‘A number of the most common diseases in Western society are rare and in some instances almost unknown in communities minimally influenced by modern Western culture. The dietary change most consistently associated with increased prevalence of these diseases is a reduction in the amount of dietary fibre consumed. Hypotheses have been postulated to endeavour to explain the relationship between these diseases and fibre-depleted diets. In some, for example constipation and diverticular disease, the evidence is generally accepted as almost conclusive. Others require further testing, but for some no alternative hypotheses consistent with epidemiological evidence have been formulated’.