Q: "Not long after reading your article on GI, I noticed a high-fibre white bread with the nutritional claim of 'Lo-GI'. It claimed to have three times the fibre of white bread. Can you tell me how they manage to increase the fibre so much without including bran layers (is it soluble fibre?) and how they manage to then classify the bread as being low-GI (I'm assuming 'lo' means low). This is a Baker's Delight product."
A: Dietitian Amanda Johnson explains:
"Most varieties of white bread do have a high GI value and are low in fibre; however, there are a range of white breads now appearing on the market with added cereal or vegetable fibre; some of these may have a lower GI than standard white bread.
The Baker's Delight Lo-GI bread recipe, for example, involves the addition of resistant starch, soy flour and vegetable gum (guar gum) to actively reduce the GI and increase the fibre. The fibre content is 8.3g per 80g portion (2 slices) and, according to the manufacturers, the bread has a GI of 52.
Whole grain varieties of bread are also a good choice, and typically have a GI in the range of 46-53.
Glycaemic index (GI) is the measure of the rate at which glucose is absorbed into the bloodstream after eating a specific food. It is determined by comparing the blood glucose response from a particular food, to a reference food (usually glucose, which is given a value of 100). Foods that break down quickly will raise blood glucose quickly, and are given high GI values. Foods that break down slowly will raise blood glucose slowly, and are given low GI values.
A food is said to have a low GI if it has a value of less than 55, a medium GI if it has a value of 56 to 69, and a high GI if it has a value of over 70."
You can find more information on the glycaemic index of different foods at Glycaemic Index / Database.