Effects of n-3 polyunsaturated fatty acid on metabolic status in women with polycystic ovary syndrome: a meta-analysis of randomized controlled trials

This meta-analysis was conducted to summarize the effects of n-3 polyunsaturated fatty acid (n-3 PUFA) on metabolic status including insulin metabolism and lipid metabolism in women with polycystic ovary syndrome (PCOS) by randomized controlled trials (RCTs). Four mainstream databases including PubMed, Cochrane Library, Embase and Web of Science were searched from their inception to October 2021. The registration number of this study was CRD42021285233. The quality assessment was performed referring the Cochrane Risk of Bias Tool. Mean differences (MD) and 95% confidence intervals (CIs) were generated for continuous variables by meta-analysis. Subgroup analyses were performed based on study duration (≤ 8 weeks or > 8 weeks), the source of n-3 PUFA (marine derived or plant origins) and dosage of n-3 PUFA (≤ 1000 mg/d or > 1000 mg/d). Eventually, 11 RCTs reporting 816 patients were enrolled. Compared with control group, n-3 PUFA treatment decreased waist circumference (MD = -2.76, 95% CI: -3.82 to -1.69; p < 0.00001), fasting plasma glucose (MD = -3.91, 95% CI: -5.69 to -2.13; p < 0.0001), fasting insulin (MD = -2.45, 95% CI: -3.19 to -1.71; p < 0.00001), homeostatic model assessment of insulin resistance (MD = -0.45, 95% CI: -0.80 to -0.11; p = 0.01), triglyceride (MD = -9.33, 95% CI: -10.56 to -8.10; p < 0.00001), total cholesterol (MD = -12.32, 95% CI: -19.15 to -5.50; p = 0.0004), low-density lipoprotein cholesterol (MD = -10.53, 95% CI: -19.31 to -1.75; p = 0.02), and increase quantitative insulin sensitivity check index (MD = 0.01, 95% CI: 0.01 to 0.02; p < 0.00001), Adiponectin (MD = 1.46, 95% CI: 1.12 to 1.80; p < 0.00001) in PCOS patients. However, n-3 PUFA failed to change body weight, body mass index, high-density lipoprotein cholesterol, very low-density lipoprotein cholesterol and hs-CRP in the overall analysis. Further subgroup analyses showed that supplements of n-3 PUFA for more than 8 weeks is more conducive to improve the metabolic status in insulin resistance and lipid profiles. The meta-analysis demonstrates that n-3 PUFA may be an effective intervention for alleviating metabolic status in PCOS. Hence, we recommend PCOS patients replenish n-3 PUFA with duration > 8 weeks regardless of the source and the dosage to retard the pathogenesis of PCOS related metabolic diseases.