Improvement of primary dysmenorrhea caused by a single oral dose of vitamin D: results of a randomized, double-blind, placebo-controlled study.

P rimary dysmenorrhea is a common disorder characterized by painful uterine cramping, just before or during menstruation, in the absence of any pelvic pathologic conditions. It is frequently accompanied by other symptoms such as nausea, vomiting, diarrhea, asthenia, and insomnia. Primary dysmenorrhea affects almost half of menstruating women, often resulting in school and work absenteeism with major educational and economic consequences. An excessive uterine production of prostaglandins (PGs) is the pathogenetic trigger of dysmenorrhea. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the currently accepted drugs for the management of this disorder. Because the vitamin D receptor is widespread and the mitochondria l cytochrome P450 enzyme 25hydroxyvitamin D3 (25[OH]D)-1 -hydroxylase (1 OHase), which catalyzes the synthesis of 1 ,25dihydroxyvitamin D3 (1,25[OH]2D) from its precursor 25(OH)D, is expressed in the human uterus and in immune system cells, and because vitamin D reduces the synthesis of PGs, a beneficial effect of vitamin D in the uterus pathophysiology is possible. The aim of this prospective intervention study was to evaluate the effect of a single-loading oral dose of cholecalciferol (300 000 IU) on primary dysmenorrhea.