Carbohydrate Intakes – high, low, or irrelevant?
Did you see the recent headlines surrounding the health risks of low carbohydrate diets? These were the result of a symposium hosted by ILSI SEAR Australasia in conjunction with the Grains & Legumes Nutrition Council™ held on Tuesday 19th March 2013. This event brought together a panel of highly accomplished experts to discuss the topic of carbohydrates and health. Here’s a summary of the three lead presentations as well as an outline of each of the topics discussed at the event.
Professor Peter Williams, of the University of Canberra, set the scene for the day by outlining trends in carbohydrate intake and providing an overview of the health effects of various levels of carbohydrates intake. Australia’s National Health and Medical Research Council (NHMRC) suggests Australians should eat between 45-65% energy from carbohydrates. The most recent data suggests Australians are consuming 46% energy from carbohydrate, compared to countries around the world where intakes range between 38-79%.
Prof Williams cautioned that percentage energy intake is only part of the story and that the total amount of carbohydrate and total energy consumed from carbohydrate are important considerations for health. Prof Williams outlined that higher intakes of dietary fibre and whole grains appear to have health benefits, however low carbohydrate diets which may restrict whole grains and fibre rich foods are often promoted in the general public for short term weight loss.
Notably, a recent meta-analysis found that long term exposure to low carbohydrate diets was associated with a higher risk of death, indicating that low carbohydrate diets in the long term may pose health risks. With the popularity of ‘low carb’ diets, it was not surprising this research received media attention. Here is a link to an interview Prof Williams provided on the day of the symposium. Prof Williams concluded that not all carbohydrates are the same and that food based evidence is best to guide dietary recommendations.
Professor Manny Noakes, of the CSIRO, elaborated on the potential risks and benefits of low carbohydrate diets. Based on the current evidence, Prof Noakes suggested that while low carbohydrate intake (less than 100g) appears to be effective for weight management, these diets are often associated with high saturated fat composition, which may have a negative impact on heart health.
Interestingly, Prof Noakes suggested that some components of whole grains may in fact promote fat loss, as there is a body of scientific evidence which suggests that higher grain intakes (particularly whole grains) is associated with reduced body weight. Prof Noakes concluded that the inclusion of moderate amounts of carbohydrate in the form of high fibre whole grains, low glycemic index (GI) grain foods, dairy and fruit is optimal for weight loss and nutrient intakes.
Dr Alan Barclay, of the GI Foundation and Australian Diabetes Council, addressed the risks and benefits of high carbohydrate intakes. Dr Barclay summarised a recent review which found that high fibre intake is associated with lower risk for obesity, type 2 diabetes, cardiovascular disease and colorectal cancer.
Reflecting the current debate around sugar intake, Dr Barclay discussed the latest research on dietary sugars and body weight conducted for the World Health Organization (WHO), which found that while sugar-sweetened beverages (like soft drinks and cordial) were linked to weight gain, changes appeared to be related to energy intakes and exchanging sugars for other carbohydrates (i.e. starches) was not associated with weight change.
Dr Barclay went on to present evidence which suggests that GI and glycemic load (GL) are stronger predictors of disease risk including obesity, diabetes and heart disease. In conclusion Dr Barclay stated that rather than focusing on sugar or starch content of foods the evidence suggests that Australians need to lower the GI of their diet.
Dr Jane Muir, Monash University, spoke about the risks and benefits of fermentable carbohydrates (FODMAPs).
Dr Anthony Bird, CSIRO, spoke about the emerging area of research around prebiotic carbohydrates.
Mr Bill Shrapnel, Shrapnel Nutrition Consulting, and Dr Alan Barclay evaluated the current measures of carbohydrate quality.
Dr Louise Burke, of the Australian Institute of Sport, outlined the evolution of carbohydrate guidelines for sports performance.
Ms Nilani Sritharan, Cereal Partners Worldwide, described the challenges of translating the nutritional science into real foods that consumer will eat.
Ms Sarah Hyland, Colmar Brunton, spoke about consumer attitudes to carbohydrate intake.
Prof Amanda Lee, Queensland University of Technology, outlined the current consumer guidance on carbohydrate intake as outlined in the Australian Dietary Guidelines.
If you would like to read further on one or more of the topics discussed, see the presentations here.