Glycaemic Index (GI)

Glycaemic Index (GI)

• What is the glycaemic index (GI)?
• How are carbohydrates divided into groups?
• How is the glycaemic index determined?
• Factors affecting the glycaemic index

 

• Glycaemic index and metabolism
• Glycaemic index and meals
• Glycaemic index and medical conditions
• How to incorporate low glycaemic foods into your lifestyle

 

glycaemic index (GI) is obtained by measuring the effect that a carbohydrate containing food has on blood sugar levels, compared to the effect of the same amount of pure sugar, on blood sugar levels. The Dietary Guidelines for Australians recommend that carbohydrates should make up at least 55% of total daily calories.

In more recent times, the quality of these carbohydrates has been shown to also be important in blood sugar control. Even though different foods may contain the same amounts of carbohydrates, the effects on blood sugar control may be totally different. This has lead to the development of measures such as the GI of a food product. Research has shown that by consuming a diet with a lower GI and rich in healthy foods, people with diabetes can reduce their average blood sugar levels and reduce the risk of complications. Other studies have also shown that diets that have an increased amount of high GI foods are associated with an increased risk of developing heart disease, type 2 diabetes and disease of the arteries.  

eye, kidney and nerve damage.

Table 1: List of foods in relation to their GI

 

hormone called insulin to break it down. Insulin acts to lower the body’s sugar levels. When the blood sugar levels decrease to a particular level, the brain is sent a signal and you become hungry again.

If high GI foods are continually consumed, the rapid breakdown results in sharp decreases in your blood sugar levels, and you feel full for shorter periods of time. You can see that this sets up a continual cycle, causing weight gain and the development of diseases such as high cholesterol and blood pressure.

If you have diabetes, your insulin levels are either low or you are resistant to the effects of insulin. This allows blood sugar levels to increase – with high GI foods, the rapid surge in blood sugar levels is more difficult to control with medications or injectable insulin. After a period of time, prolonged high blood sugar levels leads to damage to many organs of the body, such as the blood vessels and nerves.

If you eat foods that are low in GI, blood sugar levels can be sustained at a lower level over a longer period of time. There is less demand on your pancreas if it is still producing insulin and you feel satisfied for longer. If your body does not produce any more insulin, medications and injectable insulin can control the levels more steadily. The sugars in the blood can be directed towards the cells to be used as energy rather than being stored as fat.

metabolic syndrome, a combination of risk factors such as increased weight (obesity), high blood pressure, high cholesterol and fat levels, and resistance to insulin. A diet with many high GI foods often leads to worsening of these risk factors, contributing to events such as fat build up on the inside of arteries (atherosclerosis) and high blood pressure levels.

Nutrition. 

Reference

1. Augustin L, Franceschi S, Jenkins D, et al. Glycemic index in chronic disease: a review, European Journal of Clinical Nutrition, 2002; 56: 1049-107140)
2. Bate K, Jerums G. Preventing complications of diabetes, MJA 2003; 179 (9): 498-503
3. Behall KM, Scholfield DJ, Canary J. Effect of starch structure on glucose and insulin responses in adults. Am. J. Clin. Nutr. 1998, 47: 428-432.
4. Ludwig, DS. The glycemic index: physiological mechanisms relating to obesity, diabetes, and cardiovascular disease. JAMA 2002; 287:2414.
5. Virkamaki A, Ueki K, Kahn C. Protein-ï€protein interaction in insulin signalling and the molecular mechanisms of insulin resistance. Review. J. Clin. Invest.,1999; 103: 931-943.
6. Willett W, Manson J, Liu S. Glycemic index, glycemic load, and risk of type 2 diabetes. Am J Clin Nutr 2002; 76:274S.
7. Wolever, TM, Katzman-Relle, L, Jenkins, AL, et al. Glycemic index of 102 complex carbohydrate foods in patients with diabetes. Nutr Res 1994; 14:651.
8. Wolever, TM, Vorster, HH, Bjorck, I, et al. Determination of the glycemic index of foods: interlaboratory study. Eur J Clin Nutr 2003; 57:475.

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Article Dates:

Modified: 30/12/2010

Created: 14/6/2007

Glycaemic Index (GI)