Broadening the definition of ‘dietary fibre’

The need to redefine the definition of "dietary fibre' was considered yesterday, in an address by senior CSIRO nutritionist Dr David Topping to the US Institute of Food Technologists' annual meeting in Chicago.

Topping argued that the definition of dietary fibre should be broadened to include resistant starch, which behaves in a very similar way to many traditional fibre components and is found in only small amounts in highly processed grains.

"Resistant starch shows all the characteristics of dietary fibre," said Topping. "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.

"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.

The proposed new definition includes only "intrinsic plant cell wall polysaccharides', 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.

CSIRO has already started a breeding program to develop grain varieties with higher levels of 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," said Topping.

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