Wholegrain fibre linked to cancer prevention by Rada Rouse
GroundCover™ Issue: 39
A REVIEW of the scientific evidence linking wholegrain foods to a reduced cancer risk may give fresh impetus to an industry proposal for nutrient claims on breads and cereals.
CSIRO researcher Graeme McIntosh has found convincing evidence that regular consumption of wholegrain foods will protect against bowel cancer. Dr McIntosh, senior principal research scientist at the CSIRO's health sciences and nutrition laboratories in Adelaide, said pure fibre or cellulose may not by itself contribute much to health or cancer prevention.
However, cereal fibre was a marker for a complex range of beneficial micronutrients and phytochemicals believed to do an important antioxidant job. Phytates, for example, contained in the same outer layer of the grain as the fibre, have been shown in lab experiments to head off the development of induced cancer.
First wholegrain guidelines
The findings of Dr McIntosh's review were so strong that they prompted the Cancer Council NSW to issue Australia's first expert recommendation quantifying the amount of wholemeal or wholegrain food that should be consumed daily.
Cancer Council chief executive Andrew Penman said people should choose wholemeal or wholegrain for at least half of their daily servings of breads, cereals, rice and pasta. The Dietitians Association of Australia has backed the recommendation. Until now, the only public guidance on the issue has been a National Health and Medical Research Council recommendation to consume four serves a day of cereal-based foods.
But if Australians are to be urged to choose more wholegrain food, how are they to judge what's on offer on supermarket shelves?
The Cancer Council, along with the industry nutrition communication body Go Grains, believe the answer lies with a proposal for new nutrient claims that is now before the Australia New Zealand Food Authority (ANZFA). Go Grains is supported by growers and the Federal Government through the GRDC.
"We want to suggest to ANZFA that they actually introduce some criteria to help people identify what a whole grain food is," Go Grains manager Trish Griffiths said. "We are suggesting that if a product has more than 25 per cent wholegrain ingredients, it can be claimed as a 'source of wholegrain'; and if it has more than 50 per cent, it can be claimed to be a 'good source of wholegrain'."
The ANZFA administered voluntary code of practice on nutrient claims currently permits manufacturers to make claims for "high fibre" and "low fat" content if products meet specified criteria.
The Cancer Council NSW is backing Go Grains in The Cancer Council NSW is backing Go Grains in its submission, believing that there is no point issuing dietary guidelines if labels on cereal products are not consistent. Ms Griffiths adds that, without standardised labelling, consumers may not realise that some foods - such as rolled oats - are a wholegrain, or unrefined, product.
Dr McIntosh's review, which was commissioned by Go Grains and part-sponsored by the Cancer Council NSW, was recently published as a supplement to the Australian Journal of Nutrition and Dietetics. He found strong evidence for wholegrain protection against colorectal cancer, some evidence for protection against gastric cancer, but only weak evidence that wholegrain foods may be protective against lung, breast and prostate cancer.
Cutting risk almost in half
The risk of colorectal cancer may be reduced by up to 40 per cent if wholegrain or wholemeal foods are chosen regularly as part of a diet also rich in fruits and vegetables, Dr McIntosh said.
"There is a good case, based on recent dietary survey data, for recommending that Australians increase dietary fibre intake by 20 to 25 per cent, and this could best be achieved by substituting wholegrain and wholemeal foods for refined cereal foods in at least half of the recommended cereal servings," he concluded.