Dietary fibre may be of little benefit and in fact may in some cases increase the risk of disease, according to a UK researcher. This is particularly true of fibre supplements rather than fibre in its more natural form of fruit and vegetables.
An assessment of the value of fibre is published this morning in the journal Gut. Instead of protecting us from colon cancer, some fibre and fibre supplements could increase our risk of developing it, said Dr Robert Goodlad of the Imperial Cancer Research Fund.
Dr Goodlad cited a number of recent human and animal studies that raised doubts about fibre.
"The implications of this are obviously a cause of some concern but most pundits would appear to be in a state of denial."
Western society has become wedded to the idea that fibre is good, so much so it is now part of public health promotion in most developed countries including the Republic. It dates back to the 1970s and the discovery by Northern Irish missionary surgeon Dr Denis Burkitt that rural Africans had much less colon cancer than Westerners.
The assumption was that the benefits were in the fibrous parts of high-fibre foods. Dr Goodlad suggests, however, that it might not be the fibre but the range of minerals and vitamins in these foods which deliver a health benefit.
The foods we recognise as high-fibre are rich in active plant materials, "the so-called phytoprotectants", he said. Products that boost fibre intake and leave out these useful materials "give us the potential to have the worst of both worlds".
A high-fibre diet and fibre supplementation are not the same. "There is now a potential for adverse effects if fibre intake is boosted by consuming various purified supplements, which are now available as "functional foods", he said.
"In summary, the actions and interactions of diet and the gut are complex and one should be wary of over-simplistic theories."
Dr Goodlad does not abandon the value of fibre entirely. "The usual advice to have a balanced diet and everything in moderation is still appropriate." Exercise and avoiding obesity are also important.
"I still advocate eating plenty of fibre but only if it comes from the fibre-rich foods and would favour fruit and vegetables over cereal fibre."
