Vitamin D's potential role in hormonal contraceptive methods unearthed
Vitamin D: Rollercoaster Ride for Birth Control Users
Women on estrogen-based birth control pills might have higher vitamin D levels, while those who stop taking these contraceptives could experience a significant drop. Here's the lowdown on this intriguing vitamin, and how it interacts with our favorite contraceptive choices.
Vitamin D: The Skeletal Sherpa
Vitamin D's primary job is balancing calcium and phosphorous levels in your bloodstream. It also aids in calcium absorption, a crucial component of your bones. While you'll find plenty of this vital nutrient in fish and eggs, around 90% of our vitamin D is produced in our skin after exposure to sunlight.
Sun, Sea, and D
Deficiency in vitamin D can lead to rickets and osteomalacia, or softening of the bones. Because vitamin D plays a crucial role in forming bones, it's particularly vital during pregnancy.
The Contraceptive Connection
Intrigued by the relationship between vitamin D and contraception, Dr. Quaker E. Harmon from the National Institutes of Health's National Institute of Environmental Health Sciences decided to investigate.
The researchers examined data from the Study of Environment, Lifestyle, and Fibroids (SELF), an investigation of reproductive health. The study included almost 1,700 African-American women living in and around Detroit, MI, aged 23-34. The research team asked women about their contraceptive use, time spent outside, and the use of any vitamin D supplements.
In total, 1,662 women gave blood samples to ascertain the levels of the most common circulating form of vitamin D, called 25-hydroxy vitamin D. During pregnancy, women produce increased levels of the active form of vitamin D to support the growth of the fetal skeleton. Due to this, pregnant women have a higher risk of vitamin D deficiency and bone problems.
Estrogen-Fueled Vitamin D
The researchers found that women using contraception containing estrogen tended to have higher vitamin D levels than other women. Even after controlling for confounding factors, such as seasonal light exposure, the effect remained significant.
"Our findings suggest that contraceptives containing estrogen tend to boost vitamin D levels, and those levels are likely to fall when women cease using contraception," said Dr. Harmon.
After adjusting for confounding variables, the use of contraceptive pills, patches, or rings containing estrogen was associated with 20% higher levels of 25-hydroxy vitamin D.
As women stopped using birth control, their vitamin D levels dropped, too.
Vitamin D in Early Pregnancy
A woman starting to try for a baby might face vitamin D deficiency. Dr. Harmon advises, "For women who are planning to stop using birth control, it's worth taking steps to ensure that vitamin D levels are adequate while trying to conceive and during pregnancy."
Why the Estrogen-Vitamin D Connection?
Estrogen's influence on vitamin D levels could be due to its effects on vitamin D–binding protein (DBP) in the blood. By increasing DBP, it raises the total circulating levels of vitamin D metabolites. However, this may decrease the amount of free (bioavailable) vitamin D available for tissue use. Additionally, estrogen impacts liver enzymes involved in vitamin D metabolism, possibly modifying the conversion of vitamin D to its active forms.
Race, Vitamin D, and Contraception
The same association has been observed in women of different races. In the United States, African-American women have a higher likelihood of vitamin D deficiency, so small changes could have more significant effects on their vitamin D levels.
The Future of Vitamin D Research
Dr. Harmon continues to investigate the relationship between vitamin D and contraception, and is working on another group of participants to understand how vitamin D varies across the menstrual cycle.
[1] Source: PubMed Central (PMC)[5] Source: NCBI – National Center for Biotechnology Information
- Higher vitamin D levels may be observed in women using estrogen-based birth control pills, while those who discontinue usage could experience a significant drop, suggesting a connection between the two.
- Vitamin D plays a vital role in maintaining calcium and phosphorous levels in the bloodstream, aiding in calcium absorption, which is essential for bone health, especially during pregnancy.
- Intrigued by this connection, researchers from the National Institutes of Health's National Institute of Environmental Health Sciences investigated the relationship between vitamin D and contraception in a study of reproductive health.
- The study, which included over 1,600 African-American women, found that women using contraception containing estrogen tended to have higher vitamin D levels compared to others, even after controlling for factors like seasonal light exposure.
- The estrogen-vitamin D connection could be due to estrogen's effects on vitamin D–binding protein (DBP) and liver enzymes involved in vitamin D metabolism.
- In the United States, African-American women have a higher likelihood of vitamin D deficiency, making small changes in their vitamin D levels more impactful, particularly when considering their reproductive health and women's health in general.
