Applying metabolic profiling as an objective dietary assessment method for personalised nutrition

Abstract

Background: Non-communicable diseases (NCDs) are the main causes of mortality and morbidity, globally and in the UK. Dietary changes have shown positive impacts on the risk factors associated with NCDs. However, there are concerns about the effectiveness of general dietary advice. Personalised dietary advice is proposed as an effective approach. Recent advances have been made in the development of a new methodology that uses metabolic profiling and multivariate mathematical modelling to provide objective, accurate information about an individual's dietary patterns based on urine composition, which can be used to design personalised nutritional interventions. The aim of the thesis is to facilitate translating the metabolic profiling strategy into clinic by investigating the concordance between a metabolic profiling strategy and traditional dietary assessment methods, building a new mathematical model particularly for people at risk of cardiovascular disease (CVD), developing a dietary protocol to provide personalised dietary advice, and assessing the feasibility of applying metabolic profiling in a clinical setting for personalised dietary advice. Methods: Data from a previous observational study collected fasting urine samples with a matching 24-hour dietary recall once a week over a 6-month period was used to investigate the concordance between metabolic profiling and traditional methods on long term dietary assessment. In a highly controlled environment, a randomised inpatient crossover clinical trial was conducted to assess the impact of dietary interventions on urinary metabolic profiles and clinical parameters in order to build a new mathematical model, particularly for people at risk of CVD. A dietary protocol was developed by adopting the revised British Dietetic Association (BDA) model and process to facilitate personalised dietary advice that was in alignment with public and patient involvement (PPI) which has been conducted through various activities (focus group meetings, individual interviews, dietary counselling sessions, and surveys) with dietitians and participants at risk of CVD to gain their perspectives regarding the overall research project and particularly the new method of dietary assessment in the clinical setting in order to maximise the applicability and efficacy of the provided dietary intervention in the clinical trial. A randomised pilot clinical trial was conducted to assess the feasibility of providing metabolically personalised dietary advice in clinic to help people at risk of CVD to change their dietary habits within their own environment using the new mathematical model and dietary protocol. Results: Findings from the observational study showed poor agreement between the DASH score and the urinary dietary patterns score in overall data and subgroups. There were discrepancies in the concordance between the classifications of the dietary adherence of the urinary biomarkers and their related dietary intakes. In the randomised inpatient trial, significant differences in the dietary intakes between the interventions (Diet1 vs. Diet2) were reflected in the urinary metabolic profiles of participants; the RM-MCCV PLS-DA model shows clear separation in the global urinary metabolic profiles of the two dietary patterns. A robust model has been developed using the global urinary metabolic profile associated with distinct dietary 2 patterns. A dietary protocol has been developed to facilitate personalised dietary counselling, and this was in alignment with PPI which has positively impacted the dietary intervention design, researchers, dietitians, and participants at risk of CVD who involved in PPI activities. Finally, the randomised pilot clinical trial shows the feasibility of using metabolic profiling in clinic to personalise dietary advice for people at risk of CVD. Conclusion: A metabolic profiling strategy is promising and feasible and can objectively provide information about dietary adherence. In addition, it can be applied as a complementary method along with traditional dietary assessment methods to obtain further details about individual diets. However, some considerations need to be taken when applying urinary metabolic profiles to personalised nutrition, and further research is needed to enhance the application of urinary metabolic profiles.