Design and evaluation of a nutritionally adequate diet for healthy ageing in older UK adults: The Healthy Ageing DIet (HADI) Study

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The UK population is ageing rapidly. By 2025, the number of adults aged 65 years will double to reach 18.5 million, with fastest growth expected among those 85 years1. A key public health challenge is to identify effective solutions to reduce disability and morbidity and extend the health span of UK citizens2. In this regard, adequate nutrition can protect against age-related physical and cognitive function decline3,4 and prevent chronic disease such as cardiovascular disease5. The Eatwell Guide provides advice on food groups which supply the required reference nutrient intake (RNI) and promote overall UK population health with low environmental impacts6. However, ageing is associated with numerous physiological changes e.g. loss of olfactory function and taste7, altered inflammatory and immune responses8, altered body composition9, delayed gastric emptying10 disrupted appetite regulation11, leading to altered food preferences12 and decreased nutrient bioavailability13 that predispose older adults to nutrient deficiency14. Lovegrove et al14, recently reported strong evidence to support an increased RNI for protein, calcium, folate and B12 among those aged 65 years in the UK. Hence, older adults have nutritional needs that differ from those of the younger adults and which have not yet been fully considered in UK dietary guidelines. Other nutrients of concern during ageing include suboptimal intakes of potassium, iron, zinc, vitamin A, vitamin C, vitamin E, vitamin K, vitamin B6 and vitamin D13 and excess saturated fat, sugar and sodium15. There is a critical need to define nutritionally adequate dietary recommendations for optimal health and well-being in later life and inform targeted agri-food innovations to help UK citizens aged 65 years meet their nutritional needs. The proposed PhD project aims to address these gaps by: (i) combining evidence review, state of the art diet modelling techniques and stakeholder engagement to design a Healthy Ageing DIet (HADI) for older UK adults; and, (ii) evaluating the impact of HADI on nutritional intake, nutritional status and measures of healthy ageing. Research questions1. What are the optimal food combinations required to achieve nutritional adequacy in older adults and feasible to implement with minimal deviation from the current UK diet? We hypothesise that it is feasible to define acceptable food combinations to optimally meet the nutritional needs of older UK adults2. What is the association between adherence to an optimised Healthy Ageing DIet (HADI) and nutritional status in older UK adults? We hypothesise that HADI will be associated with adequate intake and status of key nutrients of concern 3. How does an optimised HADI relate to changes in physical and cognitive performance and chronic disease risk? We hypothesise that greater HADI adherence will be associated with slower cognitive and functional decline and reduced risk of cardiovascular disease Main objectives are to:1. Complete a systematic review on health impact of undernutrition in older adults (year 1)2. Apply diet optimisation modelling using national food consumption data to define the minimum amount of dietary change to food group proportions represented in the Eatwell Guide to meet nutritional requirements for adults 65 years (year 1-2)3. Use the models to determine 'problem' nutrients requiring diet fortification to meet the nutritional needs of older adults (year 2)4. Conduct qualitative research with older consumers and agri-food industry stakeholders to define acceptable foods that would be feasible for targeted nutrient fortification and product innovation (year 2)5. Construct HADI score to determine adherence to an optimised healthy diet for 65 years (year 3)6. Conduct longitudinal data analysis in nationally representative UK ageing cohorts to determine relations between HADI, nutritional status and healthy ageing (year 3-4)