research regarding the importance of calcium in safeguarding bone health. Research into boosting boost calcium intake, particularly for women, has called upon other approaches to encouraging behavioural change. In New Zealand and most other Western societies, the majority of dietary calcium is obtained from milk products. Median calcium intakes among New Zealand women fall well below current recommendations. In women aged between 25 and 44, the median calicium intake is 631mg/day, compared to a recommended 800mg/day; in the 65+ bracket, it falls to 481mg/day, less than half the recommended 1,000mg/day. Several surveys have shown a high proportion of women to have low calcium intakes. Men's calcium intakes tend, on average, to be around 200mg/day higher. For most people, it is possible to achieve a calcium intake of 1,000mg/day through regular food intake without the use of supplements. Studies have shown that the inclusion of low-fat milk products ensures that dietary fat intake and blood cholesterol levels need not be adversely affected. An added bonus of obtaining calcium from foods such as milk products is the profound improvement in intakes of other essential nutrients, particularly magnesium, potassium and B vitamins. The challenge for nutritionists is to improve women's intake of milk products. However, we have little research on the mechanisms for successfully changing eating habits and for maintaining eating behaviour changes. What are the barriers to achieving adequate calcium intakes among women? How can we improve milk product consumption? As a first step in addressing these questions, we undertook qualitative research with those young and older women who, in our dietary intake surveys, had calcium intakes below two-thirds of the recommended level. We conducted detailed interviews to examine women's perceptions of the likely effects of increasing their intake of milk products, and their reasons for cutting down consumption. In a nutshell, what we found was that three-quarters of older women believed that consuming more milk products would actually be bad for them. They were concerned with adverse effects on conditions such as diabetes, high blood cholesterol or blood pressure. Some 15-20% of all women said that they had been advised by doctors to eliminate milk or other milk products from their diet, usually for inappropriate reasons -- these included headaches, sinus problems, reducing fat or cholesterol intakes, mucous production or for the management of kidney, pancreatic, heart or diabetes problems. Young women were more likely to believe in the health benefits of milk products. However, in this age group, fear of weight gain was particularly important. A dislike of milk was also mentioned as an important barrier by around one-third of women. This preliminary research gave us some clues as to the barriers to milk product consumption. We then felt that a stronger theoretical basis was required to improve the success of efforts to raise population calcium intakes. Psychologists at the University of Rhode Island, US, have developed a model for understanding health behaviour change. The model descibes the adoption of a new behaviour (or cessation of an existing behaviour) as movement through a series of stages. It also describes processes or techniques people use as they change their own behaviour patterns. Intervention programs based on the model are now well established as the most effective means of helping people quit smoking, and there is also support for the model across a wide range of other behaviours. It's a giant leap to take a model that's been developed for smoking cessation and use it to understand eating behaviour change. But that is what Pauline Gulliver and I have been working on here in the Deptartment of Human Nutrition at the University of Otago -- the application of the Transtheoretical Model (TM), or Stage of Change Model, to the goal of improving milk product consumption in women. The research is being funded by the New Zealand Dairy Board. Five-Stage ProcessWhether giving up an undesirable behaviour such as smoking, or adopting a healthy behaviour such as exercising, people typically move through five stages. The stages are:
Movement through the stages is assumed to be cyclical rather than linear. Relapse and subsequent recycling through the stages is common. Most people require several attempts before successfully overcoming a problem behaviour or adopting a new healthy behaviour. According to this model, when we intervene to change people's eating habits, we need to speak the language of the stage they are in. Typically only 10-15% of the population is prepared to take action in making a lifestyle change, and yet many of our nutrition education programs are most suited to those who are already somewhat amenable to change. Process of Change ImportantIn addition to classification of a person's motivational readiness to consider a behaviour change, the model also includes the concepts of processes, decisional balance (DB) and self-efficacy (SE). Most of the early studies applying the model to behaviours other than smoking examined only the stage of change. However, the processes of change form the basis for intervention -- they are