Influence of life-prolonging dietary restriction on intestinal vitamin A absorption in mice

Abstract

We studied influences of life prolonging dietary restriction on the absorptive capacity of the small intestine for the lipid micronutrient, Vitamin A. Using a well established intestinal perfusion technique, we measured the vitamin absorption rates in vivo in male mice fed regular laboratory chow (LC) ad lib, female mice on 95 kcal/week of a semipurified diet (designated “N” for normally fed), and female mice restricted to a 55 kcal/wk diet fed four days per week (R). The absorption rate of vitamin A was the lowest in LC mice and highest in R mice. Both at 6 and 26 months of age, R mice absorbed significantly more vitamin A than did the N mice. For example, at 6 months, R mice absorbed 10696 pmol/100 cm/hr while N mice absorbed only 7986 pmol/100 cm/hr (p<.01). Thus, dietary restriction increased the absorptive capacity of the small intestine for the lipid micronutrient vitamin A. The mechanisms responsible remain unknown, but could involve changes in the unstirred water layer resistance or in the lipid cell membrane of the enterocytes.