This thesis describes the application of compartmental modelling techniques to data from human intervention studies with the objective of studying the absorption and metabolism of minerals (iron, copper, calcium) and vitamins (folate, carotenoids, riboflavin) labelled with stable isotopes. Compartmental modelling is a mathematical tool that uses differential equations to describe a dynamic process, such as nutrient metabolism, by adjusting the parameters of the equations until the model is a good fit to the real experimental data. A single compartment model was developed that can be used to estimate the quantity of absorbed (unlabelled) iron from a test drink containing a minimum of 10mg iron. Studies on copper demonstrated that approximately 74% of the absorbed dose is sequestered by the liver on “first-pass” and that large quantities of copper (2.4mg/d) are lost via the bile. Data from a calcium intervention trial was evaluated using a multi-compartment model and indicated that a moderately high salt intake (11.2g/d) was associated with a significantly negative bone calcium balance with a high calcium (1284mg/d) compared to a low calcium (518mg/d) diet (P=0.024). Modelling the initial metabolism of an absorbed dose of 13C-labelled folic acid resulted in the finding that it is not metabolised in the mucosal cells but (probably) in the liver. The absorptive efficiency of carotenoids was investigated by isolating the triglyceride rich lipoprotein fraction in plasma and a simple model was used to estimate β-carotene and lutein bioavailability. Results from the first stable isotope labelled riboflavin study indicated that the bioavailability of riboflavin from spinach (60±30%) was not significantly different to the bioavailability of riboflavin derived from milk (67±21%). The thesis has shown how compartmental modelling, in conjunction with stable isotope labelling, can reveal new insights into human mineral and vitamin metabolism, especially in the study of nutrient bioavailability.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:569333 |
| Date | January 2010 |
| Creators | Dainty, Jack Richard |
| Publisher | University of East Anglia |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ueaeprints.uea.ac.uk/10612/ |
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