Effect of age on poly- and monoglutamyl folacin absorption in human subjects.

Intestinal folacin absorption and mucosal conjugase activities were assessed in healthy male elderly (65-83 years) and young (20-29 years) human subjects. Luminal disappearance as measured simultaneously from the perfused jejunum of 3 mumol of both [3H]pteroylmonoglutamate [( 3H]PG-1) and pteroyl-[14C]glutamyl-hexaglutamate [( 14C]PG-7) as well as the urinary recovery of each isotope and mucosal conjugase activities were compared. Luminal disappearance of either [3H]PG-1 or [14C]PG-7 was not different for the two age groups (P greater than 0.05). The average (mean +/- SD) disappearance of [3H]PG-1 was 63 +/- 12% in the elderly and 67 +/- 6% in the young groups. In contrast, the disappearance of [14C]PG-7 averaged 51 +/- 6% in the elderly and 48 +/- 3% in the young group. Urinary recovery (percent in 48 hours) was not different for either isotope when the two age groups were compared (P greater than 0.05). The urinary recovery of 3H averaged 60 +/- 21% in the elderly and 59 +/- 13% in the young in contrast to 35 +/- 22% and 35 +/- 7% for 14C recovery in the elderly and young groups, respectively. Folacin conjugase activities measured at pH 6.5 and at pH 4.5 were not different between the groups (P greater than 0.05). The findings indicate that intestinal absorption of folacin and activity of folacin conjugases are not affected by the aging process.