Effects of Calcium-Vitamin D and Calcium-Alone on Pain Intensity and Menstrual Blood Loss in Women with Primary Dysmenorrhea: A Randomized Controlled Trial

Objective: There is limited evidence on effectiveness of calcium and vitamin D on dysmenorrhea. The authors aimed to determine the effect of combined calcium-vitamin D and calcium-alone on pain intensity and menstrual blood loss in women with primary dysmenorrhea.

Design: A randomized double-blind trial.

Setting: Dormitories of Tabriz University of Medical Sciences.

Subjects: 85 students with moderate or severe primary dysmenorrhea.

Methods: Participants were randomized into three groups: receiving one tablet/day of 1000 mg calcium + 5000 IU vitamin D3, calcium-alone 1000 mg, or matched placebo, from 15th cycle day until menstrual pain disappearance in the following cycle, for three cycles. Pain intensity and menstrual blood loss were assessed one cycle before, three cycles under, and one cycle following intervention using 10-cm visual analog scale and pictorial blood loss assessment chart, respectively. The groups were compared using repeated measures ANOVA.

Results: Time after intervention and interaction of time with group had no significant effects on the outcomes. Compared to the placebo group, mean pain intensity was lower in the both calcium-vitamin D (adjusted difference -0.7, 95% confidence interval -1.6 to 0.3) and calcium-alone (-1.6, -2.6 to -0.6) groups, but the difference was statistically significant only in the calcium-alone group. Menstrual blood loss was not significantly different in the either calcium-vitamin D (-4.7, -21.9 to 12.4) or calcium-alone (-0.4, -17.4 to 16.4) groups compared to placebo.

Conclusions: Intake of the calcium-alone was effective in reducing menstrual pain intensity. The results could not indicate significant effects of calcium-vitamin D on the pain or any of the interventions on menstrual blood loss.

Clinical Trial Registration: This study was approved by the Ethics committee of Tabriz University of Medical Sciences (code 92145) and registered at the Iranian Registry of Clinical Trials with IRCT201402043706N21.