Blood levels of homocysteine, folate, vitamin B-6 and B-12 in women using oral contraceptives compared to non-users

Background and objectives: To compare the levels of total homocysteine (tHcy), folate, vitamin B-6 and B-12, in women not using oral contraceptives (OC) vs. those using OC. Materials and methods: 219 healthy women were enrolled in the study; 159 of them had not been using OC for at least 12 months prior to their enrolment, while 60 were on regular OC treatment. Results: The median levels of vitamin B-6 and B-12 were significantly lower in OC users than in non-users (24.2 vs. 32.9 nmol/l, p = 0.029; 278 vs. 429 ng/ml, p < 0.001). There were no statistically significant differences in the levels of tHcy (fasting and post-methionine loading) and folate. Conclusions: In our cross-sectional study, OC use was associated with low vitamin B-6 and B-12 levels. Since low vitamin B-6 levels are independently associated with heightened risks for arterial and venous thromboembolism (TE), they could partly account for the increased TE risk of OC users. (C) 2004 Elsevier Ltd. All rights reserved.