It is known that exogenous estrogen may improve vitamin D status. However, the cause is still unclear because women who use hormones may make lifestyle choices that differentially affect vitamin D status.
In a recent study, researchers find that women who stop using birth control methods that contain estrogen can have reduced vitamin D levels. The finding is published in Journal of Clinical Endocrinology & Metabolism.
Researchers from National Institute of Environmental Health Sciences conducted the study. They investigated the association between use of hormonal contraception and 25-hydroxy-vitamin D.
A total of 1,662 American women, community volunteers, 23–34 years old, living in the Detroit, Michigan, area were included.
At the enrollment clinic visit into a study during 2010-2012, each woman provided a blood sample, and answered questionnaires on demographics, dietary and supplement intake, contraceptive use, reproductive and medical history.
Researchers find that vitamin D concentrations were low (70% <20 ng/ml) in these women. Current use of an estrogen-containing contraceptive was associated with a 20% increase in vitamin D.
There was no increase in vitamin D among women who had used estrogen in the past, but were not current users. This indicated that results were unlikely to be due to unmeasured confounding by factors related to contraceptive choice.
Researchers suggest that the increase in vitamin D with use of estrogen-containing contraceptives raises mechanistic questions regarding the biological pathways involved. In the future, studies need to examine possible endogenous estrogen effects on vitamin D.
Citation: Harmon QE, et al. (2016). Use of Estrogen-Containing Contraception Is Associated With Increased Concentrations of 25-Hydroxy Vitamin D. The Journal of Clinical Endocrinology & Metabolism, published online. DOI: 10.1210/jc.2016-1658.
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