Humans have an innate relationship with the sun. Ancient civilizations worshipped it.1 Our 365-day calendar was created around it.2 And when bare skin is exposed to its ultra violet rays, the human body produces an essential nutrient—vitamin D.3
Decades of studies have shown how vitamin D receptors are found in almost every cell of the body, influencing different levels of tissue and organ function.4 And now, emerging research is pinpointing how vitamin D, and more specifically sunlight exposure, may offer protection from chronic conditions like uterine fibroids.
Vitamin D, Sun Exposure, and Fibroids
A recent study published in Epidemiology5 evaluated 620 African American women and 416 Caucasian women, ages 35-49, in the National Institute of Environmental Health Sciences Uterine Fibroid Study.
Researchers determined participant vitamin D status by analyzing 25-hydroxyvitamin D levels (the precursor to active vitamin D) from collected blood samples. Ultrasound examinations were performed to establish the presence or absence of uterine fibroids. Additionally, data from a survey on self-reported sun exposure was gathered. Utilizing each piece of the puzzle, the authors then investigated whether vitamin D levels were associated with fibroid status in women.
Results of the study showed that women who had sufficient serum 25-hydroxyvitamin D levels, deemed as 20ng/mL or higher, had a 32% reduced risk of having fibroids when compared to those who had lower levels. Additionally, those who reported at least one hour per day of sun exposure also had a reduced risk.
Further investigation is needed, but these findings are consistent with results from previous in vitro studies and animal studies where treatment with active vitamin D metabolites slowed the growth of cultured uterine fibroid tissue. The authors concluded that “the consistency of [the current] findings provide evidence that sufficient vitamin D is associated with a reduced risk of uterine fibroids.”
How Much Sun Do I Need?
Exact recommendations are not easy to make. Individuals make vitamin D at different rates due to factors like skin pigment, age, season, and location in proximity to the equator. The Vitamin D Council suggests, “The best recommendation is to get half the sun exposure it takes for your skin to turn pink.”6
If you aren’t able to get enough sun or if you’re concerned about skin damage, a vitamin D supplement is another viable option. There are vitamin D food sources like fatty fish and egg yolks, but these foods probably won’t provide enough vitamin D. “Most foods that contain vitamin D only have small amounts,” the Vitamin D Council clarifies. “So it’s almost impossible to get what your body needs just from food.”6
The recommended daily allowance of vitamin D for adults 19-70 years of age is 600 IU. After 70, this amount increases to 800 IU.7 Although vitamin D shows promise and may naturally reduce the risk of fibroids, it’s still important to first discuss supplementation with your physician.
ABOUT THE AUTHOR Alicia Armeli has a Master of Science in Nutrition and Whole Foods Dietetics (MSN/DPD) and is a registered dietitian nutritionist, a certified dietitian, and a holistic life coach. In addition to writing, she enjoys singing, traveling abroad and volunteering with her local animal shelter.
- Encyclopædia Britannica. (2015). Aton, Egyptian God. Retrieved June 6, 2015, from http://www.britannica.com/EBchecked/topic/41851/Aton
- Time and Date. (2015). The Gregorian Calendar. Retrieved June 5, 2015, from http://www.timeanddate.com/calendar/gregorian-calendar.html
- Deluca, H. F. (2014). History of the discovery of vitamin D and its active metabolites. Bone Key Reports, 3(479). doi: 10.1038/bonekey.2013.213
- Pludowski, P., Holick, M. F., Pilz, S., Wagner, C. L., Hollis, B. W., Grant, W. B., Shoenfeld, Y., Lerchbaum, E., Llewellyn, D. J., Kienreich, K., & Soni, M. (2013). Vitamin D effects on musculoskeletal health, immunity, autoimmunity, cardiovascular disease, cancer, fertility, pregnancy, dementia and mortality—A review of recent evidence. Autoimmunity Reviews, http://dx.doi.org/10.1016/j.autrev.2013.02.004
- Baird, D. D., Hill, M. C., Schectman, J. M., & Hollis, B. W. (2013). Vitamin d and the risk of uterine fibroids. Epidemiology, 24(3):447-53. doi:10.1097/EDE.0b013e31828acca0
- Vitamin D Council. (2015). How do I get the vitamin D my body needs? Retrieved June 8, 2015, from http://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get-the-vitamin-d-my-body-needs/#
- National Institutes of Health. (2014). Vitamin D, Fact Sheet For Health Professionals. Retrieved June 8, 2015, from http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/