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clip_image002Something as simple as vitamin D can help some with menstrual cramps. A recent study included 40 women ages 18-40 who had menstrual cramps for at least four consecutive months within the previous 6 months and who had a blood level of vitamin D < 45 ng/mL. None of the women were taking calcium, vitamin D, birth control pills, IUD or other medications within the previous 6 months as well. The study allowed them to take nonsteroidal anti-inflammatory drugs (NSAIDS) but they were to record their use of these medications.

Women were randomized to receive a single high dose of vitamin D of 300,000 I.U. or placebo 5 days before the anticipated onset of their next menstrual period. The primary measured outcome was the intensity of the menstrual pain and the secondary outcome was the use of NSAIDS. After two months/two menstrual periods, the pain scores decreased 41% in the vitamin D group and there was no difference in the placebo group. The greatest reduction in pain was seen in the women in the vitamin D group who had the most severe pain at baseline. In addition, none of the women in the vitamin D group needed NSAIDS to manage their pain at 1 and 2 months while 40% of the women in the placebo group used an NSAID at least one time.

Commentary: Acute menstrual pain, called dysmenorrhea, affects almost half of menstruating women. The menstrual pain is thought to be triggered by excessive uterine production of prostaglandins, synthesized from omega-6 fatty acids before menses that control vasoconstriction and uterine contractions. It is thought that vitamin D may act as an anti-inflammatory and may regulate prostaglandin pathways. What we don’t know is how many menstrual cycles the effect of that one dose of vitamin D might offer these results. We also do not know if this dosing of vitamin D would help women who had higher blood levels of vitamin D to begin with. It is interesting that the study participants had levels below 45 ng/mL, which is not deficient or insufficient. Most clinicians use the cut-off that if below 20ng/mL you are deficient and below 30 ng/mL you are insufficient.


Antonino L, Antonino C, Salvatore B. Improvement of Primary Dysmenorrhea Caused by a Single Oral Dose of Vitamin D: Results of a Randomized, Double-blind, Placebo-Controlled Study Arch Intern Med. 2012;172(4):366-367.