Blood levels of homocysteine, folate, vitamin B6 and B12 in women using oral contraceptives compared to non-users

Thromb Res. 2003;112(1-2):37-41. doi: 10.1016/j.thromres.2003.11.007.


Background and objectives: To compare the levels of total homocysteine (tHcy), folate, vitamin B6 and B12, 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 enrollment, while 60 were on regular OC treatment.

Results: The median levels of vitamin B6 and B12 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 B6 and B12 levels. Since low vitamin B6 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.

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Contraceptives, Oral / adverse effects*
  • Female
  • Folic Acid / blood*
  • Homocysteine / blood*
  • Humans
  • Middle Aged
  • Risk Assessment / methods*
  • Thromboembolism / blood*
  • Thromboembolism / chemically induced*
  • Vitamin B 12 / blood*
  • Vitamin B 6 / blood*


  • Contraceptives, Oral
  • Homocysteine
  • Vitamin B 6
  • Folic Acid
  • Vitamin B 12