Calcium and vitamin D intake and risk of incident premenstrual syndrome

Background: Premenstrual syndrome (PMS) is one of the most common disorders of premenopausal women. Studies suggest that blood calcium and vitamin D levels are lower in women with PMS and that calcium supplementation may reduce symptom severity, but it is unknown whether these nutrients may prevent the initial development of PMS. Methods: We conducted a case-control study nested within the prospective Nurses' Health Study 11 cohort. Participants were a subset of women aged 27 to 44 years and free from PMS at baseline in 1991, including 1057 women who developed PMS over 10 years of follow-up and 1968 women reporting no diagnosis of PMS and no or minimal menstrual symptoms. Intake of calcium and vitamin D was measured in 1991, 1995, and 1999 by a food frequency questionnaire. Results: After adjustment for age, parity, smoking status, and other risk factors, women in the highest quintile of total vitamin D intake (median, 706 IU/d) had a relative risk of 0.59 (95% confidence interval, 0.40-0.86) compared with those in the lowest quintile (median, 112 IU/d) (P=.01 for trend). The intake of calcium from food sources was also inversely related to PMS compared with women with a low intake (median, 529 mg/d), participants with the highest intake (median, 1283 mg/d) had a relative risk of 0.70 (95% confidence interval, 0.50-0.97) (P=.02 for trend). The intake of skim or low-fat milk was also associated with a lower risk (P <.001). Conclusions: A high intake of calcium and vitamin D may reduce the risk of PMS. Large-scale clinical trials addressing this issue are warranted. Given that calcium and vitamin D may also reduce the risk of osteoporosis and some cancers, clinicians may consider recommending these nutrients even for younger women.