June 24, 2016

Researchers unlock market potential of gluten-free sorghum

Nutritionists discover untapped potential of Australian-grown grain in reducing obesity.

Researchers at the Illawarra Health and Medical Research Institute (IHMRI) and UOW have helped to unlock a new market for sorghum by conducting a clinical trial which showed that the gluten-free grain, which is related to millet, increases satiety or the feeling of fullness between meals. This was backed up by a second study showing that sorghum may have a role in reducing overweight and obesity when eaten regularly as part of a weight-reducing diet. 

The studies were led by Advanced Accredited Practising Dietitian Anita Stefoska-Needham who was encouraged to pursue a PhD on sorghum-based foods and their potential to assist in the prevention of chronic disease by her supervisor, Associate Professor Eleanor Beck, and one of Australia’s leading experts on nutrition and dietetics, Senior Professor Linda Tapsell AM. 

As a dietitian, Anita was aware that sorghum was a gluten-free whole grain but, as there were virtually no sorghum-based food products on the market at the time, it did not feature in her usual dietary advice. A literature review revealed that sorghum, which is the third largest crop in Australia and widely cultivated globally due to its adaptability to arid conditions, is predominantly used as animal feed in Australia. 

However, the grain is regularly eaten in countries like Africa and is ideal for human consumption as it provides vitamins, dietary fibre, antioxidant compounds and slowly-digestible starches which can enhance satiety between meals. 

It was clear that sorghum not only represented an untapped human food source locally, but had significant market potential, particularly in developed countries where there is great interest in ‘naturally functional’ food products. 

Thanks to an Australian Research Council Linkage Project grant, Anita was able to work with industry partner, Sanitarium Health and Wellbeing Australia, as well as collaborators at Curtin University to formulate flaked breakfast cereal biscuits made from white, red and brown sorghum whole grains. 

The biscuits, which are similar to a popular wheat product that many Australians consume at breakfast, were used in an acute feeding study with 40 subjects (20 males and 20 females), each of whom attended the unit on four occasions after a 12-hour fast. 

At baseline, they consumed 50 grams of one of the three different flaked sorghum biscuits, or a whole wheat control biscuit. The trial not only investigated subjective satiety, but changes to glucose, insulin and several appetite-regulating gut hormones. 

As recently reported to the journal, Molecular Nutrition and Food Research, the results confirmed that a sorghum-based breakfast cereal enhanced acute subjective satiety and increased satiety-enhancing hormone levels over four hours after eating, compared to a whole wheat-based control. Cereal made from red sorghum, a variety rich in anthocyanin flavonoids, elicited the greatest overall acute satiety-enhancing response. 

To better understand if these satiety effects could be translated into longer-term effects on food consumption and thereby weight, Anita then conducted a randomised controlled trial with 60 overweight and obese participants who were randomly allocated to either a sorghum (intervention) or whole wheat (control) group, receiving 45g of flaked cereal biscuits to include daily in their prescribed weight-reduction diets for 12 weeks. 

Both groups experienced significant weight loss and a general improvement in all clinical measures, including fasting glucose, insulin, cholesterol and key inflammatory biomarkers, indicating that sorghum can be part of a healthy diet. 

“Findings from both these trials indicate that sorghum whole grain is a promising novel ingredient in foods targeting satiety as an adjunct for weight control,” said Anita. 

“The findings not only provide new knowledge that may improve health outcomes for consumers, but they also contribute to developing and growing the sorghum industry globally.” 

Supported by this body of work, a sorghum-based food product has been successfully launched into the market by Sanitarium Health and Wellbeing Australia; a business decision supported by scientific evidence. 

“Multinational corporations and smaller entrepreneurial food companies now need to invest in launching sorghum-based product formats with the potential to become popular in these markets,” concluded Anita.