Plasma 25-hydroxyvitamin D and risk of premenstrual syndrome in a prospective cohort study
1 Division of Biostatistics and Epidemiology, Department of Public Health, School of Public Health and Health Sciences, University of Massachusetts, 409 Arnold House, 715 North Pleasant Street, Amherst, MA 01003, USA
2 Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
3 Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
4 Neuroscience Institute, Georgia State University, Atlanta, GA 30302, USA
5 Department of Psychology, University of Massachusetts, Amherst, MA 01003, USA
6 Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA
7 Department of Obstetrics and Gynecology, University of Iowa, Iowa City, IO 52242, USA
8 Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
BMC Women's Health 2014, 14:56 doi:10.1186/1472-6874-14-56Published: 12 April 2014
Moderate to severe premenstrual syndrome (PMS) affects 8–20 percent of premenopausal women. Previous studies suggest that high dietary vitamin D intake may reduce risk. However, vitamin D status is influenced by both dietary vitamin D intake and sunlight exposure and the association of vitamin D status with PMS remains unclear.
We assessed the relation of plasma 25-hydroxyvitamin D (25OHD), total calcium and parathyroid hormone levels with risk of PMS and specific menstrual symptoms in a case–control study nested within the prospective Nurses’ Health Study II. Cases were 401 women free from PMS at baseline who developed PMS during follow-up (1991–2005). Controls were women not experiencing PMS (1991–2005), matched 1:1 with cases on age and other factors. Timed luteal phase blood samples were collected between 1996 and 1999 from cases and controls. We used conditional logistic regression to model the relation of 25OHD levels with risk of PMS and individual menstrual symptoms.
In analyses of all cases and controls, 25OHD levels were not associated with risk of PMS. However, results differed when the timing of blood collection vs. PMS diagnosis was considered. Among cases who had already been diagnosed with PMS at the time of blood collection (n = 279), 25OHD levels were positively associated with PMS, with each 10 nmol/L change in 25OHD associated with a 13% higher risk. Among cases who developed PMS after blood collection (n = 123), 25OHD levels were unrelated to risk of PMS overall, but inversely related to risk of specific menstrual symptoms. For example, each 10 nmol/L increase was associated with a significant 21% lower risk of breast tenderness (P = 0.02). Total calcium or parathyroid hormone levels were unrelated to PMS.
25OHD levels were not associated with overall risk of PMS. The positive association observed among women already experiencing PMS at the time of 25OHD measurement is likely due to confounding by indication related to use of dietary supplements to treat menstrual symptoms. Results from prospective analyses, which were less likely influenced by this bias, suggest that higher 25OHD levels may be inversely related to the development of specific menstrual symptoms.