The Effects of Evening-Primrose Oil on Menopausal Symptoms: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract

Background: Evening primrose oil (EPO) has been a treatment option for reducing menopausal symptoms, but evidence for its use is inadequate. Objective: The study aimed to determine the effectiveness of EPO in treating menopausal symptoms among peri and postmenopausal women. Study design: This is a systematic review with meta-analyses of randomised clinical trials (RCTs). Methods: We searched CENTRAL, Medline, Embase and trial registries for relevant RCTs. The methodology and reporting were carried out grounded on references from the Cochrane collaboration and the preferred reporting items for systematic reviews and meta-analyses statement. Review Manager version 5.3.5 was used to perform all the statistical analyses. Results: Five RCTs, recruiting a total of 402 peri and postmenopausal women were identified. EPO did not reduce the frequency of daily vasomotor symptoms (MD 0.01 episodes, 95% CI -0.54 to 0.57, P=0.960), frequency of daytime hot flash episodes (MD -0.51 episodes, 95% CI -2.05 to 1.03, P=0.510), frequency of night sweat episodes (MD 0.33 episodes, 95% CI -0.48 to 1.13, P=0.430) and severity of vasomotor symptoms (SMD -0.45, 95% CI -1.56 to 0.66, P=0.420) in comparison to control. EPO was associated with a minimal reduction in the severity of overall menopausal symptoms in comparison to control (SMD -1.18; 95% CI-2.18 to -0.18, P=0.02). There were insufficient data to pool results for musculoskeletal symptoms, mood, sexuality, sleeping disorders and quality of life. Conclusion: EPO may reduce the severity of overall menopausal symptoms but is not effective to reduce the frequency and severity of vasomotor symptoms. The evidence quality ranged from very low to moderate. Further research is needed to enhance related evidence.