The Effect of Flaxseed Supplementation on Sex Hormone Profile in Adults: A Meta-Analysis

Flaxseed has been suggested as a viable solution to improve sex hormones. However, conflicting and uncertain evidence regarding its impact on sex hormone profiles exists. This meta-analysis assesses the effects of flaxseed on sex hormone profiles. PubMed, Scopus, Embase, and the Web of Science were searched for relevant articles in August 2021. The Cochrane Collaboration tool was used for the quality assessment, and the evidence's trustworthiness was assessed using the Grading of Assessment, Development, and Evaluation of Recommendations (GRADE). A total of ten articles revealed that flaxseed might not have a significant effect on follicle-stimulating hormone (FSH) ((WMD: 0.84; 95% CI: -5.53, 7.00, p =0.791; I2= 88.6%, p<0.001, level of confidence: low), sex hormone-binding globulin (SHBG) ((WMD: 2.17; 95% CI: -1.19, 5.54, p =0.206; I2= 66.3%, p=0.011, level of confidence: low), total testosterone (TT) (WMD: -0.00; 95% CI: -0.07, 0.07, p=0.968; I2= 41.3%, p =0.146, level of confidence: low), free androgen index (FAI) (WMD: -0.13; 95% CI: -0.68, 0.42; p=0.645; I2= 85.4%, p<0.001, level of confidence: low) and dehydroepiandrosterone sulfate (DHEAS) (WMD: 0.62; 95% CI: -3.35, 4.59, p=0.761; I2=63.6%, p =0.064, level of confidence: very low). It is demonstrated that flaxseed might not affect sex hormones in adults. Flaxseed supplementation had no significant effect on sex hormones in adults. Nevertheless, due to the limited included trials, this topic is still open and needs further studies in future RCTs.