Assessment of Mediterranean diet scores in older adults

Abstract

The United Kingdom is experiencing an ageing population. Currently one sixth of the UK’s population is aged over 65 years and this is estimated to rise to one quarter by 2050. There is considerable inter-individual variation in human lifespan and much of this variation appears to be due to non-genetic factors, including lifestyle. Both observational and intervention studies indicate that adherence to a Mediterranean dietary pattern is associated with increased lifespan and reduced risk of age-related disease. The LiveWell Programme was established to develop and pilot lifestyle-based interventions (including promoting a Mediterranean diet) to enhance healthy ageing, which could be delivered to individuals in the retirement transition. The aim of this PhD was to test age-appropriate dietary assessment methods suitable for measuring change in adherence to a Mediterranean diet, as a consequence of lifestyle-based interventions. Six different approaches for estimating Mediterranean diet scores (MDS) were applied to dietary data from the Mediterranean Diet in Northern Ireland (MEDDINI) intervention study. Based on the number of assumptions and modifications that were made to calculate the scores, the percentage change in diet between intervention groups and the coefficient of variation from baseline to follow up, the relative Mediterranean diet score (rMED) was identified as the most suitable score for testing the efficacy of intervention studies in a UK context. The next stage of the work was to investigate the utility of INTAKE24, an online 24 hour recall, as a method for assessing the diet of retirement-age adults. INTAKE24 is a self-completed dietary assessment tool which was developed originally for use with young people. This was the first time that this tool was used with older people and so it was essential to undertake user-testing and estimation of relative validation. The system usability was rated as above average by the majority of users. Of the food items recorded in INTAKE24, 87% of the foods recorded during user-testing and 84% of the food items recorded during relative validation, either exactly or approximately matched foods iii recorded in a comparable interviewer-led 24 hour recall. No significant differences in nutrient intakes or adherence to the Mediterranean diet (assessed by the rMED) were found between the two dietary assessment methods for either the user-testing or the relative validation study. In conclusion, INTAKE24 was well-received and assessed the diets of older adults well when compared with a conventional approach. However, further modifications of INTAKE24 (detailed within my thesis) would improve the usability and accuracy of the system for future studies involving older adults. In addition, the rMED method of scoring adherence to the Mediterranean dietary pattern is compatible with data collected using INTAKE24 and appears suitable for use in future dietary intervention studies with adults in the retirement transition.