Year

2005

Degree Name

Doctor of Philosophy

Department

Department of Biomedical Science; Smart Foods Centre - Faculty of Health & Behavioural Sciences

Abstract

Coronary heart disease (CHD) is the single largest cause of death and disability in most modern western societies and poor diet is a significant risk factor in the pathogenesis of this disease. Despite significant advances in the treatment of CHD, effective primary prevention approaches remain elusive largely due to the difficulty of sustaining significant and long term dietary changes. In this doctoral program, the hypothesis that the use of functional foods is an effective strategy in the primary prevention of this lifestyle disease was examined. Methodological approaches grounded in the field of nutrition science and behavioural psychology, incorporating both quantitative and qualitative studies were used. Results of a dietary trial in 25 patients, reflective of �free-living� clinical practice conditions, found that a functional food-led intervention using plant sterol enriched margarine was an effective approach in the management of hypercholesterolemia. Sixty percent of subjects counselled on the inclusion of 25g per day of plant sterols achieved (greater than) 15% reduction in total serum cholesterol, compared to none receiving standard dietary advice. In another dietary trial that was a randomised placebo controlled dietary intervention with parallel groups, 86 overweight, but otherwise healthy, subjects where asked to choose at least eight serves per day from a selection of either long chain omega-3 fatty acid (LCn-3) enriched foods (~125 mg LCn-3 per serve) or matched control foods. After six-months, participants were able to increase their dietary LCn-3 intake 4-fold (to ~1200 mg/day) and this was confirmed by a corresponding increase in the erythrocyte LCn-3 levels by 20%. This has implications for CHD reduction given the importance of dietary LCn-3. Consumer and social research also suggest that functional foods can have an important role in public health. The Theory of Planned Behaviour (TPB) was used as a theoretical framework for a study examining prediction of intention to use n-3 enriched functional foods, using a purpose designed questionnaire and follow up of recorded intake. Regression analysis was able to show that the model was a significant predictor of intention (R2 = 0.725, P (less than) 0.001) and to a lesser extent behaviour (R(superscript 2) = 0.298, P (less than) 0.001). Attitude was significantly positively associated with intention, whereas subjective norms and control beliefs were not. These results imply that the best prospects for modifying behaviour are likely to come through a change in attitude. Beliefs and attitudes of key influencers are a significant determinant of consumer attitude. Semi-structured interviews with stakeholders (e.g. nutrition professionals, scientists, regulators, media personnel and food industry representatives) revealed there are a number of areas of agreement in their attitudes towards functional foods, including the need for safety, taste, bioactivity and extensive evidence for claims. Divergent views were expressed in relation to the regulation of health claims and the levels of evidence required substantiating these claims. A strong feature of the areas of disagreement was lack of clear scientific evidence available to form opinions, and stakeholders often relied on pre-existing ideology. These differing views may impact negatively on consumer attitude to the use of functional foods. In conclusion, analysis of clinical and consumer research suggests that use of functional foods can be an effective preventative health strategy for CHD as long as the maintenance of positive consumer confidence can be achieved.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.