CAN WE CUT OUR AVERAGE DIETARY GI AND GL?
In July GI News, I made the point that: “We now know that glycemic load is the most powerful predictor of blood glucose and insulin levels. You can lower GL by substituting low GI foods for high GI foods, or by consuming less carbohydrate, or by a bit of both.” There is also a rapidly growing body of evidence that low GI or GL diets assist with weight loss, weight maintenance and chronic disease prevention and management. In this issue, I look at a good news health literacy education story: how Australians successfully lowered the average dietary GI of their diets between 1995 and 2011/12 and as a flow-on effect, the GL.
First, a bit of background. David Jenkins and colleagues introduced the glycemic index (GI) in 1981 by comparing the postprandial blood glucose incremental area under curve of different carbohydrate foods. Numerous studies were then conducted to test the GI of different foods and the first International GI Table was published in 1995 followed a year later by the popular book, The GI Factor, giving consumers clear, accessible and authoritative information on the glycemic index, why it mattered and how to go low GI (“learn to love lentils” was a catchphrase). The free database of GI values on the University of Sydney GI website (www.glycemicindex.com) went live late 2000 (or early 2001) thanks to Assoc Prof Gareth Denyer; and in July 2005, GI News arrived on the scene as an online newsletter (http://ginews.blogspot.com.au) thanks to Dr Scott Dickinson.
But it was clearly time to involve food manufacturers. In Australia, the Glycemic Index Foundation, a not-for-profit health promotion charity, developed the GI Symbol Program (a front-of-pack food endorsement program) in 2002 to help consumers make healthy low GI choices when grocery shopping easier. Foods that carry the Symbol have been GI tested at an accredited laboratory and meet strict category-specific nutrient criteria consistent with international dietary guidelines for kilojoules, saturated fat and sodium, and where appropriate, fibre and calcium. Since then a range of “good carbs” have carried the Symbol including breads, breakfast cereals, pasta, rice, noodles, apples, pears, potatoes, milk (the real stuff) and yoghurt.
But did Australian consumers actually make use of all this information about the GI of foods? A study in the American Journal of Clinical Nutrition suggests that they did (Australian are good adopters and early adopters). Using data from Australia’s most recent national nutrition surveys, the researchers set out to see if dietary GI and GL had changed between the years 1995 and 2011/2. They found that dietary GI decreased from 56.5% to 53.9%. They put this down primarily to a reduction in the intake of added sugars (primarily sucrose in Australia), honey and syrups, sweetened beverages, juices and potatoes. But low GI breads and breakfast cereals (many with the GI Symbol) have been very successful product ranges in Australia. These results are encouraging. There is no reason why this cannot be achieved elsewhere in the world.
What next? Here at GI News, we would like to see the GI (and GL of a serving) included on Nutrition Information Panels/Nutrition Facts Labels to help consumers manage their weight and reduce their risk of chronic disease; and to help those with diabetes manage their blood glucose levels. It’s estimated that around 50% of food purchasing decisions are made at the point of sale, so let’s give consumers the information they need to make better choices.
Alan Barclay, PhD is a consultant dietitian. He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of more than 30 scientific publications, and author/co-author of The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).