As mentioned in the glycaemic index article, the GI of foods vary. While most refined foods have a high GI, which is what you want to avoid, not every unrefined food will have a low GI. A typical example is bread – if you are keeping to a low GI diet, then white, brown and wholewheat bread are a problem as they are medium to high GI foods.
Here are some of the low and high GI foods. For diabetics, it is best to test your individual tolerance to these foods. Some may cause spikes in your blood sugar levels even though they are low GI foods. Another factor that may alter the glycaemic index is the temperature of the food as well as cooking methods and storage.
Low GI Foods
Some of these foods may become high GI foods when processed.
- Dried beans.
- Canned baked beans.
- Cooked peas and lentils.
- Most fruits are low GI in small quantities except for tropical fruits. Avoid large amounts of fruit juices.
- Dried fruits including dates and raisins should be eaten in small quantities.
- All vegetables except those listed as high GI foods.
- Breakfast cereals – all high fibre, bran and muesli are low GI. Oat bran and rolled oats are low GI but instant oats is high GI.
- Durum wheat pasta.
- Rice – all types, white, brown or basmati.
- Mealies (corn). For more information on mealie meal, refer to the bottom.
- Rye bread and crackers.
- Low GI or diabetic jams.
- Raw honey.
High GI Foods
The glycaemic index of some of these foods may be altered when eaten with protein and other high fibre foods.
- Sugar (white or brown), glucose, molasses and honey.
- Melons and other tropical fruit.
- Potatoes, pumpkin, parsnips, carrots and gem squash.
- Cereals – instant oats, popped rice, corn flakes and sorghum.
- Instant noodles.
- Fried chips.
- White, brown and wholewheat bread.
- Cakes and biscuits, except those made of rye.
- Most carbonated drinks containing sugar, sports and energy drinks.
Factors that Alter Glycaemic Index
The individual glycaemic index cannot be altered significantly but when combined with other foods in the meal, the absorption may be affected. The following can affect the absorption rate of high GI foods.
- Soluble fibre.
- Temperature – certain foods, particularly starchy foods, are absorbed faster when eaten warm or hot. Cooked mealie meal (pap/phutu) is a typical example.
- Storage – freezing food after cooking and then reheating it will also affect glycaemic index especially for foods that are high in starch.