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 Bothâ¢, 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 (Lifescanâ¢). 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 Wheatâ¢, 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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08122008-102538 |
| Date | 12 August 2008 |
| Creators | van Zyl, Martha Jacomina |
| Contributors | Dr CM Walsh, Prof M Slabber-Stretch |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08122008-102538/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0025 seconds