Plasma, leukocyte, and platelet ascorbic acid levels are decreased in women ingesting oral contraceptive steroids. Studies have shown that it is the estrogenic component of the oral contraceptive agents that is associated with the decresased ascorbic acid concentrations. Urinary excretion of ascorbic acid does not appear to be increased by the steroids. Although serum levels of copper are increased by estrogens and oral contraceptives, ascorbic acid catabolism does not appear to be increased (unpublished). Our preliminary data on tissue uptake of ascorbic acid suggest that changes in tissue distribution are one possible answer for the observed effects of the steroids on blood levels of ascorbic acid.
PIP: Plasma, leukocyte and platelet ascorbic acid levels have been shown to decrease in in women using oral contraceptives (OC). Supplemental ascorbic acid therapy ranging from 50-200 mg/day showed no difference between the values for supplemented and nonsupplemented OC use. Measurement of plasma ascorbic acid after supplementation with 500 mg ascorbic acid/day for 14 days showed that adequate supplementation to reach tissue saturation and maximum fasting plasma levels occurred in control subjects but not in OC users. Other studies indicated that when women were maintained for 75 days on high ascorbic acid intake, the plasma levels in OC users were lower than in controls. Studies in humans and animals suggest that the estrogen in OCs cause decreased plasma and tissue levels of ascorbic acid. Women taking oral progestin (.35 mg daily norethisterone) and depot progestin (150 mg medroxyprogesterone acetate im every 3 months) had similar leukocyte plasma and platelet levels of ascorbic acid to controls. 625 mg daily of conjugated estrogens showed lower plasma and leukocyte levels than controls. Whereas increase of urinary excretion of ascorbic acid during OC therapy has not been shown, an increase in serum copper levels has been shown under OC use and estrogen influence. It is suggested that an increased catabolism of ascorbic acid accounts for the decreased plasma and tissue levels in humans and animals with estrogen or OC steroids. Other unconfirmed or disputed suggestions include decreased absorption, changes in tissue distribution and decreased levels of reducing compounds. Tissue uptake patterns in steroid-treated animals appear altered suggesting that changes in tissue distribution may be associated with observed changes in ascorbic acid blood levels in OC users.