| Popis: |
As consumers become aware of the role functional foods can play in their personal health, the differentiating aspects of such functional foods need to be determined. One such aspect is the information provided on the bioavailability of the active ingredients responsible for functionality, which plays a role in marketing and the regulatory process. Regulators are starting to develop guidelines and criteria that take bioavailability into account. Although bioavailability is not a new term for foods, the many parameters which determine bioavailability in a food context are not understood in full. On one hand, bioavailability is controlled by the active ingredient itself, as determined by its physicochemical characteristics and the response of the human physiology upon exposure. Understanding the basic principles and physiology is, however, too simple an approach. On the other hand, for food-specific processing, the food matrix itself and the response of human physiology towards a food product and meal intake also play a role. They determine to a great extent the gastrointestinal milieu from which the active ingredient needs to be absorbed. This interplay of ingredient, matrix, gastrointestinal condition and body response, including post-absorption, has to be taken into account in determining bioavailability of a functional ingredient or in developing new functional food products. Thus the models that predict bioavailability based on physicochemical parameters should be used cautiously as other factors can be dominant. Within foods there is a need to expand these predictive models into the relevant chemical space. To test these predictions or food concepts, in vitro models are suitable as long as they reflect the actual intestinal conditions in the fasted or fed state. In this area considerable progress has been made, resulting in proper biorelevant models. One aspect, which is still little understood, is that of meal composition and meal conditions (e.g. is the active ingredient taken with the meal, or before or after) on bioavailability. No relevant standards have been agreed on experimental conditions, nor are all critical limits known for the physiology triggers and their inter- and intra-individual variations. To guide the functional foods researcher in this complex area, examples are given and a simple logic scheme is provided as a start in developing a bioavailability research strategy. |
