Dr Alan Barclay
The ‘new’ Australian Dietary Guidelines, carbs and GI
The draft (there’s still time to comment) Australian Dietary Guidelines are a definite improvement on earlier versions. But they represent a mix of progress and lost opportunities and we must do much better if we are going to tackle the diabetes and obesity epidemics. We need to get them right because as Drs Willett and Ludwig point out (commenting on the US equivalent), they have a major impact on our foods and diets – government food policies, food and health programs and food regulations generally comply with them, even though the average consumer has never heard of them. Here, I am simply going to focus on a couple of key issues regarding carbs because they focus on the health problems associated with eating and drinking too many added sugars, but ignore or confuse the role of added refined starches.
Added sugars The Guidelines advise people to limit their intake of sugar-sweetened drinks. While there is some evidence that people who are obese should limit their intake of sugar sweetened beverages, there is evidence that Australians are drinking less of them, but we are still gaining weight and developing type 2 diabetes. So something else is happening ...
Starchy foods Here they take a ‘good cop’ ‘bad cop’ approach. They generally opt for the out-dated term ‘complex carbohydrate’ instead of ‘starch’, the term recommended by the World Health Organisation since 1997. This is confusing and misleading as most people don’t know that starches are complex carbohydrates – they are one and the same. Complex carbohydrates (specially wholegrain ones) are the good cops and there’s lots about their health benefits in the draft Guidelines. Starches are the bad cops and this is the term they choose to use when discussing dental caries or other health problems, e.g.: ‘Historically, the prevalence of dental caries has increased when dietary patterns have changed to include more added sugars and foods containing refined starches.’ And ‘fermentable carbohydrates (both sugars and starches) are a substrate for bacteria such as S. mutans and S. sobrinus, which increase the acid-producing potential of dental plaque’.
Glycemic Index Interestingly, every Australian Guideline in the draft has a statement comparable with the 2010 Dietary Guidelines for Americans. One area where they have very obviously borrowed straight from the US is with the glycemic index. They say: ‘The review for the US guidelines also found strong and consistent evidence that glycaemic index and/or glycaemic load are not associated with body weight and do not lead to greater weight loss or better weight management. These factors were not included in the literature review to inform the revision of these Guidelines.’ However, in their critical review of the new American Dietary Guidelines, Drs Willett and Ludwig state ‘Furthermore, the quality of carbohydrates, as characterized by their glycemic index, is dismissed as unimportant, whereas we believe the evidence strongly suggests the opposite.’
We agree with Drs Willett and Ludwig: there is in fact level 1 evidence (the highest level) that low GI diets help people lose more weight and in particular body fat than regular healthy diets, and level 2 evidence that low GI diets help people keep the weight off for longer. And of course it is short-sighted to focus just on body weight with a diabetes epidemic on our doorstep. The GI is widely accepted around the world by diabetes associations as a useful dietary tool for people with diabetes to help them manage their blood glucose levels.
We will be commenting on these draft Guidelines and we urge you to do so as well. They offer Australia an opportunity to lead the world by:
- Discarding an outdated term like ‘complex carbohydrate’ which does not describe how carbohydrates behave in our bodies, and
- Encouraging the consumption of low GI carbohydrate foods to reduce rates of overweight, obesity and type 2 diabetes.
For more information about the GI Symbol Program
Dr Alan W Barclay, PhD
Chief Scientific Officer
Glycemic Index Foundation (Ltd)
Phone: +61 (0)2 9785 1037
Mob: +61 (0)416 111 046
Fax: +61 (0)2 9785 1037