The glycaemic index, or GI, is an important tool for anyone who wants to control his or her blood sugar levels. The list includes slimmers, diabetics, people with hypoglycaemia, and sportsmen and women. Here's how you can benefit too.

Advertisement

What is the glycaemic index (GI)?
When we eat carbohydrate-rich foods, the carbohydrates are digested in the stomach and intestines and absorbed into the bloodstream in the form of glucose. The glucose in the blood stimulates the pancreas to excrete a hormone called insulin into the blood.

Insulin helps the body cells to take up glucose out of the blood. Body cells use glucose as a source of energy. So eating is followed by an increase in the levels of glucose and insulin in the blood. These increases in blood glucose and insulin levels in the blood can be illustrated by drawing so-called blood glucose and insulin graphs.

About 15 years ago, researchers discovered that carbohydrate foods do not all have the same effect on blood glucose and insulin levels. For example, it was found that if a healthy person eats 50 grams of carbohydrate in the form of white bread, the increase in blood glucose and insulin levels is greater than when the person eats 50 grams of carbohydrate in the form of spaghetti. To explain this difference, scientists coined the term "glycaemic index" or GI.

Definition of the glycaemic index
The GI of a food is defined as the size of the area under the blood glucose graph after eating a portion of the food in question which will supply 50 g of carbohydrate, divided by the size of the area under the blood glucose graph caused by eating 50 g of glucose.

This rather difficult concept becomes easier to understand if we try and imagine two graphs. After eating 50 g of glucose, the graph, which illustrates the increase in the blood glucose level is about 50 percent larger than the graph that shows the increase caused by eating 50 g of carbohydrate from spaghetti. In other words, we can say that the GI of glucose is 100 and the GI of spaghetti is 50.

In recent years, researchers have classified many foods according to their GI. Carbohydrate-rich foods can now be classified into three broad categories, namely high-GI, moderate-GI and low-GI foods.

Why is the glycaemic index important?
The GI is very useful in compiling diets for individuals who experience problems with glucose and insulin metabolism, such as diabetics, people who are overweight, who suffer from high blood pressure, or hypoglycaemia and/or high blood fat levels.

By eating foods with a low GI, which will release glucose slowly and steadily into the blood and do not overly stimulate insulin secretion, diabetes, insulin resistance, obesity and heart disease can either be prevented or controlled.

Use of the GI for sportsmen and women
On the other hand, GI values are being used to design diets for sportsmen and women who require steady blood glucose levels to sustain physical activity for long periods. Sports nutritionists increasingly rely on the use of the GI to develop diets that will prevent fatigue and increase endurance of athletes. - (Dr I.V. van Heerden, DietDoc)

Any questions? Ask DietDoc

Read more on Health24:
Glycaemic index update
GI values of common foods
The GI and sports nutrition

 

Print this article

Rate this article Poor 1 2 3 4 5 Excellent

JOBS

Civil Engineering Technician Gauteng - Johannesburg Staff Nurse Western Cape ICU Registered Nurse Western Cape Maternity Ward Nurse Western Cape Senior Financial Manager CA (SA) R600,000-650,000 Per Annum Cost To Company Gauteng - Johannesburg Senior Financial Manager CA (SA) R600,000-650,000 Per Annum Cost To Company Gauteng - Johannesburg Business Development Manager R400,000-550,000 Per Annum Cost To Company Gauteng - East Rand Cost / Clinical Audit Clerk (Medical Aid) Western Cape Find more jobs Register your CV Post a job