STEPHEN J. CHEETHAM¹, VICKI J. HARBER¹,
LINDA J. MCCARGAR², SCOTT C. FORBES³, GORDON J. BELL¹*
*Corresponding Author
1. Faculty of Physical Education and Recreation,
University of Alberta, Edmonton, Alberta, T6G 2H9, Canada
2. Faculty of Agricultural, Food and Nutritional Science,
University of Alberta, Edmonton, Alberta, T6G2H9, Canada
3. Human Kinetics, Okanagan College, Penticton Campus, British Columbia, V2A 8E1, Canada

Picture on the left: S. J. Cheetham

Abstract

The purpose of this study was to examine the metabolic and hormonal responses to commercially available nutrition bars that differed in glycemic index and load.  Three randomized conditions were matched for either carbohydrate content and/or caloric intake but differed in glycemic index and load. The results showed that a similar blood glucose concentration was achieved in each experimental trial despite differences in glycemic index or load. However, the nutrition bar with the lowest glycemic index and load resulted in the lowest insulin and highest glucagon concentration in serum during the postprandial period. Non-esterified fatty acids were lowest in the fasted state and with the moderate glycemic index and high load condition. Thus, for the same or lower amount of carbohydrate intake, the nutrition bar with the lowest glycemic index and load produced similar post prandial blood glucose responses to those of a higher glycemic index and load but this occurred as a result of significantly different gluco-regulatory and counter-regulatory hormone responses.

INTRODUCTION

The glycemic index (GI) was introduced as a standardized system of classification that indicates how foods containing carbohydrate (CHO) influence blood glucose levels in comparison to a reference standard containing 50 grams of glucose or white bread (1-3). The GI has been shown to be dependent on the rate at which various foods are digested and absorbed as well as the type of carbohydrate ingested (2, 4). It has been criticized for inadequately characterizing the glycemic response to portion sizes typically found in whole diets (5). Since the glycemic effect of a meal or diet is a product of both the type and quantity of the CHO, the glycemic load (GL) was introduced in an attempt to more accurately quantify the overall glycemic response to meals (6, 7). Proponents of both the GI and GL advocate their efficacy in the preven ... ...