This systematic review assessing the effects of probiotics supplementation in overweight or obese postmenopausal women included 5 randomized trials. The meta-analysis of the trials evaluating the probiotics vs. control suggest there were obvious decreases in insulin reduction (MD = -4.20 IU/L) and HOMA-IR reduction (MD = -1.25). Other evaluated parameters, body adiposity, lipid profile, inflammatory biomarkers and glucose have shown improvements after probiotics consumption, but these improvements were not significant. Probiotics supplementary also may influence iron metabolism in obese postmenopausal female patients, it need more trails to verify.
However, to the best of our knowledge, this is the first review including only overweight or obese postmenopausal women to assess the effects of probiotics. Compare this systematic review with other studies aimed at overweight or obese adults, we can find there have some consistence with previous systematic reviews. This review showed administration of probiotics can make a reduction of BMI (MD = -0.34 kg/m2) but the reduction is not significant (p = 0.07). In previous review aimed at overweight or obese adults, including male and female, Pontes et al. [31] presented a significant decrease which was 0.24 kg/m2, Wang et al.[32] shown a significant reduction of 0.3 kg/m2, Borgeraas et al. [33] shown an non-significant reduction of 0.27 kg/m2. This disagreement may be related to the inclusion of newest clinical trials in Pontes et al. [31], such as Hajipoor [34], Majewska [28], Michael [35], Skrypnik [9] et al. Our studies included a clinical trial published in 2021 [27] which not included in before reviews. Energy restriction is the necessary condition for BMI decrease [32], all studies designed in overweight or obese postmenopausal women weren’t accompanied with intervention restriction, this may be related to our non-significant result. Agreement with Karine’s funding [31], our study showed a reduction in serum insulin and HOMA-IR level, suggesting a possible beneficial role in the sensitivity of insulin. The effect of probiotics on glucose was not significant, it’s also consisted with previous study [31]. The potential mechanisms may be the gut microbiota is modified by probiotics supplementation and have an effect on modulating glucose metabolism [36]. Glucagon-like peptide (GLP)-1 is released by gut enteroendocrine L cells and can take direct actions on hepatocytes by activating genes involved in fatty acid β-oxidation and insulin sensitivity [36, 37]. Probiotics may influence inflammatory pathways and insulin sensitivity by modifying the gut microbiome and the concentration of plasma lipopolysaccharides [38]. There also showed the improvements in body adiposity, lipid profile and inflammatory biomarkers, but these improvements were not significant. For these factors, the number of current studies is small, and the results of meta-analysis need to be interpreted with caution and explained by more studies in the future.
There were some strengths of this systematic review. First, this was the first systematic review to evaluate the effects of probiotics in overweight or obese postmenopausal women. Second, the study included in this systematic review were recently published between 2015 to 2021. Third, all the studies were considered good by Cochrane recommendations and most outcomes showed a low or moderate level of heterogeneity. This study also had some limitations. First, the number of studies met the including criteria of is few, we had better include more clinical trials to make an evaluate about administration of probiotics in the future. Second, because of fewer than 10 studies with the same endpoint, we didn’t analysis publication bias, it’s too low to distinguish chance from real asymmetry.