Serum vitamin B12, serum and red cell folates, vitamin B12 and folic acid binding proteins in women taking oral contraceptives.

Serum and red cell folate, FABP, serum vitamin B12 and vitamin B12 binding proteins were determined in 20 women taking oral contraceptives continuously for at least one year. Studies were also performed on 50 apparently healthy women with history of never taken or not taking oral contraceptives for at least one year as a control group. Serum vitamin B12 level, UBBC and TBBC in women taking oral contraceptives were slightly but not significantly lower than those of the control group. TCI and TCIII increased with a decreased TCII, so that UBBC was within the normal limit. Serum folate was non-significantly lower while red cell folate was significantly lower in the oral contraceptive group than those of the control group. However, all cases of the former showed red cell folate over 200 ng/ml. A highly significant increased serum FABP was demonstrated in the women taking oral contraceptives. This was probably due to the increased synthesis of the FABP in order to bind more folate from the low serum folate and the hormonally induced stimulation.