Vegetable fibre value ‘more than bran’

Press, 24 April 1986, Page 33

Vegetable fibre value ‘more than bran’

By

IAN WILLIAMS

of AAP through NZPA Adelaide It seems that Mum was right all along — eat up all those fruit and vegetables. A Commonwealth Scientific and Industrial Research Organisation study, said to be a big development in the understanding of nutrition, has recommended that Australians eat more fruit and vegetables and cut down on wheat bran. Scientists with the division of human nutrition in Adelaide have discovered fruit and vegetables are a far more important source of fibre than wheat bran which is good for constipation. The studies, in collaboration with Dr Michael Lawson, of Adelaide’s Queen Elizabeth Hospital, call for a revision of the role of fibre in human nutrition. Researchers found that the fibre in wholegrain cereals, fresh fruit, and vegetables is far more beneficial than previously thought. Their research has shown that the fibre from fruit and vegetables and some cereals is broken down by bacteria in the gut and provides a source of energy. People could use plant fibre in the same way as cattle and sheep. Because bran could not be broken down by the body and provided only roughage, people wrongly thought wheat bran was the best if not the only kind of fibre. The researchers found that a mixed high-fibre diet lowered cholesterol levels to the same extent as could be achieved with some drugs. The C.5.1.R.0. research has shown that fruit and vegetable fibres, which are broken down by bacteria in the gut, are most effective in bringing about these changes. Bran was not broken down by gut bacteria, and had no effect on blood cholesterol and glucose levels. Mail surveys conducted by the C.5.1.R.0. in Adelaide found that bran was one of the most popular

dietary supplements with about 22 per cent of women and 12 per cent of men using it at least once a week. The surveys dealt specifically with bran supplements and not branbased breakfast cereals or other sources of bran. The scientists believe usage of bran in ail its forms to be far higher. “People generally add bran to a diet that is low in fibre,” said a C.5.1.R.0. scientist, Dr David Topping. “By eating more fruit and vegetables their diet will be changed to one which is higher in fibre and generally lower in saturated fats.” Most Australians have a diet too high in saturated fats and protein and low in fibre, factors thought to be implicated in the development of bowel cancer, he said. One in every 20 Australians would develop cancer of the large bowel and 60 per cent of them would die within six years of diagnosis.

Dr Topping said the research had shown that fibre, other than bran fibre, fermented in the large bowel in a manner very similar to that which occurred in the forestomach of sheep and cattle. “This process creates large quantities of volatile fatty acids and these acids provide energy relatively slowly unlike the dietary fats and simple sugars, which are rapidly absorbed and used by the body,” he said. “The importance of these acids has been greatly under-estimated. They are absorbed by the gut and extensively used by the body for energy. “One of these acids appears to be an energy source, while another may inhibit the growth of malignant cells in the large bowel. “All fruit and vegetables, particularly vegetables of the cabbage family, are good sources of fibre, though lengthy cooking tends to destroy the important fibre constituents."