All carbohydrates will break down into glucose in the bloodstream and raise blood glucose. How much they raise blood glucose will depend on how quickly they break down to glucose. This concept of how fast food breaks down into glucose is called glycaemic index (GI).
The food that breaks down the fastest into glucose in the bloodstream is glucose itself. Since it’s super quick, it’s given a score of 100. Every other food is then compared to glucose and given a score out of 100 which is determined by measuring the effect of the food on the resultant blood glucose in the bloodstream.
The lower the score (less than 55), the slower the food will break down into blood glucose. A slower release is optimal because it will give insulin time to respond to the blood glucose in the bloodstream and ensure it doesn’t sit too long in the bloodstream.
A rapid breakdown of food into glucose (high-GI) will mean a fast increase of blood glucose and the insulin may not be able to respond optimally to the glucose spike, meaning that the glucose will sit too long in the bloodstream and start causing damage in the blood vessels. If this happens too often it can cause diabetes complications in the large blood vessels (heart) and smaller vessels (kidney, eyes and feet).
Glycaemic Index FOODS
LOW-GI (<55) MEDIUM-GI (56-69) HIGH-GI (70>)
| Grains/StarchDairyDairy
Rice bran |
27 |
Vegetables
Asparagus |
15 |
Dairy
Low-fat yoghurt |
14 |
Legumes
Peanuts |
21 |
| Bran cereal | 42 | Broccoli | 15 | Plain yoghurt | 14 | Beans, dried | 40 |
| Spaghetti | 42 | Celery | 15 | Whole milk | 27 | Lentils | 41 |
| Sweet corn | 54 | Cucumber | 15 | Soya milk | 30 | Kidney beans | 41 |
| White rice | 64 | Lettuce | 15 | Fat-free milk | 32 | Split peas | 45 |
| Couscous | 65 | Peppers | 15 | Skim milk | 32 | Lima beans | 46 |
| Wholewheat bread | 71 | Spinach | 15 | Chocolate milk | 35 | Chickpeas | 47 |
| Muesli | 80 | Tomatoes | 15 | Fruit yoghurt | 36 | Pinto beans | 55 |
| Baked
potato |
85 | Cooked
carrots |
39 | Ice cream | 61 | Black-eyed beans | 59 |
| Oatmeal | 87 | ||||||
| Taco shells | 97 | ||||||
| White bread | 100 | ||||||
| Bagel, white | 103 |
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