Commentary: the rough world of nutritional epidemiology: does dietary fibre prevent large bowel cancer?

contradictory messages, so it can be comforting to cling to advice that appears constant. One concept on which the nutritional cognoscenti are united is the value of eating a diet rich in fibre.' 1 This quote from a doctor writing in a British broadsheet newspaper illustrates many of the problems faced by nutritional epidemiologists and health practitioners who try to determine the health damaging and health promoting aspects of a population's diet and provide appropriate dietary advice to its members. 1 No doubt this doctor will be frustrated if he reads today's volume of the International Journal of Epidemiology (IJE) in which the findings of a prospective cohort study by Mai et al. suggest that diets rich in dietary fibre are not protective against colorectal cancer. 2 Burkitt is credited with first proposing that dietary fibre was protective against colorectal cancer and other gastrointestinal problems including diverticular disease and appendicitis. 3,4 However, discussions about the value of white (of low fibre content) and brown (of high fibre content) bread date back to antiquity. Interestingly, Hippocrates, in the 5th century BC, believed white bread to be more nutritious: 'Wholemeal bread cleans out the gut and passes through as excrement. White bread is more nutritious as it makes less faeces.' 5 In England the notion that wholemeal bread was good for health had emerged by the late 1500s, with Peter Stubs writing in 1585 'doe we not see the poore man that eateth browne bread healthe fuller, stronger, fayrer complectioned and longer living than the other that faredaintelie every day.' 6 In 1683 Tyron wrote a book about the value of wholemeal bread, stating that it was the most important way to a long and happy life. 7 In the US in 1837 Sylvester Graham wrote on the importance of wholemeal bread as a natural food, and to this day wholemeal bread in the States is known as Graham bread. 8 and fibre supplementation in prevention of colorectal adenoma recurrence: a randomised intervention trial. European Cancer Prevention Organisation Study Group. Menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer (United States). Wacholder S. Interpretation of energy adjustment models for nutritional epidemiology. 11 Wolk A, Manson JE, Stampfer MJ et al. Long-term intake of dietary fiber and decreased risk of coronary heart disease among women. Willett WC. Vegetable, fruit, and cereal fiber intake and risk of coronary heart disease among men. …