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Sydney University’s Glycemic Index Research Service. Report #1918

A study to measure the Glycemic Index values of NZFOS+ Yacon Concentrate syrup product

Using glucose as the reference food (GI = 100), foods with a GI value less than 55 are currently considered to be low-GI foods. Foods with a GI value between 56-69 are medium- or moderate-GI foods, and foods with a GI value of 70 or more are high-GI foods. The NZFOS+ Yacon Concentrate produced GI value of 40, which places the product within the low GI category. The GI value observed for the product is only valid as long as the formulations (ingredients and processing methods) remain the same. Any changes made to the product can impact its GI value, and therefore any modified formulations may need to have its GI value remeasured.

GI values are measured using portions of foods and drinks that contain either 25 or 50 grams of digestible carbohydrate, but these may not be similar to the amounts of these products typically consumed by people in normal environments. It is possible to calculate a glycemic load (GL) value for any sized portion of a carbohydrate-containing food, as long as you know its GI value. The GL value for a food or drink is calculated by multiplying the amount of available carbohydrate in the portion of the food or drink by its GI value and then dividing by 100.

Similar to GI values, GL values are useful for helping people identify which types and amounts of foods will produce relatively lower blood glucose responses after consumption. Currently, the consensus is that GL values of 10 or less are low GL; GL values of 11-19 are medium GL values; and GL values of 20 or more are high GL values. The glycemic load value for a standard serve of the syrup tested in this study is listed below:

  • NZFOS+ Yacon Concentrate (12 g serve): (4.1 x 40)/100 = 2

The GI values of foods must be tested scientifically. At this stage, only a few research groups around the world currently provide a legitimate testing service. The University of Sydney has been at the forefront of glycemic index research for over a decade and has determined GI values for more than 3500 foods. In 1999, the Human Nutrition Unit established a commercial GI testing unit called ‘Sydney University’s Glycemic Index Research Service’ (SUGiRS) to meet the increasing demand for GI research by local and international food manufacturers and pharmaceutical companies.

Fiona Atkinson and Jennie Brand-Miller are co-authors of The International Tables of Glycemic Index published by the scientific journal, Diabetes Care, in 2008. Previous editions of the International Tables (published in 1995 and  2002) have proven to be an important reference for health professionals when planning therapeutic diets for people with diabetes. Jennie Brand-Miller’s books, The GI Factor and related pocketbooks on diabetes, heart disease and weight reduction, are aimed at laypeople and health professionals, and have sold more than 150,000 copies in Australia since 1996. A British edition of The GI Factor was released in 1997 and a North American edition (The Glucose Revolution) was released in July 1999. Each edition of the book includes tables listing the GI values of more than 350 different foods, many of which were tested at the University of Sydney. The glycemic index has been discussed in a number of best-selling books and in magazine articles in relation to a range of health topics such as diabetes, breast cancer and weight control. Publications such as these and ongoing research promoting the healthy nature of low-GI foods have generated an increasing demand for GI research.

Fiona Atkinson and Jennie Brand-Miller (June, 2019) The University of Sydney. Sydney University’s Glycemic Index Research Service. Report #1918.

Link: Sydney University’s Glycemic Index Research Service. Report #1918

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