Breakfast cereals usually have a high or medium GI score – which will be lowered by adding milk. Lots of things can affect a cereal’s GI, like the heating and processing of the grains during manufacturing to make them safe and tasty to eat. Some intact whole grain cereals, like oats and mueslis, may have a low GI score – but not always: you can’t work out the GI just by looking at a product’s nutrition label. It’s calculated by testing each product in the human body. During manufacturing, cereals can change their GI, so the GI of a cereal made in one market could have a different GI in another market due to differences in production. Batch cooked corn flakes, for example, have a very different GI value (132) from extruded corn flakes (72). It’s not just the GI of a product that’s important. What really matters is the overall impact on blood sugar levels of a whole meal, since foods interact with each other. For instance, the GI of breakfast cereals will significantly decrease when consumed with milk.