A proposal to redefine the internationally accepted definition of what constitutes “dietary fibre” was questioned in an address by senior CSIRO nutritionist Dr David Topping to the US Institute of Food Technologists’ Annual Meeting in Chicago.

Dr Topping will argue that the definition of dietary fibre should be broadened to include resistant starch – a form of starch that behaves in a very similar way to many traditional fibre components but is found in only small amounts in highly processed grains.

“Resistant starch shows all the characteristics of dietary fibre,” Dr Topping says. “It is not digested in the stomach, but passes on to the colon where it is fermented, promoting healthy digestive bacteria. Research at CSIRO and elsewhere has shown that resistant starch has significant benefits for bowel health.

“A broader definition than that proposed for dietary fibre is needed because of a greater understanding about the wide range of food components that act as fibre in the body, with their respective benefits for heart and digestive health.

“It will mean consumers will be able to eat a wider range of foods to meet their daily fibre needs as well as gain the additional health benefits offered by food components such as resistant starch.”

For the last six years nutritionists around the world have been working on a new definition of “dietary fibre” for the CODEX Alimentarius Commission – an international organisation working under the auspices of the World Health Organisation and the Food and Agriculture Organisation, which prepare model food regulations, both for individual countries to follow and to regulate trade.

The proposed new definition includes only “intrinsic plant cell wall polysaccharides”, or material from cell walls, particularly from fruit and vegetables, as dietary fibre.

“The health benefits of fruit and vegetables are well known, but there is also now good evidence to support the physiological effect and benefits of a number of other ’fibre-like’ food components such as resistant starch,” Dr Topping says.

“Because of the wealth of evidence showing the benefits of these other fibre-like components, CSIRO has set up a breeding program to develop new grain varieties with enhanced levels of soluble fibre, insoluble fibre and resistant starch.

“So far we have a new variety of barley - BARLEYmax™, which is a very high source of dietary fibre, has significant levels of resistant starch and also produces foods with a low Glycaemic Index.

“Clinical trials have shown very favourable effects on important measures of bowel health.”

Dr Topping was invited to present the case for the wider definition of dietary fibre at the United States Institute of Food Technologists Annual Meeting to support the many international nutritionists who believe a broader definition of dietary fibre is needed.

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