Working in Africa in the 1950s, Dr Dennis Burkitt discovered that few rural black Africans suffer from colon cancer. He attributed this to their relatively crude diet.
But the theory has never been substantiated. African average life expectancy then was only 40 years - cancer doesn't peak in Europeans until age 65; as the Africans moved into towns and adopted a Western style low-fibre diet their cancer rate did not change; and Mormons of Utah eating a low- fibre diet also enjoy a low incidence of colon cancer.
In 1990, the British Nutrition Foundation admitted that the hypothesis that fibre deficiency increased colon cancer risk was unsubstantiated, and the Seventh King's Fund Forum stated: "... cereal fibre does not offer protection against cancer...".
A 1991 Japanese study blamed soft faeces (bran softens faeces) for increased risk. In an Italian study in 1993, three teaspoons of sugar were found to double colon cancer risk. In Iowa, sugar and total carbohydrates were implicated in a study of 35,215 women in 1994.
In 1996 Dr Wasan and Dr Goodlad, of the Imperial Cancer Research Fund, writing in The Lancet, stated: "Until individual constituents of fibre have been shown to have, at the very least, a non-detrimental effect in prospective human trials, we urge that restraint should be shown in adding fibre supplements to foods, and that unsubstantiated health claims be restricted. ... Specific dietary fibre supplements, embraced as nutriceuticals or functional foods, are an unknown and potentially damaging way to influence modern dietary habits of the general population."
And there is no evidence that fibre reduces the risk of heart disease either.
BARRY A GROVES
Milton under Wychwood, Oxfordshire