Vitamin D’s primary role is to maintain the correct calcium and phosphorous levels in the blood.
It also helps the body absorb calcium, an essential component of bones.
Foods including fish and eggs are high in vitamin D, however, around 90 percent of vitamin D is produced in the skin through a chemical reaction after exposure to sunlight.
Vitamin D deficiency can lead to rickets and osteomalacia (softening of the bones).
Because vitamin D is vital in the formation of bones, it is particularly important during pregnancy.
Dr. Quaker E. Harmon, of the National Institutes of Health’s National Institute of Environmental Health Sciences in Research Triangle Park, NC, decided to investigate any changes in vitamin D levels associated with taking oral contraceptives.
The researchers carried out a cross-sectional analysis of data from the Study of Environment, Lifestyle, and Fibroids (SELF), an investigation of reproductive health. The project used almost 1,700 African-American women living in and around Detroit, MI, aged 23-34.
The study asked women about their contraceptive use and included questions about the amount of time they spent outside and any vitamin D supplements they took.
In total, 1,662 women gave blood samples to ascertain levels of the most common circulating form of vitamin D, called 25-hydroxy vitamin D.