Women may find some relief from menstrual cramps by taking vitamin E a few days a month, new research suggests.

The study, of teenage girls in Iran, found that those who took vitamin E starting two days before their periods suffered far less cramping than their peers who used only standard pain medication.

After four months, the girls who took vitamin E had cramps for less than two hours, on average, during their periods. That compared with 17 hours for those who did not take the vitamin.

Dr. Saeideh Ziaei and her colleagues at Tarbiat Modarres University in Tehran report the findings in the British Journal of Obstetrics and Gynecology.

Common menstrual cramps, or primary dysmenorrhea, are thought to result from the release of hormone-like substances called prostaglandins. Prostaglandins cause the uterus to contract in order to expel the uterine lining, resulting in menstrual blood flow. Vitamin E, by acting on two enzymes in the body, can inhibit the formation of prostaglandins -- and, potentially, menstrual cramps, according to Ziaei and her colleagues.

To investigate, the researchers randomly assigned 278 girls, 15 to 17 years old, with primary dysmenorrhea to take either vitamin E or an inactive placebo pill. Girls in the vitamin E group took 200 milligrams (mg) of the vitamin twice a day, starting two days before they expected their periods and continuing through the third day of menstruation.>

Both groups were allowed to take ibuprofen if they needed to.

After four months, girls in the vitamin E group showed a sharp reduction in the number of hours they suffered cramps each month. Few -- 4 percent -- reported using ibuprofen, compared with 89 percent of girls in the placebo group.

Girls in both groups tended to say their periods got lighter during the study period, but the change was greater in the vitamin group, according to Ziaei's team.

The dose of vitamin E used in the study -- 200 mg twice a day -- is significantly higher than the recommended daily intake of 20 mg, but still well within the range that experts consider unlikely to cause adverse effects. U.S. health officials set the "upper tolerable intake level" for vitamin E at 1,000 mg per day.

"The use of vitamin E for dysmenorrhea in adolescent women is attractive," Ziaei's team writes, "because of the marked effect we have demonstrated, coupled with the absence of significant side effects from vitamin E at therapeutic doses."

SOURCE: British Journal of Gynecology, April 2005.