Development and calibration of a modeling tool for the analysis of clinical data in human nutrition
ESAIM: Proceedings and Surveys
This paper addresses the problem of calibrating a compartmental model which describes the postprandial distribution of dietary nitrogen in humans after the ingestion of a protein meal. This type of problem (i.e., a classic inverse problem) requires optimization of an objective function that measures the goodness-of-fit of the model predictions to a given set of experimental data. In our particular case, traditional local, gradient-based optimization methods have failed to arrive at satisfactory
... ive at satisfactory solutions of the inverse problem because of the large number of parameters to be estimated, the high non-linearity of the objective function and the few experimental data accessible in humans. To overcome these limitations, we have developed a calibration method that uses all available information on the system behavior so as to divide the large inverse problem into many smaller sub-problems, on which a variant of the Nelder-Mead (NM) simplex search procedure was proven to be successful. This calibration method makes it possible to obtain solutions that are close to the optimal values of most of the model parameters, even when noisy experimental data are introduced in the objective function. Using these estimated parameters, it is now possible to correctly simulate the temporal evolution of all compartments of the physiological model, which constitutes a useful, explanatory tool to describe the different dynamic processes involved in the metabolic utilization of dietary proteins in humans.