Going off birth control may lower levels of vitamin D in women, according to a study published Aug. 4 in the Journal of Clinical Endocrinology and Metabolism. The drop may be dependent upon lifestyle choices, researchers stated in the study.
Researchers investigated the association between the use of hormonal contraception and 25-hydroxy-vitamin D, 25(OH)D. They studied 1,662 black women in Detroit, ages 23-34, taking blood samples and gathering other information that included demographics, dietary and supplement intake, contraceptive use, reproductive and medical history and behaviors.
The blood samples revealed that women who were on either birth control pills, patches or rings containing estrogen had 20% higher vitamin D levels, according to the study. “There was no increase in 25(OH)D among participants who had used estrogen in the past, but were not current users, indicating that results were unlikely to be due to unmeasured confounding by factors related to contraceptive choice,” researchers stated in the study.
The study’s lead author, Quaker Harmon, PhD, a postdoctoral fellow at the U.S. National Institute of Environmental Health Sciences, said in an Endocrine Society press release, “Our findings indicate women may run the risk of developing vitamin D deficiency just when they want to become pregnant. For women who are planning to stop using birth control, it is worth taking steps to ensure that vitamin D levels are adequate while trying to conceive and during pregnancy.”
Results of the study, researchers concluded, “highlight the need for studies that examine possible endogenous estrogen effects on vitamin D.”
Low vitamin D levels are a global concern, according to the Harvard T.H. Chan School of Health website.
“Worldwide, an estimated 1 billion people have inadequate levels of vitamin D in their blood, and deficiencies can be found in all ethnicities and age groups,” the website stated. “Indeed, in industrialized countries, doctors are even seeing the resurgence of rickets, the bone-weakening disease that had been largely eradicated through vitamin D fortification.”
The website further stated that people living north of the line connecting San Francisco to Philadelphia and Athens to Beijing are likely not getting enough vitamin D. Those who do not spend at least 15 minutes per day in the sun are also not getting enough of the vitamin, according to the site.
People with darker skin, those who spend a lot of time indoors, those who cover their skin with clothing or sunscreen, and people who live in the northern part of the U.S. or in Canada are at risk for low vitamin D, according to the Vitamin D Council website. In addition, older people, pregnant women, obese people and breastfed infants who are not given supplements are more likely to be deficient, the site stated.
Meanwhile, an ongoing study funded by the National Institutes of Health is testing whether vitamin D supplements reduce the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of the illnesses.
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