Vitamin D may reduce menstrual cramp pain
In this meta-analysis of randomized controlled trials, supplementation with vitamin D reduced pain due to dysmenorrhea (menstrual cramps), but not dysmenorrhea pain that was related to endometriosis.
Vitamin C and E for endometriosis pain
Supplements for menstrual cramps and pelvic pain in women with endometriosis
Can dark chocolate reduce pain due to menstrual cramps?
Taking vitamin D may reduce menstrual pain