5.1 The role of the glycaemic index
The glycaemic index (GI) describes the rate at which carbohydrate foods are digested (broken down into glucose) and enter the bloodstream as glucose. You may already be aware of GI in the context of weight loss diets and healthy eating. The GI also has an important role in maintaining energy levels for physical activity and sports performance. The GI is a ranking of foods from zero to 100, based on the rate at which a carbohydrate food is broken down into glucose and enters the bloodstream, resulting in a rise in the blood glucose level. Pure glucose has a GI of 100 and serves as a reference point to which all carbohydrate foods are compared. A food that has a GI of 55 or over is regarded as high GI and food that has a GI of less than 55 is regarded as low GI (The University of Sydney, 2017).
Figure 5 shows the change in blood glucose levels over time in response to the intake of high and low GI foods. Click on High GI and Low GI for an explanation of each one.
Some examples of high, moderate and low GI foods are shown in Table 2.
Table 2 High, moderate and low glycaemic index foods
|High GI||Moderate GI||Low GI|
|Glucose 100||Cornflakes 81||Potato (boiled) 56|
|Parsnips 97||Chips 75||Sweet potato 54|
|French baguette 95||Bagel 72||Bananas 52|
|Lucozade Original 95||Watermelon 72||White pasta 50|
|Honey 87||Wholemeal bread 71||Muesli 49|
|Potato (baked) 85||White bread 70||Porridge oats 49|
|Sports drinks 70||Baked beans 48|
|Weetabix 66||Apples 38|
|White rice 64||Yogurt 36|
|Shredded Wheat 64||Chickpeas 28|
|Raisins 64||Whole milk 27|