The influence of food additives and related materials on lower bowel structure and function.

Food additives, drugs, and other chemicals are known to influence the lower gastrointestinal tract under some defined conditions, resulting in morphological alterations in the mucosa and other tissues, deranged absorption and excretion of nutrients, and, in some cases, injury to other organs and tissues as a secondary phenomenon. Generally, in rats, hamsters, and dogs, there is increased absorption and urinary excretion of calcium, soft stools or diarrhea, and cecal enlargement. In the rat, hamster, and dog, renal lesions accompany the hypercalcemia and elevated excretion of calcium. These signs, symptoms, and lesions are typical of exposure to sugar alcohols (sorbitol, mannitol, xylitol, lactitol), lactose and caramel, some of the chemically modified food starches, and synthetic polydextrose. Soft stools and diarrhea, as well as cecal enlargement and variable hyperplasia of the colon mucosa, occur frequently when substances are absorbed incompletely in the small intestine and subjected to microbial metabolism in the cecum and colon. The remarkable cecal enlargement, mucosal hyperplasia and, when present, colonic mucosal hyperplasia are reversible, even when long-standing. Renal lesions are reversible only if exposure is of short duration, before significant mineralization and scarring has occurred. Morphological and functional anomalies associated with some of these substances are described and illustrated.