A high soluble fibre content will also decrease the cholesterol level in your blood. Adding fibre (such as oats and barley) to a meal will increase the viscosity, causing the contents of the stomach and intestines to empty more slowly. The fibre forms a thin film on the intestinal surface causing the glucose to be absorbed more slowly. When a glucose solution is mixed with large amounts of water-soluble, gel-forming fibre (i.e. guar, beta-glucan) the expected rise in glucose concentration will be reduced.
Soluble dietary fibre probably has the greatest impact on food intake with a high glucose content (such as many snacks) since it has been difficult to show in long-term studies that the addition of dietary fibre has resulted in a better HbA1c. These studies have mainly been done on individuals with Type 2 diabetes. An Italian study of adults with Type 1 diabetes compared a low-fibre diet with a high-fibre diet rich in fruit, legumes and vegetables. Both diets contained exclusively natural foodstuffs. The high-fibre diet resulted in lower blood glucose levels, 0.5% lower HbA1c, and decreased frequency of hypoglycaemia. In a European study on 2,065 adults with Type 1 diabetes, the HbA1c in people whose fibre intake was high was found to be approximately 0.3% lower than for the group with low fibre intake.
Fruit and vegetables are good sources of fibre, but children in the UK eat on average fewer than half of the minimum of five portions recommended per day. A piece of fresh fruit and multi-grain bread can be a good basis if the rest of the meal is made up mainly of "quick-acting" carbohydrates.
Parents can make use of the "fibre effect" by offering a slice of coarse wholemeal bread with some fat (for example margarine or cheese) to their child before other concentrated sugary foods or snacks. The combination of fibre and fat in the meal will help to slow down any rise in the blood glucose level.