ABSTRACT
BACKGROUND AND OBJECTIVE: Several trials have evaluated the effects of folate supplementation on obesity indices. However, their results were inconsistent. Therefore, the current meta-analysis was conducted to summarize data from available randomized clinical trials (RCTs) about the impact of folate supplementation on weight and body mass index (BMI). METHOD: Medline/PubMed, Scopus, Embase, and ISI web of science were searched to identify relevant articles up to December 2020. The effect sizes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI) using the random-effects model. RESULTS: Pooled data from nine studies showed that folic acid supplementation did not change body weight (WMD: -0.16 kg, 95%CI: -0.47 to 0.16, P = 0.32) and BMI (WMD: -0.23 kg/m2, 95%CI: -0.49 to 0.03, P = 0.31), but there was significant heterogeneity between the included studies for BMI (I2 = 90.1%, P < 0.001). Moreover, subgroup analyses in level of homocysteine and health status indicated significant effect of folic acid supplementation on BMI in those with homocysteine level ≥15 µmol/L (WMD: -0.17 kg/cm2, -0.33 to -0.01, p = 0.03) and in women with polycystic ovary syndrome (PCOS) (WMD: - 0.30kg/cm2, -0.54 to -0.06, p = 0.01). CONCLUSION: Our outcomes demonstrated that folic acid improves BMI in those with homocysteine levels ≥15 µmol/L and women with PCOS.