Factors in aging that effect the bioavailability of nutrients.

Until a few years ago, little was known about bioavailability of micronutrients in elderly humans. It was assumed by many basic investigators and geriatricians that malabsorption of both macronutrients and micronutrients was a common problem among elderly persons. We now know that this is not the case; elderly persons who malabsorb macronutrients do so because of disease, not because of age. This report will be divided into three sections. The first section focuses on the general principles of absorptive processes in elderly persons. The second section focuses on the bioavailability of specific micronutrients in elderly persons, with specific examples of "problem" nutrients. The third section lays out a proposed research agenda for studying the bioavailability of nutrients and other active components of dietary supplements in elderly persons.