Severe impairment of dietary folate utilization in the elderly.

Absorption of folates, vitamin B6, pantothenate, and riboflavin from a natural food source (yeast) and from synthetic folylmonoglutamate was studied in 24 elderly subjects (age range, 73 to 101 years) and in 12 healthy younger subjects (age range, 24 to 42 years). All subjects absorbed riboflavin, vitamin B6, and pantothenate from yeast. Ingested folypolyglutamates (the preponderant folates in yeast) proved to be a very poor source of folates for the elderly subjects, whereas synthetic folylmonoglutamate served as a good source. In the younger subjects, yeast was a significant folate source. It is suggested that the folate deficits so common in the elderly are caused by impaired ability to obtain folate from ingested foods. The resultant folate deficit may induce changes in the epithelial structure and enzyme secretion of the small bowel, which may further exacerbate folate malabsorption.