Biology Reference
In-Depth Information
the chemical classification of carbohydrates into mono-, di-, oligo-, and
polysaccharides as well as the physiological classification into glycemic
and nonglycemic carbohydrates are relevant in their role in elevating or
modulating blood glucose. Hence, determining the glycemic index (GI)
of foods is a very useful technique for assessing the quality of carbohydrate
foods. This simple and straightforward measure of carbohydrate quality
needs to be promoted and adapted by clinicians while providing nutritional
advice to diabetic patients not only for managing normal glycemic control
but also to control the associated complications related to lipid profile, blood
pressure, and weight management (
Kirpitch & Maryniuk, 2011
)
.
GI may be defined as a measure of the ability of a food product to raise
blood glucose. The glycemic effects of carbohydrates are measured by their
ability to raise blood glucose levels above the baseline for 2-3 h after con-
sumption. This measure of postprandial increase in blood glucose allows the
derivation of a numerical value called GI that can be used for categorizing
carbohydrate foods as beneficial or harmful for our health. GI is expressed as
a percentage of the value obtained by calculating the ratio of the incremental
area under the glucose curve for a food containing typically 50 g available
carbohydrate to the incremental area under the glucose curve of 50 g of a
reference food that is pure glucose (
Jenkins et al., 1981
)
. Although the qual-
ity of carbohydrate is indicated by GI, the quantity of carbohydrate con-
sumed is equally important and this led to the coining of another term
called glycemic load (GL), which is the product of GI of a food and the
amount of carbohydrates in a serving of that food.
Burkitt and Trowell (1977)
first proposed that the risk associated with
metabolic diseases such as diabetes and coronary heart diseases may be
reduced by increasing the consumption of slowly absorbed carbohydrates
such as those in dietary fiber. Their “fiber hypothesis” was then extended
into the concept of GI by Jenkins and coworkers (
Jenkins, Kendall,
et al., 2002
), who first published the index classifying 62 commonly con-
sumed foods based on their effect on postprandial blood glucose in human
subjects (
Jenkins et al., 1981
). Ever since, a number of foods have been
tested all over the world to generate the International Table of GI and
GL values for 2487 individual food items, citing 205 separate studies
(
Atkinson, Foster-Powell, & Brand-Miller, 2008
)
. This has served as the
most comprehensive list of all food items allowing us to ensure normal gly-
cemic control based on the published values of GI and GL in both healthy
and diabetic subjects. GI is the measure of the change in blood glucose con-
centration following the consumption of a food based on a constant level of
