Metabolism
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Sugars, starches and the glycaemic index
A group of people consumed two test meals, each containing the same amount of total carbohydrate, on two separate occasions. The graph shows the average changes in blood glucose concentration over 4 hours after each meal.
Can you account for the differences?
What would you expect to see if the subjects had consumed an equivalent amount of glucose?
The carbohydrate in meal 2 is obviously more rapidly and completely digested than that in meal 1.
Glucose does not require digestion, and is rapidly absorbed, so the response of blood glucose to a test dose of glucose would be similar to that after test meal 1 - or perhaps a higher peak achieved slightly more rapidly.
What is meant by the term glycaemic index?
The glycaemic index of a food is the extent to which it raises the blood concentration of glucose (i.e. the area under the curve in the graph shown above), compared with that for a test dose of the equivalent amount of glucose or a standard carbohydrate food that is rapidly digested, such as freshly boiled mashed potato or white bread.