. 2023 May 17;20(10):5845. doi: 10.3390/ijerph20105845

Table 1.

Clinical evidence of gut microbiota improvements on degenerative changes associated with ageing.

Author [Ref]	Treatment	Methodology	Results
Liu et al. [173]	Probiotics, prebiotics, or synbiotics consumption	The study of physiological and molecular changes in aging male Wistar rats aged 8–24 months, analyzing body composition, muscular activity, blood biochemistry, and gut microbiota.	Significant increase in serum calcium levels after consumption of probiotics, prebiotics, or synbiotics compared to the control group. (0.52 mg/dL, 95% CI, p = 0.13, I² = 44%). There was no significant difference neither in the bone density of the participants (−0.04 g/cm²; 95% CI; p = 0.47; I² = 0%) nor in the PTH, OC, and ALP levels, respectively (0.71 pg/mL; 95% CI; p = 0.09; I² = 59%), (1.80 ng/mL; 95% CI; p = 0.66, I² = 0%), and (−10.64 U/L; 95% CI; p = 0.0010; I² = 86%).
Tabrizi et al. [177]	Consumption of probiotics and/or synbiotics	Meta-analysis of 18 RCTs performed in adults with diabetes providing detailed information on inflammatory markers such as IL-6, TNF-α, CRP, and NO after probiotics and/or synbiotics administration compared to a control group.	Decreased levels of TNF-α (SMD = −2.99; 95% CI; p = 0.001; I²: 96.3) and CRP p (SMD = −0.87; 95% CI; p < 0.001; I²: 90.2) with increased levels of NO (SMD = 1.49; 95% CI; p < 0.001; I²: 92.1) after supplementing participants with probiotics and/or synbiotics. On the other hand, there was no significant change in IL-6 levels (SMD = −0.65; 95% CI; p = 0.306; I²: 94.7).
Miller et al. [179]	Consumption of probiotics based on Bifidobacterium animalis ssp. lactis HN019	Meta-analysis of 4 controlled trials involving 527 participants supplemented with Bifidobacterium animalis ssp. lactis HN019 using low-fat milk as a vehicle for 3 to 6 weeks.	An increase in the phagocytic capacity of PMNs was observed (MDS = 0.74; 95% CI; p < 0.001) in addition to a moderate increase in the tumoricidal activity of NK cells (MDS = 0.43; 95% CI: 0.08; p = 0.02).
Zhong et al. [187]	Physical activity	RCT with 14 female participants divided into a control group and a second group which performed an aerobic and resistance exercise program for eight weeks.	Increase in the phylum Fusobacteria in the control group (F = 5.257, p = 0.045). In addition, a significant difference was observed in Betaproteobacteria abundance between both groups (F = 5.149; p = 0.047) and a decrease in the Bifidobacteriales order in the control group (F = 7.624, p = 0.020).
Ghosh et al. [190]	Nutritional changes	Multicenter RCT with 612 participants (286 men, 326 women) divided into a control group and a second group to which a Mediterranean diet was administered for 12 months, separated into three groups: non-fragile, pre-fragile, and fragile.	A significant decrease in DietNegative Otus was found in all groups. However, dietPositive OTUs increased significantly in the non-fragile group compared to the fragile group. In addition, markers of DietPositive OTUs showed a negative association with levels of inflammatory markers such as IL-17.
Ntemiri et al. [191]	Nutritional changes	A pilot study with 17 women divided into two groups (young and old) who consumed 38 g of freeze-dried cranberry powder daily for six weeks.	The β diversity of the faecal microbiota of older women formed a distinct cluster; however, the sample size, along with its interindividual variability, the trend was considered non-significant (PERMANOVA R2 = 0.03). However, an increase in certain CAGs associated with favourable species was identified.