Dietary intake, B vitamins and health outcomes in the very old : $$b analysis of the Newcastle 85+ study

Abstract

The very old (aged 85 and over) are the fastest growing age group in the UK and most western societies. High incidence of disability and chronic diseases, financial constraints, polypharmacy, hospitalisation, body composition, sensory and gastrointestinal changes place very old adults at increased risk of malnutrition. However, very little is known about the dietary habits and health trajectories in this age group. Further, because one-carbon (1-C) metabolism biomarkers are largely modifiable and have been associated with cognition, cardiovascular disease (CVD) and all-cause mortality, its modulation is of special interest. The overall aim of this PhD thesis was to provide an accurate snapshot of the dietary habits of the very old and examine health trajectories with respect to 1-C metabolism biomarkers in a unique cohort such as the Newcastle 85+ Study. Specifically, we aimed to explore the dietary habits of the very old; to investigate the association between folate, vitamin B12 and its status; and to investigate the cognitive decline and mortality trajectories with respect to 1-C metabolism biomarkers. The Newcastle 85+ Study is a longitudinal population-based study of health trajectories and outcomes over 5 years in 845 eighty-five year olds in North East England. Dietary intake was assessed at baseline on two non-consecutive occasions by a 24 hour Multiple Pass Recall. Baseline red blood cell folate (RBC folate), plasma vitamin B12 and total homocysteine (tHcy) concentrations were determined by immunoassays. Cognitive function was assessed at baseline, 1.5, 3 and 5 years with the standardized mini-mental state examination and a battery of attention tests. Mortality was obtained from the Health and Social Care Information Service, UK. A high percentage of the participants did not meet the dietary reference values for energy, non-starch polysaccharides and several micronutrients. Cereals and cereal products were the top contributors for energy, most macronutrients and several micronutrients, including folate. RBC folate and tHcy were associated with better global cognition at baseline but were not predictive of the rate of decline over 5 years. Higher concentrations of tHcy in all participants and plasma vitamin B12 in women were associated with increased risk of all-cause and cardiovascular mortality. This thesis highlights the paucity of data and uncertainties in this age group. Furthermore, it demonstrates a link between 1-C metabolism biomarkers and age-related diseases.