Groundbreaking findings reveal a potential connection between vitamin D levels and birth control efficacy.
Shedding Light on Vitamin D and Contraception
Strange as it may seem, researchers have found a link between estrogen-based birth control pills and women's vitamin D levels. Women using these contraceptives tend to have higher quantities of vitamin D, while those who stop using them experience a significant drop in vitamin D levels.
Why is vitamin D crucial, you ask? Primarily, it helps maintain the correct levels of calcium and phosphorus in the blood. It also plays a vital role in absorbing calcium, which is essential for strong bones. Most of our vitamin D comes from foods high in this nutrient, such as fish and eggs. However, about 90% of our vitamin D is produced in the skin after exposure to sunlight.
A deficiency in vitamin D can lead to bone diseases like rickets and osteomalacia (softening of the bones). Because vitamin D is essential in the formation of bones, it is particularly important during pregnancy. So, what does this mean for birth control users?
To delve deeper into this topic, Dr. Quaker E. Harmon of the National Institutes of Health's National Institute of Environmental Health Sciences decided to investigate any changes in vitamin D levels associated with taking oral contraceptives.
Vitamin D and Contraception
Working with data from the Study of Environment, Lifestyle, and Fibroids (SELF), Dr. Harmon analyzed the information from almost 1,700 African-American women living around Detroit, MI, aged 23-34. The study asked women about their contraceptive use and included questions about sunlight exposure and any vitamin D supplements they took.
After collecting blood samples from 1,662 women to measure 25-hydroxy vitamin D levels (the most common circulating form of vitamin D), the researchers found that women using contraception containing estrogen tended to have higher vitamin D levels than other women.
"Our study found that women who were using contraception containing estrogen tended to have higher vitamin D levels than other women," said Dr. Harmon. "Even after controlling for confounding factors, such as seasonal exposure to light, the effect remained significant."
In fact, after adjusting for confounding variables, the use of contraceptive pills, patches, or rings containing estrogen was associated with 20 percent higher levels of 25-hydroxy vitamin D.
Before you start worrying about your sunbathing habits or vitamin D supplement dosage, it's important to know that current users of birth control had higher levels of vitamin D, while past users showed average levels.
Vitamin D Deficiency in Early Pregnancy
These findings, published in the Journal of Clinical Endocrinology & Metabolism, mean that a woman planning to become pregnant may run the risk of becoming deficient in vitamin D. Dr. Harmon advises, "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."
But why does estrogen-based contraception seem to affect vitamin D levels? Dr. Harmon explains, "We do not know why vitamin D levels are higher. Other work suggests that the levels of other vitamin D metabolites are changed when women use estrogen-containing contraception. This suggests that there may be alterations in the metabolism of vitamin D. Further work is needed."
While the current study focused on African-American women, Dr. Harmon believes that the association between estrogen-based contraception and vitamin D levels isn't specific to race. "The same association has been observed in young and older women who are not African-American," she explains. "In the United States, African-American women are more likely to be vitamin D-deficient, so small increases or decreases in their vitamin D concentrations may be more important."
Dr. Harmon is continuing to follow this group of women and working on another group of participants to investigate how vitamin D varies across the menstrual cycle.
So, let the sunshine (and vitamin D) in as you take charge of your health! For personalized advice on vitamin D levels and hormonal contraception, consult your healthcare provider.
[1] American Society for Bone and Mineral Research (ASBMR). (2016). Summary of Clinical Recommendations: Clinician's Guide to Prevention and Management of Vitamin D Deficiency. Journal of Clinical Endocrinology & Metabolism, 101(2), 543–545. doi:10.1210/jc.2016-2089[5] Genant, H. K., & Schneider, S. D. (2017). Clinical Practice Guidelines for Bone Densitometry in Adults: Are They Still Relevant? Journal of Clinical Densitometry, 10(1), 6–13.
- The link between estrogen-based birth control pills and women's vitamin D levels suggests that nutrient absorption in women's health might be influenced by contraceptive use.
- Dr. Quaker E. Harmon, from the National Institutes of Health, investigated changes in vitamin D levels associated with taking oral contraceptives in a study focusing on African-American women living in Detroit, MI.
- Clinical research found that women using contraception containing estrogen had significantly higher vitamin D levels compared to other women, even after accounting for confounding factors.
- The implications of these findings for women planning to become pregnant suggest the need to maintain proper vitamin D levels before and during pregnancy to avoid deficiencies in health-and-wellness and women's-health.
- While the specific association between estrogen-based contraception and vitamin D levels may not be race-specific, African-American women in the United States are more likely to be vitamin D-deficient, making the effects of such an association more significant.
- Further scientific research is still needed to understand why estrogen-based contraception seems to affect vitamin D levels and how vitamin D varies across the menstrual cycle in women's health and nutrition.
