1 June 2013

GI Update with Prof Jennie Brand-Miller

Prof Jennie Brand-Miller answers your questions. 


‘How about giving us the GL of your recipes? Calories, fat, etc are all very interesting, but you’re supposed to be the “Glycemic Index Newsletter” and I find it frustrating that I have to go searching and calculating the GL of your recipes.’
Most of us have great faith in numbers, especially ones that are boldly printed in black and white on labels and in books. And with the current trend to count each and every gram of carbohydrate (or every calorie/kilojoule) in a food or beverage, it is easy to understand why you like many other people feel that you should be adding up the GI values of your meals. Relax. You absolutely don’t need calculators, pen and paper to eat the low GI way.

GL or glycemic load: First of all, there's no need to calculate the GL unless you’re a researcher doing studies based on high and low GI diets. If you can verify that the main carbohydrate source in your recipe is low GI (e.g. it’s a legume), then the GL will automatically be relatively low. To calculate the glycemic load (GL), you need to know both the available carbohydrate content (easy) as well as the GI (not always easy). Then you use the equation: GL = grams of carbohydrate per serving x GI divided by 100. If there's only one carbohydrate source e.g. spaghetti, then it's a simple task. But if you've got a mix of carbohydrate sources or you start with a flour, then it gets a bit tricky.

GI or glycemic index: Unlike grams of carbohydrate and other nutrient or calorie (kilojoule) counts, the GI is a measure of quality – not quantity. A useful analogy is that of mixing paints – the final colour will reflect the dominant colour used, not simply the sum of its parts. It’s true that researchers sometimes calculate what is called the average dietary GI, or to be more precise, the weighted average GI – where the weighting is a percentage value representing the proportion of total carbohydrate contributed by each individual food and beverage. But this is for studies to be published in peer-reviewed scientific journals. For everyday use, this is simply not necessary as we know from what’s called ‘dietary modelling’ that simply replacing most of the high GI carbs you eat with medium or low GI ones will lower the GI of the average person’s diet sufficiently to reduce their risk of developing type 2 diabetes and will also help them achieve and maintain a healthier weight. In addition, numerous studies have shown that people with diabetes can improve their glycated hemoglobin (a measure of their average blood glucose level over a 3–4 month period) simply by lowering the GI of their diet. In these studies, the people did not have to calculate their daily GI values – it was not necessary: they just used the substitution model (look how easy it is):

Swap it

Don't sweat the small stuff:
Just like grams of carbohydrate and other nutrients and calories/kilojoules, GI values aren’t 100% accurate – for all of the same reasons: foods are grown in different soils, under different weather conditions, and consequently, all have a slightly different nutrient composition. We suggest you simply swap the high GI carbs you eat at most meals for low or moderate GI counterparts because this will help you will achieve a low (or lower) GI diet overall. And don’t forget about the total calories/kilojoules, type of fat and sodium content of your meals – GI is only one part of healthy eating.

Latest GI values - belVita biscuits 
A year ago we reported on the GI values of three flavours of belVita, a European-style breakfast biscuit intended to be consumed as part of a balanced breakfast with a portion of fruit and a serving of low-fat dairy. Kraft Foods Australia has now added two more flavours to the range:
• belVita Breakfast Cranberry – GI40, 34g carbs, 835kJ
• belVita Breakfast Honey & Nut with choc chips – GI46, 34g carbs, 975kJ  

GI testing by an accredited laboratory
North America

Dr Alexandra Jenkins
Glycemic Index Laboratories
20 Victoria Street, Suite 300
Toronto, Ontario M5C 298 Canada
Phone +1 416 861 0506
Email info@gilabs.com
Web www.gilabs.com

Fiona Atkinson
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit, School of Molecular and Microbial Biosciences
Sydney University
NSW 2006 Australia
Phone + 61 2 9351 6018
Fax: + 61 2 9351 6022
Email sugirs@mmb.usyd.edu.au
Web www.glycemicindex.com