Effect of oral contraceptives on intestinal folate conjugase activity and folate absorption in rats

To study whether oral contraceptive agents (OCA) may interfere with intestinal absorption of folate polyglutamates by inhibiting the activity of intestinal folate conjugase, female rats weighing on the average 230 gm received either a stock diet and OCA daily for a 6-week period or the stock diet without OCA. The animals receiving the OCA gained 50% less of their original body weight than the controls. There were no significant differences in the in vivo absorption of either folate monoglutamate or folate pentaglutamate between the controls and the OCA-administered animals. The absorption of folate pentaglutamate was lower than that of folate monoglutamate in both groups of rats, but the difference was not statistically significant (p greater than 0.05). As in the case of the two forms of folate absorption, no significant difference was found in intestinal folate conjugase activity between the two groups of animals. These findings indicate that intestinal folate conjugase activity and the absorption of both folate monoglutamate and pentaglutamate are not altered by oral contraceptive administration to female rats.