Size: Grains that are in their original form like whole
wheat and barley have a lower GI than other forms of
these substances such as refined flours.
Processing: The GI of a food will be significantly raised by the amount of pounding, mixing, or grinding it endures. The increase
occurs because the particle size is decreased, so the body does not need to do as much work to break the food down during
Fiber content: Soluble fiber slows down the emptying of bowels, so foods containing this type of fiber will have a lower index.
Insoluble fiber has little effect, if any, on the digestion and absorption of carbohydrates.
Type of starch: Starch can have two different compositions,
amylose and amylopectin. Amylose has long straight chains of glucose molecules while amylopectin has branched chains.
Long grain rice is an example of a starch that has high amylose, while short grain rice has more amylopectin. Amylose is packed
more densely together because it is unbranched and is therefore harder for the body to digest, giving it a lower glycemic
Sugar: Sugar has surprisingly been shown to lower the glycemic index of foods that have a very high glycemic index. For example,
in baked goods, sugar tends to bind to the fluid while baking, which prevents the flour from binding to it. This prevents
gelatinization, which is where starch is cooked in liquid, causing the starch granules to swell. This often bursts the individual
starch molecules making them quite easy to digest.
Protein: Additional protein generally lowers the GI of most
foods. However, protein levels should remain in the AMDR for best health.
Acid: Many experiemental tests have indicated that the more acidic the food, the lower the glycemic index.