Glycaemic Load (GL)

Glycaemic Load (GL)

• What is the glycaemic load (GL)?
• How is the glycaemic load calculated?
• Factors affecting the glycaemic load  

 

• Metabolism and glycaemic load
• Medical conditions and glycaemic load
• Lowering dietary glycaemic load
   

 

glycaemic index (GI) – a value that 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. However, the problem with the GI is that it doesn’t provide an accurate picture of the entire blood sugar raising potential of the food. The blood sugar response depends on both the quantity and quality of carbohydrates consumed. The GI only provides us with an idea of how rapidly a carbohydrate turns into sugar, but not how much of that carbohydrate is in a food serving.

The glycaemic load (GL) is an extension of the GI, taking into account the quantity of carbohydrates as well. The GL is obtained by multiplying the GI value by the carbohydrate content of the food. This provides us with a more accurate picture of the overall effect that the food product has on blood sugar levels. Clinical studies have shown that the dietary GL is linked to risk factors for heart major vessel disease, and obesity, although data is still being collected.   

diabetes, the GL has been shown to be a more accurate and reflective predictor on blood sugar levels. By adhering to a diet with a low GL, diabetics can reduce their average blood sugar levels and lower their risks of developing complications such as eye, kidney and nerve damage.

blood sugar levels than a serving of potatoes.

In summary, the GI of potatoes is not a misleading value because potatoes are carbohydrate dense, thus their GL is also high. Watermelon on the other hand contains only a small percentage of carbohydrates, so although they have a high GI level, their GL is low.

Medical conditions and glycaemic load

Looking at over 75,000 healthy middle aged women involved in the Nurse’s Health Study, the impact of carbohydrate consumption on long term heart and major vessel health was assessed. They found that diets with a high GL value correlated with increased risk of heart and major vessel disease, regardless of whether the women had conventional risk factors for heart disease or not (ie high blood pressure, high cholesterol levels, family history, smoking, etc). There was also a strong association with weight – particularly in overweight women, a strong positive association was seen between dietary GL and cardiovascular disease. In lean women, there was little association between the two. Another study was performed in 280 postmenopausal women, which showed that dietary GL was inversely related to the level of good cholesterol (HDL) and directly related to bad cholesterols such as LDL and triglycerides.

If you have diabetes, blood sugar levels and insulin resistance is important in understanding and management of your disease. A chronically high blood sugar level after meals has been linked to increased insulin resistance and decreased production of insulin. Some studies performed in patients show that there is a lower rise in blood sugar levels if a meal with a low glycaemic index or glycaemic load is consumed. In the Framingham Study, diets high in total fibre and whole grain were associated with decreased insulin resistance. Elevated dietary glycaemic index and glycaemic load were associated with insulin resistance. A higher glycaemic intake and lower intake of fibre were also shown to be linked to an increased risk of the metabolic syndrome.

Nutrition. 

Reference

1. 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.
2. Foster K, Holt S, Brand-Miller J. International table of glycaemic index and glycaemic load values: 2002. Am J Clin Nutr. 2002; 76:5-56.
3. Liu S, Manson J. Dietary carbohydrates, physical inactivity, obesity, and the ‘metabolic syndrome’ as predictors of coronary heart disease. Curr Opin Lipidol 2001; 12:395.
4. Liu S, Willett W, Stampfer M, et al. A prospective study of dietary glycaemic load, carbohydrate intake, and risk of coronary heart disease in US women. Am J Clin Nutr 2000; 71:1455-61.
5. McKeown N, Meigs J, Liu S, et al. Carbohydrate nutrition, insulin resistance, and the prevalence of the metabolic syndrome in the Framingham Offspring Cohort. Diabetes Care 2004; 27:538.
6. Willett W, Manson J, Liu, S. Glycaemic index, glycaemic load, and risk of type 2 diabetes. Am J Clin Nutr 2002; 76:274S.
7. Willet W, GL Reflects Actual Carbohydrate Burden, 2006, [cited 20 June 2007] Available from URL: http://www.drfood.citymax.com/articles/article/3407261/49370.htm

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Article Dates:

Modified: 30/12/2010

Created: 2/7/2007

Glycaemic Load (GL)