Have you had your sorghum? Gluten-free Weet-Bix helps combat diabetes
Curtin researcher and food scientist, Dr Stuart Johnson, discovered that a grain used mainly in animal feed in Australia contains properties which not only provide nutritional benefits to humans, but also have the potential the help combat chronic conditions, which are currently the leading cause of illness, disability and death in Australia[i].
One of the world's fastest growing chronic conditions is type 2 diabetes mellitus, for which there is no cure. Globally, one in 11 adults (415 million people) has diabetes. It's the fastest growing chronic condition in Australia and around the world, with type 2 diabetes, commonly associated with lifestyle factors such as diet, accounting for 85 per cent of all cases[ii].
Sorghum is a grass or cereal grain similar to wheat. Originating in Ethiopia, it's used in Africa for a range of purposes including as a staple food and in fermented beverages such as beer. Globally, it's the fifth most produced grain behind wheat, maize, rice and barley, however in Australia, it's considered a low-value grain predominantly used in animal feed.
Dr Johnson's findings revealed that although its nutritional composition is similar to wheat, sorghum is far easier to digest and is abundant in bioactive phytochemicals.
The project was an Australian Research Council-funded collaboration between the University of Wollongong and industry partner organisation Sanitarium Health and Wellbeing. Titled Slowly digestible, high antioxidant sorghum: a new wholegrain food paradigm to help combat type 2 diabetes, it commenced in 2011 and spanned four years.
The project featured three key stages. The first phase found brown and red sorghum to contain much higher levels of antioxidants compared to wheat (Johnson et al, unpublished), and therefore a higher capacity reduce oxidative stress – a key contributor to the progression of symptoms of type 2 diabetes and other chronic diseases, particularly in those who are overweight or obese.
The second phase involved the development of sorghum-based Weet-Bix at Sanitarium using white, red and brown sorghum grains and the conventional wheat grains. These flaked breakfast cereals were lab-tested to determine their antioxidant capacity, which, like the raw grains, was higher in the red and brown sorghum-based products than white sorghum and wheat-based[iii].
The final stages of the project involved 'post meal trials' conducted at the University of Wollongong using wheat-based Weet-Bix and three experimental versions made from white, brown and red sorghum respectively. Forty participants were monitored for appetite suppression, antioxidant capacity of their blood serum and their blood glucose levels over a two or three-hour period, with testing occurring every 15 to 30 minutes.
The health implications of the research are clearly demonstrated in the results, which showed that sorghum-based Weet-Bix gave high appetite suppression, and thus may help reduce overall energy intake and obesity risk, by significantly decreasing hunger and increasing the feeling of satiety in the participants after the meal.
Participants reported significantly lower hunger levels and significantly higher 'fullness' after eating the sorghum-based product.
Hormone levels associated with appetite suppression were simultaneously measured over the same timeframe. The levels of glucagon-like peptide 1 (GLP-1) and gastric inhibitory peptide (GIP) were significantly higher in the blood of the participants after the sorghum breakfasts (GLP-1, 72.7-104.2 pM.min; GIP 7892 – 10155 pg/mL.min) than the wheat (GLP-1, -30.7 pM.min; GIP 7200 pg/mL.min). The red sorghum gave the highest value of these two appetite supressing hormones among the sorghum breakfasts.
For any food to provide health benefits in the long term it needs to be palatable to the consumers. Sanitarium Health and Wellbeing determined that the red sorghum flaked breakfast cereal was highly palatable to their test consumers (Sanitarium Health and Wellbeing, unpublished).
A parallel post-meal study within the project on wheat-based pasta made from wholegrain sorghum flour found that the red sorghum pasta resulted in lower blood glucose, significantly higher appetite suppression response after the meal4 and notably lower markers of oxidative stress in the blood5[iv]. All of these findings support the potential of red sorghum-based foods for protection against type 2 diabetes and other related metabolic diseases.
The research project informed the development of the first ever staple food made almost entirely from red sorghum whole grains: Sanitarium Gluten Free Weet-Bix.
A Weet-Bix factory in Carmel, Western Australia, was converted into a dedicated Gluten Free Weet-Bix factory, to eliminate the risk of wheat contamination.
The product label claims the new line is 96 per cent wholegrain, containing three times the antioxidants of oats, low sugar, high iron, vitamins B1, B2 and B3, a source of dietary fibre, a source of magnesium and high in folate.
Launched in 2014 in Coles, Woolworths and independent retailers, Gluten Free Weet-Bix proved a major coup for Sanitarium, becoming the highest penetration gluten free cereal and segment leader within six months of launch [v].
[i] Australian Institute of Health and Welfare 2016.
[ii] Diabetes Australia: http://www.diabetesaustralia.com.au
[iii] Khan, I (2014), Health Potential of Sorghum-Containing Pasta: In Vitro and Clinical Studies. PhD Dissertation, Deakin University, Melbourne, Australia.
[iv] Khan, I., Yousif, A. M., Johnson, S. K. & Gamlath, S. 2015. Acute effect of sorghum flour-containing pasta on plasma total polyphenols, antioxidant capacity and oxidative stress markers in healthy subjects: A randomised controlled trial. Clin. Nutr. vol. 34, pp. 415-421.
[v] Marketing Mag https://www.marketingmag.com.au/hubs-c/weet-bix-case-study
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This story is from A Decade of Impact
A Decade of Impact is a series that showcases some of Curtin's most impactful research projects in recent years. The chosen research projects are examples of how Curtin translates its research into economic, environmental and social impact.
Nik Malane
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