Points of Interest

Many people intuitively appreciate the concept of GI as it relates to various foods. What I would like to draw to your attention are some interesting specifics that could lower the GI of a meal by 50% or more.

Breads

When it comes to GI not all breads are created equal. The breads that have highly processed refined flour (white or whole wheat) are going to have a much higher GI (70) than breads made with stoneground flour (coarse) containing whole grains (GI=53). These coarse, heavy, chewy breads are digested more slowly. The problem with highly processed flours is that the high speed milling process pulverizes the starch into tiny particles increasing the surface area and accelerating the rate of digestion resulting in a higher GI, as high in fact as a Mars Almond Bar! (GI=68)

Rice

Nor is all rice created equal. Our discussion above regarding amylose and amylopectin applies especially to rice. White rice has a high GI (72) and the main starch is amylopectin. By contrast, basmati rice is mostly amylose and has a much lower GI (58). You should also try the long grain brown rice with the germ and husk as this has a favorable GI (55) and better nutritional value.

Pasta

Although pasta in general already has a moderate (GI~55-65) it can be reduced by preparing it al dente (still very firm) which slows down its rate of digestion.

Sugars

The GI values determined for various sugars are interesting. Table sugar, raw cane sugar and honey are all essentially sucrose (a glucose and fructose molecule linked together) and while they may vary slightly in their micronutrients they all have similar GI values (65). They are not as high as white bread either because the body is very slow to process fructose (GI=23). That also explains why many fruits have low GI values as many contain mostly fructose as a simple sugar, making them an excellent snack.

Legumes

Legumes such as lentils, kidney beans, chick peas and navy beans all have GIs in the 27-38 range. Need I say more? When included in a meal they can help reduce the GI of the whole meal. In addition they are low in fat and contain high amounts of fibre that can improve your cholesterol profile.

Summary

If you are a diabetic this information may provide an additional tool to help manage blood sugars more effectively. We are all different so test your blood sugars regularly and learn which foods and combinations work for you. This doesn't mean that you should sit down before each meal with a calculator trying to determine the GI of your meal to the nearest decimal point. The GI is simply a guide to help you understand and more accurately estimate the impact of a meal on your blood sugars. You can then make appropriate food selections.

Eric Norman is a research scientist investigating heart disease in post-menopausal women and in individuals with type II diabetes.

References

1. Wolever, T. et al.. The Glucose Revoluation: The Authoritative Guide to the Glycemic Index. Marlowe and Company. 1999.
2. Weil, A. Eating Well For Optimal Health. Alfred A. Knopf. New York. 2000.
3. (You can find an extensive list of GI values for a variety of foods in The Glucose Revolution listed in the references.)