Abstract/Summary

Poor diet contributes to many non-communicable diseases (NCDs). Providing personalised nutrition advice (PNA) via apps could improve diet quality and reduce NCD risk. eNutri uses a food frequency questionnaire (FFQ) to calculate a diet quality score (DQS) and generate automated PNA. This PhD thesis aimed to update and revalidate the eNutri FFQ (eNutri-FFQv3) with older adults (≥65 years) and test the eNutri PNA effectiveness to improve diet quality in two populations facing nutritional transitions, relative to those who did not receive eNutri PNA (control). In a user observation study with older adults (Chapter 2), feedback on the understanding and usability of the eNutri app and FFQ was gathered and used to implement design changes to support engagement. The eNutri-FFQv3 accurately assessed dietary intake relative to a web-based 24-hour recall tool (Chapter 3), confirming eNutri as a valid, reliable tool for assessing UK dietary intake. Focus groups with students at UK universities (Chapter 4) reported several dietary changes when starting university (e.g., reduced diet variety, increased snacking behaviour) which occurred for many reasons, including limited budget and cooking skills. Students were in favour of support to encourage healthier eating. In a 4-week intervention study with students at UK universities (Chapter 5), change in DQS did not differ between the intervention and control group. Conversely, in a 12-week intervention study with patients offered cardiac rehabilitation (Chapter 6), change in DQS was significantly higher (52%) in the intervention versus control group. A recent health event contributing to increased motivation to change diet and engagement with the PNA could explain the differing results in these studies. Overall, eNutri can be used for UK dietary assessment and could help improve diet quality and reduce NCD risk in populations facing nutritional transitions. Future work includes reducing the eNutri FFQ length to improve user retention and adapting the PNA for those with diabetes.