Food-Based Biomarkers: From Discovery to Use

The impact of diet on health and disease is well-documented in the literature. However, traditional dietary assessment methods are subjective and are prone to errors including misreporting and inaccuracies regarding portion size estimations. Food intake biomarkers offer a more objective measurement of intake and have demonstrated important applications in nutrition research. Currently, there are promising candidate biomarkers of various foods, but more work is required to identify a broader range of biomarkers, assess their validity and demonstrate their utility. This thesis aimed to identify and assess the dose-response of food intake biomarkers for green vegetables, examine the changes in the metabolic profile following a personalised intervention, and determine the influence of geographical origin on the blueberry metabolome.
Biomarkers of green bean and green leafy vegetable intake were identified in an acute feeding study through nuclear magnetic resonance (1H-NMR) and liquid chromatography-mass spectrometry (LC-MS) methods. The dose-response of these biomarkers was determined in a further intervention study where participants consumed three different portion sizes of the foods. A panel of 12 green beans biomarkers could differentiate between low and high consumers with good accuracy. Additionally, a combined model of two green leafy vegetable biomarkers demonstrated an ability to predict low intakes. The PAD-Q intervention study investigated the effectiveness of personalised dietary advice to improve diet quality. Following the 6-month intervention, increases in biomarkers of fish and fruit intake were observed in individuals receiving personalised advice. In addition, an untargeted metabolomic analysis revealed that the metabolomic profile of blueberries from three different geographical origins were not distinctly different.
In conclusion, this thesis progressed the area of food intake biomarkers by identifying dose-responsive biomarkers for green bean and green leafy vegetable intake. In addition, the current work showed the potential of including food intake biomarkers in personalised nutrition interventions. Furthermore, this thesis contributed to the field of food metabolomics by addressing the influence of geographical origin on the metabolomic profile of blueberries.