Determination of the glycaemic index of three types of Albany Superior bread

English: The glycaemic index (GI) concept was introduced as a means of classifying different sources of carbohydrates (CHO) and CHO-rich foods in the diet, according to their effect on postprandial glycaemia since different carbohydrate containing foods have different effects on blood glucose responses. The GI is defined as the incremental area under the blood glucose response curve of a 50 g glycaemic (available) carbohydrate portion of a test food expressed as a percentage of the response to the same amount of glycaemic CHO from a standard food taken by the same subject. Though not the only factor that will determine whether the food should be included in the diet or not, the GI can be used alongside current dietary guidelines like the Food Based Dietary Guidelines and exchange lists to guide consumers in choosing a particular food with a predicted known effect on blood glucose levels and homeostasis. Variation in the GI values for apparently similar foods may reflect both methodologic factors as well as true differences in the physical and chemical characteristics of the specific food. Differences in GI values of similar foods could also be due to inherent botanical differences from country to country. Two similar foods may also have different ingredients, different processing methods or different degree of gelatinisation resulting in significant variation in the rate of CHO digestion and consequently the GI value. Methodological variables which include food-portion size, the method of blood sampling, sample size and subject characteristics, standard food, available CHO, volume and type of drinks consumed with test meals can markedly affect the interpretation of the glycaemic responses and the GI value obtained. Tiger Brands commissioned an independent assessment of the GIs of three Albany Superior™ breads namely Best of Both™, Brown™ and Whole Wheat™ bread carried out under strictly standardised conditions using methods complying with the most recent internationally accepted methodology. Methods Twenty healthy, fasting male volunteers, aged 18-27 years, each randomly consumed six different test meals consisting of 50 g available carbohydrates from three different test foods (three types of Albany Superior breads) and one type of standard food (glucose) (repeated three times in each subject) according to a Latin square design. Finger-prick capillary blood was collected fasting and within 10-15 min after the first bite was taken for every 15 min time interval for the first hour and thereafter for every 30 min time interval for the second hour, using One Touch Ultra™ test strips and One Touch Ultra™ glucometers (Lifescan™). The AUC and GI for the three different breads, were calculated using the mean of the three glucose responses (standard meals) as standard. Statistically significant differences were also determined. Results The mean GIs were 78.44, 72.01 and 79.62 for Whole Wheat™, Brown™ and Best of Both™ bread respectively. No statistically significant differences were found between the GIs of the three different Albany Superior™ breads. Conclusions From the study it can be concluded that the three different Albany Superior™ breads fell between the intermediate and high categories. Recommendations It is recommended that the methodological guidelines determined by the GI Task Force should be followed. It is also important to inform patients and consumers that in using the GI to choose CHO foods it is a fact that physiological responses to a food may vary between individuals and that it is normal for a specific food to have a high GI in some individuals and a medium or even a low GI in others. For labeling purposes it is recommended that the GI is presented as a mean with 95% confidence intervals.