Intakes of dietary fiber, oligosaccharides, and other indigestible sugars
Vegetarians tend to have higher fiber intakes than omnivores. The typical intake of dietary fiber in North America and northern and central Europe is about 15 g/day. In Scandinavia and Italy, fiber consumption is 20–30 g/day, whereas in African countries such as Uganda, Kenya, Malawi, and Nigeria intakes may be as high as 50 g/day or more. Naturally occurring oligosaccharides are consumed in legumes, onions, fennel, chicory, and similar foods. Intakes in Western countries are probably up to 2–4 g/day. Fructo- and galactooligosaccharides are now being added to certain “functional foods” in a number of countries, and intakes from such sources may increase substan-tially (up to 10–20 g/day). Many kinds of indigestible or partially digested carbohydrates are entering the food supply in dietetic, diabetic, or functional foods, including sugar alcohols (polyols, e.g., sorbitol, man-nitol, lactitol), polydextrose, resistant starch, hydroge-nated starch, and other chemically modified starches and carbohydrates. Thus, the total amount of carbo-hydrate entering the colon could become very sub-stantial for people using these foods. Individually, these ingredients are generally recognized as safe, and evidence from populations consuming 50 g and more NSP per day suggests that the colon has the capacity to adapt to large increases in the load of carbohydrate. However, safe upper limits of intake are unknown and the health implications of an increased supply of a wide range of carbohydrates to the colon are currently based on inference rather than scientific data.