Changes in gastrointestinal function attributed to aging.

There are numerous reports in the literature of impaired gastrointestinal function with aging. However, most gastrointestinal functions remain relatively intact because of the large reserve capacity of the intestine, pancreas, and liver. Clinically important changes in gastrointestinal function with aging in human include decreased taste thresholds, hypochlorhydria due to atrophic gastritis, and decreased liver blood flow and size. Increased absorbability of lipids and large size molecules has been demonstrated in aging animals, but this has not been studied in humans. Nutrients with impaired gastrointestinal bioavailability in aging include dietary B-12, calcium carbonate, and ferric iron in atrophic gastritis; calcium, zinc, and possibly carbohydrate in a mixed meal. The implications of these changes for health maintenance and chronic disease in elderly people are in need of study.