Vitamin D Levels May Drop After Discontinuing Contraceptives

Women who stop using birth control pills or other contraceptives containing estrogen are at risk of having their vitamin D levels drop, according to a recent study.

Research suggests that exogenous estrogen may be associated with higher levels of vitamin D, but it is unclear whether lifestyle choices such as amount of sun exposure and diet could be affecting the level of vitamin D in women taking the hormone.
________________________________________________________________________________________________________________________________________________________________________

RELATED CONTENT
Vitamin D Linked to Improved Cardiac Function in Heart Failure Patients
Is Vitamin D Beneficial to Knee Osteoarthritis Patients?
________________________________________________________________________________________________________________________________________________________________________

To conduct their analysis, the researchers collected data from 1662 African American women aged 23 to 34 years living in the Detroit, Michigan, area and participating in the Study of Environmental, Lifestyle, and Fibroids (SELF) study.

During the SELF study, participants completed questionnaires about their contraception use, amount of time spent outside, and intake of vitamin D supplements. They also provided blood samples at baseline in order for researchers to measure 25-hydroxyvitamin D levels.

After adjusting for amount of sun exposure, the researchers found that using contraceptive pills, patches, or rings containing estrogen was associated with a 20% higher level of 25-hydroxyvitamin D levels.

No increases were observed in women who had used estrogen in the past but were not currently using it. This indicates that the results were unlikely to be due to unmeasured confounding factors.

“The increase in [25-hydroxyvitamin D] with use of estrogen-containing contraceptives raise[s] mechanistic questions regarding the biological pathways involved, and highlights the need for studies that examine possible endogenous estrogen effects on vitamin D,” the researchers concluded.

—Amanda Balbi

Reference:

Harmon QE, Umbach DM, Baird DD. Use of estrogen-containing contraception is associated with increased concentrations of 25-hydroxy vitamin D [published online August 4, 2016]. J Clin Endocrinol Metab. http://dx.doi.org/10.1210/jc.2016-1658#sthash.dYG4FG38.dpuf.