Articles
Glycaemic Load
What is the glycaemic load?
Many of us will now be familiar with the term “Glycaemic index (GI)”. The GI describes the type of carbohydrates in food. It is a measure of that foods ability to raise blood glucose levels. Foods with a high GI contain carbohydrates that can have a dramatic effect on blood glucose levels.
The GI does not take into account how much carbohydrate a normal serve of food contains. A food may contain carbohydrates that will raise blood glucose levels (high GI), but a normal serve of that food may only contain small quantities of carbohydrates.
An example of this is pumpkin. Pumpkin has a GI of 75. This may discourage us from eating pumpkin if we have diabetes. A normal serving size of pumpkin is 80g. The available carbohydrate per serve is only 4g. This gives a glycaemic load of 3 (very low).
Glycaemic Load (GL) is a measure of the amount and type of carbohydrate in a food that allows us to predict blood glucose responses to a meal. The lower the GL the lower the effect on blood glucose levels.
How is it calculated?
Glycaemic load = (GI x carbohydrate per serving)/100
Example:
An apple:
GI = 40, Carbohydrate per apple = 15 grams
GL = 6
A potato:
GI = 90, Carbohydrate per potato = 20 grams
GL = 18
From this result we can say the effect of the potato including insulin demand may be three times higher than the apple.
Is it then better to use the GL instead of the GI?
Even though the GI only takes into account the quality and not the quantity of carbohydrate in a meal, research has shown that both are good predictors of overall disease risk.
The GL does suggest that the higher the consumption of high carbohydrate, high GI foods, the more adverse the outcome. The problem is that there is a worry it may lead to a rise in low carbohydrate diets. These diets tend to be high in saturated fat, protein and energy.
So the best recommendation
Use the GI to help you compare between products of similar carbohydrate content such as rice varieties. When the amount of carbohydrate differs use the GL as a predictor of blood glucose rise.
Reference: J Brand-Miller, K Foster-Powell, S Colagiuri. 2002. The new glucose revolution. Hodder: Australia
Added to site on : Friday, 4 July 2003