Does type of bread ingested for breakfast contribute to lowering of glycaemic index?

Abstract

Recent interest has focused on the use of high-fibre foods as potential ingredients for lowering the glycaemic index of most carbohydrate-based meals. The objective of this study was to examine glycaemic responses to two defined breakfasts. The reference breakfast and the test breakfast differed only in the type of bread (white vs. wholemeal), and were administered three times to volunteers (2 men, 8 women). Capillary blood glucose was monitored in the fasting state 15, 30, 45, 60, 75, 90, 105 and 120 min after breakfast consumption. The incremental areas under the glucose response curves were calculated for each type of breakfast and compared with those of glucose to determine the glycaemic indices. The glycaemic index of the reference breakfast was 26.6 (±6.2), with that of the test breakfast significantly lower at 18.1 (±6.0). The mixed-food test breakfast with wholemeal bread was rich in soluble fibre (β-glucans) for a lower glycaemic load than the white bread, and provided a lower glycaemic response in the volunteers. The inter-volunteer variability in glycaemic index was large, with some showing lower responses to the test breakfast (glycaemic index, 12.4–21.1) and some showing high responses to the test breakfast (glycaemic index, 25.9–27.4).