Relationship between the intake of high-fibre foods and energy and the risk of cancer of the large bowel and breast.

A recent analysis of Food and Agriculture Organization (FAO) data and mortality data has shown that not all fibre sources are equally protective against colorectal and breast cancers. We correlated the risk of cancers of the colon and breast with the intake of cereals, starchy roots, vegetables, fruits and total energy, either concurrently with the cancer mortality data, or from 20 years earlier. The patterns of the effects of cereals, starchy roots, vegetables and fruits were very different, with cereals and vegetables being protective against both cancers, fruit having no effect and starchy roots having a very weak and non-significant promoting effect. There is strong current interest in the protective effects of fruit and vegetables against cancers at a number of sites. Our analysis showed that only the current intake of vegetables was protective. Intake early in life seemed to offer no protection. The protective effect of cereals was manifest both early in life as well as for current intake for female breast and colorectal cancer, but only for the current period for male colorectal cancer. Calorie restriction, but only early in life, provides protection against all three cancers. Most advice on healthy eating, other than that for small children, is given to (and taken by) the senior age groups and these are the ones likely to benefit. In our study fruit intake was not correlated at all with the risk of either colorectal or breast cancers at either time period. Fruit is clearly more protective against cancers of the upper digestive tract and respiratory tract than against the cancers considered here.