Objective: To determine whether essential fatty acids are effective in the treatment of premenstrual syndrome (PMS).
Methods: In a randomized, double-blind, crossover trial, we studied 27 women diagnosed with PMS over ten menstrual cycles and 22 symptom-free controls over one cycle. The first cycle was used for diagnostic assessment. For the women with PMS, placebos were administered during the second cycle. This was followed by randomization to four cycles of active treatment with essential fatty acids and four cycles of placebo, with a crossover after completion of the fourth cycle. Assessment of symptoms and diagnosis of PMS were based on daily self-ratings made by the women throughout the study.
Results: Treatment with essential fatty acids did not reduce premenstrual symptoms or symptom cyclicity. However, time had a significant effect on a number of symptoms, indicating either a placebo effect or an effect from participation in the study. Women with PMS had a significantly higher frequency of dysmenorrhea and familial PMS than did the symptom-free controls.
Conclusion: Treatment with essential fatty acids is ineffective therapy for PMS. The improvement we observed over time can be ascribed to either a placebo effect or participation in the study.