the common strategies or techniques used to change behaviour. For example, the process known by psychologists as "counter-conditioning" involves substituting a more healthy behaviour in place of a less healthy one. "Consciousness raising" involves gaining an awareness of the problem. Successful change depends on doing the right things (processes) at the right times (stages). Stage-matched interventions -- interventions designed specifically to suit people at specific stages of readiness to change -- are far more effective than traditional intervention programs. Without going into detail about the particular processes, those which involve gaining insight and understanding are most effective in the early stages, while behavioural strategies are most effective in the later stages. Decisional balance and self-efficacy are important aspects of the model which enable us to understand how the meaning of change alters as one moves through the stages. During the earlier stages, change is conceptualised as cognitive (moving from no intention of changing to considering it). Those in preparation plan change in the near future, and those in action and maintenance stages have changed the behaviour of interest. Decisional balance is the perception of the pros and cons of adopting the new behaviour. Self-efficacy, or confidence to perform a behaviour in a specific situation, is a powerful predictor of behaviour change. The purpose of our research was to develop and validate questionnaires to measure each of these concepts for milk product consumption. For some of the concepts, moving from an addictive behaviour (smoking) to a positive dietary behaviour was a real challenge. We wanted to test whether the relationships found between these different aspects of the model for smoking cessation would also be found for a positive dietary behaviour, such as meeting recommendations for milk product intake. We looked at women's readiness to follow two recommended intake goals: 2-3 servings/day and a higher goal of 4 or more servings per day. For the sake of simplicity, I'll just mention results for the goal of 2-3 servings per day. Two random population surveys of women in Dunedin and Christchurch were conducted. Questionnaires were tested in the first smaller survey, then refined in the second survey. Subjects were randomly selected from the electoral rolls, and a 14-page mail survey was sent to each subject to measure processes, DB & SE, calcium intake and demographics. Calcium intake was estimated using a validated food-frequency questionnaire. Stage of readiness to change was assessed in a follow-up phone interview. Eighty percent of women completed the mail questionnaire, and 80% of those could be contacted by phone to determine their stage of readiness to change. As has been found with research on other behaviours, most subjects fell into either precontemplation or maintenance. As hypothesized, calcium intakes increased progressively across the stages, with mean intakes in action and maintenance meeting the recommended intake of 800 mg/day. We also validated questionnaires to measure women's perceptions of the pros and cons of increasing their milk product consumption. Questionnaire items representing the pros of change emphasised benefits to self such as health benefits and self-approval. Items representing the cons of change emphasised personal concerns with weight gain and extra calories, and potential adverse effects on health. The pattern of change in pros and cons across the stages followed a similar pattern to that observed with other health behaviours, providing evidence of the validity of the questionnaires. The increase in pros scores between subjects assigned to precontemplation and action corresponds to a large effect size. This reflects the difficulty in moving from precontemplation to action. The smaller decrease in the cons of change across the stages is remarkably similar to findings observed for other health behaviours. A significant reduction in cons is required in order for change to occur, however this difference doesn't have to be as large. This research suggests that when designing stage-matched interventions, nutrition educators and counsellors need to emphasize the benefits of change. A huge shift in the perception of the pros of change is needed. Advertising the benefits of lower fat milk products, improved nutrition education for doctors and other health professionals, and more appropriate advice on weight control issues, may all help to increase the perceived benefits of change. We also found that women's confidence to meet the goal of having 2-3 servings of milk products per day increases dramatically across the stages. In order to improve women's milk product consumption, we need to build self-efficacy, raise perceptions of the benefits of change, and reduce the cons of change. These results suggest that stage-matched intervention programs may offer an effective means of improving women's calcium intakes, and also highlight the potential usefulness of this model for promoting other changes in eating behaviour. Dr Caroline Horwath is the Senior Lecturer in Human Nutrition at the University of Otago. |
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