The Effect of Dietary Fiber-enriched Bread on Gastric Emptying and Postprandial Glucose Levels

The rate of gastric emptying is related to small intestinal motility and absorption of carbohydrates, and it is one of the major determinants of postprandial glycemia. A slower rate of gastric emptying will thus result in a less pronounced rise in blood glucose. Especially in diabetes care, reduced gastric emptying is desirable because of its effect on the rise of postprandial blood glucose, which again highly influences the overall glycemic control.

Bread is one of the most eaten food items in Central- and Northern Europe, being one of the major sources of dietary carbohydrate intake. In addition, bread often contains a diverse range of dietary fiber. The effect on gastric emptying and the amount of dietary carbohydrates absorbed in the small intestine depends on the overall meal composition, the degree of processing, and the type of dietary fiber, e.g., viscous or non-viscous. The oat-derived dietary fiber beta-glucan may have favorable properties in this regard as adding beta-glucan to a meal has been shown to slow down the rate of gastric emptying. However, studies investigating the effect of beta-glucan on gastric emptying are scarce.

For assessment of gastric emptying, scintigraphy is seen as the "gold standard" as the method readily can discriminate between gastric emptying and absorption of glucose in the small intestine. However, this method is not often used due to its invasive nature and radiation. High-resolution real-time ultrasonography is now the most preferred method and regarded as a new "gold standard", proving good inter- and intra-observer agreement. Compared to scintigraphy, ultrasound is a safe and non-invasive procedure widely available in clinical settings.

Objectives

To establish whether a wheat bread with an optimized content of beta-glucan has a different effect on gastric emptying, satiety, and postprandial glycemia compared to control bread.