De glycaemische index van verschillende graanproducten bij gezonde vrijwilligers.

Rationale: Whole grain foods are thought to be low glycaemic compared to refined flour foods. Since cereal types differ in composition of the type of starch, fibre and protein content, it is expected that the use of different flour types will result in difference in digestion, absorption and consequently glycaemic response.
The glycaemic response of foods, as well as the related glycaemic index (GI), may be predicted based on results obtained from “in vitro digestion’ using the Tiny TIM model, developed by TNO (Zeist, the Netherlands). In order to justify that the in vitro data truly reflect the in vivo data, both tests should be executed and correlations should be calculated.
In the present overall research project the in vitro measurements will be executed by TNO..
The human in vivo experiments are here proposed to be executed at Maastricht University. Accordingly, the current study focuses on the effects of 2 types of ‘Ontbijtkoek’ differing in whole grain flour composition and white bread on the glycaemic response in health human volunteers. Since glycaemic response is known to impact on feelings of hunger and satiety, the subjective feelings of hunger and satiety will be scored in addition.

Objective: To study the effect of 3 different baked foods (white bread and ‘Ontbijtkoek’ containing either rye or teff flour) on blood glucose responses in vivo, to allow for validation of the results obtained in vitro. Additionally, feelings of hunger and satiety in response to these test products will be obtained.

Study design: The study will be executed conform a randomized; cross-over, reference-controlled study design.

Study population: 14 healthy male and female participants, between 18 and 50 years of age, will be recruited.

Intervention: Participants will receive each of 3 test baked test foods (2 types of ‘Ontbijtkoek’ differing in grain flour composition and white bread), randomly on 3 separate test days. In order to avoid differences in product composition, we will use products from a single baked batch. All products will be deep-frozen and used upon daily needs.

Main study parameters/endpoints: The main study parameter is the glucose response curve of all test products. Other important parameters are satiety/hunger scores - based on a subjective rating scale – in response to all test foods.

(1) The ‘Ontbijtkoek’ based on teff yields a lower glycemic response (has a lower GI) than the ‘Ontbijtkoek’ based on rye and both ‘Ontbijtkoeken’ will yield a lower glycemic response than the reference test product, white bread;
(2) The ‘Ontbijtkoek’ based on teff exerts a more positive (or prolonged) effect on measures of hunger and satiety than the ‘Ontbijtkoek’ with a higher glycemic response. Furthermore, it is expected that both types of ‘Ontbijtkoek’ will have more positive effects on measures of hunger and satiety when compared to the reference test product, white bread.
(3) The calculated in vitro glycemic responses the test products are similar to the in vivo measured responses.

Blood samples to measure blood glucose levels will be obtained at -5, 15, 30, 45, 60, 90, 120 and 150 minutes relative to consumption of one of the test products. Participants will be asked to complete a questionnaire to obtain subjective measures of hunger and satiety prior to each blood sampling.

Participants will receive 2 types of ‘Ontbijtkoek’ - differing in grain flour composition: rye or teff - and white bread (reference product) randomly on 3 separate test days.