|December 2005||National Research Flagship||www.csiro.au|
the fibre gap
The type of fibre we eat may be far more important than the quantity alone.
This message was presented by a Senior Research Scientist with CSIRO Food Futures and Preventative Health Flagships, Dr David Topping at “Making Fiber Irresistible!,” a conference held in Chicago recently.
According to Dr Topping, some western populations have low fibre intakes, which not only affect 'regularity' but also can heighten risk for several non-infectious diseases.
The minimum threshold for regularity in adults is about 20-25 grams of dietary fibre a day. This is the range recommended in Australia in the most recent dietary recommendations published in 2005. However, most Americans get only 15g or so of fibre in their diets and this is much less than optimal. It is believed that Australians are consuming on average 25+grams of fibre per day, and while this is generally adequate, an increase in the type of fibre, specifically resistant starch, in the daily diet could bring considerable extra health benefits.
Dietary fibre comprises largely non-starch polysaccharides which resist human small intestinal digestion completely. This explains their excellent faecal bulking and laxative properties. Resistant starch is a fraction of starch which behaves like dietary fibre in resisting digestion in the small intestine. However, in the large bowel resistant starch (and a fraction of dietary fibre) are fermented by the resident bacteria.
Explaining the processes of the human digestive system, especially carbohydrates and resistant starch, Dr Topping reviewed how this fermentation may provide unique health benefits, focusing on three areas: improving bowel function and lowering the potential cancer risk associated with high-protein and low-carbohydrate diets; quicker recovery from infectious diarrhoea, for example, in disaster areas or war zones; and better absorption of minerals like calcium.
Increases needed in dietary fibre
The average fibre intakes are too low to obtain the expected benefits and need to be increased in the USA and for some people in Australia, according to Dr Topping. However, resistant starch (RS) is emerging as an even more important bowel health promoter than non-starch polysaccharides.
To address the problem of the low intake of RS in the US, Australia and other advanced countries, CSIRO is working actively to develop new high RS grains and foods to meet the need for greater RS consumption. This is being done through the Advanced Genetics research theme in the Food Futures Flagship.
The Food Futures Flagship is developing novel wheat varieties to meet the community's emerging health needs. These high RS wheats produce nutritionally significant levels of RS and can be incorporated into breads, cereals and other foods.
The Flagship's research in this area is an example of the successful collaboration of multi-disciplinary scientific expertise drawn from CSIRO Human Nutrition and CSIRO Plant Industry and, Food Science Australia, a joint venture between CSIRO and the Victorian Government.
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The Food Futures Flagship is a CSIRO initiative and part of the National Research Flagships program that aims to deliver scientific solutions to advance Australia's most important national objectives. One of the largest scientific initiatives ever mounted in Australia, it aligns closely with the Federal Government's National Research Priorities. The initiative brings together our national research resources to deliver breakthroughs in fields ranging from healthcare to light metals and the environment.
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