Measurement of dietary fiber in a total diet study

Abstract A total diet study was undertaken to estimate human intake of chemical substances and nutrients. This work reports the dietary fiber content of 101 representative foods, collected at 6-month intervals from summer 1986 to summer 1988 in five main population centers across Canada. Four samples of each food were sent fresh or frozen to the central laboratory where they were mixed into composites. The composites were prepared as for consumption (raw and/or cooked), freeze-dried, ground, and stored until analysis. Dietary fiber was measured using a rapid gravimetric method. Results suggest that the dietary fiber values did not vary among seasons or cities. The dietary fiber content (g/100 g) ranged from 0.7 to 3.0 in fresh fruits and to 7.3 in dried fruits, from 0.7 to 2.4 in fresh vegetables, from 0.9 to 15 in breakfast cereals (excluding high-fiber bran cereals), and from 0.8 to 7.4 in other foods. Cooking of foods ( n = 10) tended to decrease the soluble/insoluble fiber ratio in some foods. Using the new data and the information from the 1971–1972 Nutrition Canada survey, the average dietary fiber intake of Canadians was estimated at 12.4 g per day.