Bioavailability and Bioactivity of Orange Polyphenols on Gut Health

This study will provide a greater insight into the relationship between orange consumption and health (particularly gut health) and could be used to help with the development of novel food products. Oranges are a rich source of (poly)phenols, and although the advantages of a (poly)phenol-rich diet are well-established, the bioavailability and bioactivity of orange (poly)phenols in the context of human digestion are poorly understood.

Until recently, analysis of biofluids with HPLC-MS revealed relatively simple phenolic profiles. However, with current high resolution (HR)-MS instrumentation detection limits and selectivity have improved greatly and HPLC-HR-MS methodology is now the analytical method of choice. Consequently, the number of phenolics that can be monitored has increased markedly in recent years. A previous study, using validated methodology, identified 65 phenolic compounds in urine collected after ingestion of orange juice.

In the proposed project it is planned to use such analytical methodology for targeted and untargeted metabolomics of flavanone metabolites and colonic catabolites in biofluids collected after consumption of orange juice by ileostomists and subjects with a functioning colon. Metabolomics refers to the measurement of metabolites present within a cell, tissue, or organism resulting from physiological stimulus - in the context of the current study, the stimulus is orange juice consumption. Untargeted metabolomics involves a comprehensive analysis of all measurable substances in a sample of unknown metabolites, and targeted metabolomics denotes the quantification of defined group(s) of metabolites. The particular value of including ileostomists in the study is that analysis of their ileal fluid and urine will provide valuable information on compounds derived from the ingested OJ flavanones, prior to digestion and absorption by the large intestine.

Acute bioavailability feeding study in two groups; ileostomists and healthy adults. The study will take place in the Human Intervention Studies Unit (HISU), at Ulster University, Coleraine Campus. Prior to attending the HISU, participants will be asked to follow a restriction diet for 72 hours before the study and the 24 hours of the study day, which will involve the intake of food containing low levels of (poly)phenols. The participants will be provided with a restriction (low (poly)phenol) meal, which they will consume the evening before the study (at approximately 6 - 7.00pm) and fast until attending the HISU the following morning. This means no food will be taken overnight and no breakfast taken prior to attending the HISU.

Low (poly)phenol foods will be provided to participants on the day of the study, and they will be asked to continue this restriction diet until all samples have been collected. Healthy participants and Ileostomists (N=20) will provide 10 blood samples and 3 urine samples over the study period.