Abstract
Riboflavin deficiency has been reported in older individuals. The cause of this deficiency is not known but could include a decrease in the intestinal absorptive capacity for riboflavin. Therefore, we examined the intestinal absorption of riboflavin in young (3 month) and old (26 month) rats. We used
in vitro
jejunal everted sacs. The kinetic parameters of riboflavin absorption disclosed apparent K
m of 0.37 and 0.43 μM and V
max of 37 and 38 pmole/g initial tissue wet wt/20 min in young and old rats, respectively. These data do not demonstrate an aging associated change in the intestinal transport capacity for riboflavin. If these results are extrapolated to man, it would mean that the deficiency of riboflavin found in the elderly is not due to its intestinal malabsorption. Therefore, other mechanisms must be sought to account for the deficiency of riboflavin seen in the elderly.