Glycemic Index Testing & Research

Sydney University Glycemic Index Research Service (SUGiRS)

Sydney University GI Research Service (SUGiRS) was established in 1995 to provide a reliable commercial GI testing laboratory for the local and international food industry. Foods are tested in healthy volunteers according to standardised methods that have been validated against laboratories overseas. Insulin, satiety, hunger and other parameters can be assessed simultaneously. SUGiRS has an established reputation for quality, speed and flexibiltiy. We can work with your company to develop new low GI products or help lower the GI of existing ones. Foods that meet nutrition guidelines and have been GI tested can carry the GI symbol. Your results are strictly confidential and are your property. Data are released for publication only with your written approval.

How is the GI measured?

The glycemic index (GI) is a measure of the power of foods (or specifically the carbohydrate in a food) to raise blood sugar (glucose) levels after being eaten. The GI values of foods must be measured using valid scientific methods. It cannot be guessed by looking at the composition of the food. Currently, only a few nutrition research groups around the world provide a legitimate testing service. Professor Jennie Brand-Miller at the Human Nutrition Unit, Sydney University has been at the forefront of glycemic index research for over a decade, and her research group has determined the GI values of more than 2500 foods.

The GI value of a food is determined by feeding 10 or more healthy people a portion of the food containing 50 grams of digestible (available) carbohydrate and then measuring the effect on their blood glucose levels over the next two hours. For each person, the incremental area under their two-hour blood glucose response (glucose iAUC) for this food is then measured. On another occasion, the same 10 people consume an equal-carbohydrate portion of glucose sugar (the reference food) and their two-hour blood glucose response is also measured. A GI value for the test food is then calculated for each person by dividing their glucose iAUC for the test food by their glucose iAUC for the reference food. The final GI value for the test food is the average GI value for the 10 people.

Foods with a high GI score contain rapidly digested carbohydrate, which produces a large rapid rise and fall in the level of blood glucose. In contrast, foods with a low GI score contain slowly digested carbohydrate, which produces a gradual, relatively low rise in the level of blood glucose.

How much does it cost to measure GI values of foods?

Please email us for the current prices.

For 6 products or more
A 10% discount will be given when the GI values of 6 or more products are measured in the one study.

Payment
Two payment options are available: payment of the total fee at the beginning of the study or up-front payment of 30% of the total fee at the beginning of the study and then the remainder on completion of the research. Payment details must be arranged before the research commences and will be confirmed in a formal research agreement. Payments can be made by cheque (addressed to the University of Sydney) or by electronic transfer of funds.

How much food is required to measure GI values?

SUGiRS requires enough of each product to feed 10 people each a portion of the product containing 50 grams of digestible carbohydrate. An additional 15% is also required to cover any potential wastage or repeated test sessions. If you provide us with the nutrient composition of your products, we can tell you exactly how much we would require for GI testing. For liquid foods and beverages, we also need to know how many grams = 100 mL of the product. For many products, the total carbohydrate content listed on the product's label includes both the digestible carbohydrate and the dietary fibre content of the product. If this is the case, the digestible carbohydrate content of the product can be estimated by deducting the dietary fibre content from the total carbohydrate content. If required, SUGIRS can measure the digestible carbohydrate content of any product for an additional $250.

How long does it take to measure GI values of foods?

On average, it takes approximately one week to recruit 10 healthy people to participate in a study and then one week to test each product and up to another week to complete a detailed report of the study. However, as soon as GI values are finalised, they can be emailed or faxed to clients. For larger studies and those involving the measurement of insulin values, an additional one or two weeks may be required to complete all of the biochemical analyses. However, we try to complete each project at the fastest rate possible and usually complete a study earlier than expected. Determining the GI values of foods involves the collection of blood samples from the study participants, so we have to allow time for the participants to recover from the sampling between sessions.

Delivery of products

Products should be sent to the Human Nutrition Unit, School of Molecular Bioscience GO8, corner of Butlin Avenue and Maze Crescent, University of Sydney, NSW, 2006, AUSTRALIA (attention: Fiona Atkinson; contact phone number: +61 (02) 9351 6018. Couriers can deliver the products on week days between 8.30 am - 4.30 pm. If being sent internationally, boxes containing drinks or foods should be labelled with a sign in large letters stating that the box 'contains a small non-commercial consignment of packaged processed foods/drinks for research purposes only.' (If applicable, also state that the products do not contain milk proteins or live organisms). This sign is essential to prevent the foods being held up by the Australian quarantine or customs departments.

Research contract and confidentiality

Before commencing any research project to measure the GI values of foods, SUGiRS requires each company to sign a formal research agreement to confirm the conditions under which the research will be carried out and the ownership and use of the data produced. This agreement confirms that the research will be conducted in a totally confidential manner to protect the company's commercial interests. In addition, the payment details and time-line of the research will be specified.

Contact details

For more information about GI testing at Sydney University, please contact:

Fiona Atkinson: sugirs.manager@sydney.edu.au or
Professor Jennie Brand-Miller: jennie.brandmiller@sydney.edu.au

Sydney University's Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit
School of Molecular Bioscience
Building G08
University of Sydney
NSW 2006
AUSTRALIA

Fiona Atkinson
Ph: (+612) 9351 6018
Fax: (+612) 9351 6022