The Glycemic Index(GI)
How is it tested?
In the more than two decades since the development of the Glycemic Index, it has been proven repeatedly that the only way to obtain accurate results is by using blood samples from human subjects and following a precise protocol. Standard protocol requires that ten normal subjects are studied on multiple occasions in the morning after an overnight fast. After a fasting blood sample is obtained, subjects eat the test meal and provide further blood samples at 15, 30, 45, 60, 90 and 120 minutes after starting to eat. Capillary blood is obtained by finger-prick. Each subject conducts one trial of each test food and 3 trials of the reference food. The blood is analyzed in our in-house laboratory and the incremental areas under the blood glucose curves are calculated using the specified method. The ratio of the test food area to the reference food areas gives the GI value.
Health Benefits
You are what you eat!This old adage has been proven correct again when it comes to the GI. The concept of the GI was originally a response to concern for people with impaired insulin responses. Improved stability of blood sugar levels is critical to those people with diabetes, but research has repeatedly shown that stable blood sugar levels have positive health implications for everyone. Diets based on the GI have been shown to:
- Stabilize blood sugar
- Improve body weight
- Decrease visceral fat
- Control appetite
- Improve energy level
- Enhance memory
- Balance mood
- Promote regularity
- Reduce hospital stay after cardiovascular surgery
- Reduce the risk of Age-Related Macular Degeneration
GI Tables
The GI values of some common foods are listed below. Please be aware that values may vary by a small percentage when products are re-tested. Therefore, foods with values within 5 points of each other should be considered identical. In other words, light rye bread, which has a value of 69, will not have a significantly different effect on blood sugar than a bagel which has a value of 74.
This table is only intended to provide a sampling of foods for comparison. For a more extensive listing, please go to www.ajcn.org/cgi/content/full/76/1/5/T1.
