Glucose Kinetics After Wheat and Rye Breads

Determination of Glucose Kinetics After Wheat and Rye Breads to Understand Their Physiological Effects

Certain functional properties of cereal products, e.g. their postprandial glucose and insulin responses, have been characterized as steps towards obtaining a greater understanding of their beneficial health effects. A low-glycemic index diet results in decreased postprandial insulin and glucose responses, which is thought to be beneficial for insulin and glucose metabolism. In healthy subjects, it has been shown that rye breads (RBs) produce a lower postprandial insulin response compared with refined wheat breads (RWB) despite similar glucose responses. Juntunen et al. (2003) suggested that the difference in the structural characteristics between rye and wheat breads is a possible explanatory mechanism. However, the underlying mechanism of this discrepancy between insulin and glucose responses to rye bread, the so-called "rye factor" (RF), is still largely unknown. Faster starch digestibility and higher postprandial insulin responses for RWB compared with RBs may indicate faster intestinal glucose absorption and faster glucose disappearance respectively. Therefore our hypothesis is that despite having similar glucose responses, RWB has faster turn over (kinetics) compared with RBs. The present study is aiming to apply an experimental set up which can comprehend the hypothetical differences in RWB and RBs kinetics.

The human subjects after an overnight fasting 10-12 hours are coming to the clinic. On arrival, catheters are inserted into a forearm vein of each arm for blood sampling and isotope infusion, respectively. A primed followed by a constant-rate infusion of [6,6-2H2] glucose are administered. The enrichment of [6,6-2H2] glucose in the blood is then measured at different time points after the breakfast. The glucose kinetics can be calculated from this.

The study was carried out using a crossover design with a three-week washout period. The participants stayed overnight at the facility and had one out of two types of breakfast in the morning.

A breakfast consisting of whole slices of wholemeal rye bread containing 50 g of available carbohydrates. The breakfast additionally included 250 mL water and 50 g of cucumber.

A breakfast consisting of whole slices of refined wheat bread containing 50 g of available carbohydrates. The breakfast additionally included 250 mL water and 50 g of cucumber.

Glucose kinetics are investigated after ingestions of two different kinds of bread based breakfasts in order to see how the body responds to the different breads.

Inclusion Criteria: Males 18-40 years with BMI 22-25.5 kg/m2 Exclusion Criteria: A family history of diabetes mellitus, regular use of nicotine, recurrent extensive exercise, regular intake of medication or food intolerances. The subjects had to be free from illnesses for one month prior to the study.