Tolerance of high fibre supplementation among participants in a randomised trial to reduce cancer risk among Alaska Native peoples: Alaska FIRST

Describing the epidemiology of colorectal cancer (CRC), Burkitt (1971) emphasised the increased incidence among developed, industrial populations consuming a more refined diet and proposed dietary fibre as the key to the lower CRC incidence noted in underdeveloped countries with less refined diets. Noting the increased incidence of CRC among Alaska Native (AN) peoples and seemingly low presence of fibre in some AN diets, investigators with the University of Pittsburgh and the Alaska Native Tribal Health Consortium proposed to test whether large amounts of fibre contained in a dietary supplement could lower CRC risk. We describe supplement tolerance as reported by AN participants completing a 4-week supplementation trial, which added 44.5 grams per day (g/d) total fibre (23.7 g/d resistant starch (RS)) to the diet of those assigned to the intervention arm and 1 g/d total fibre to those assigned to the control arm. Tolerance of the high fibre supplement would play a key role in protocol adherence as well as any recommendations for future use by the broader population. In this study, the daily RS intervention containing 44.5 g/d additional dietary fibre produced more flatulence than usual but fewer other symptoms were consistently reported compared to the digestible starch (DS) control.