Table 2.
Characteristics of the included studies
| First author (publication year) | Country |
Total sample size (M/F) |
Target population | Mean age (year) | Mean BMI (kg/m2) | RCT design (blinding) | Duration (weeks) | Intervention of experimental group (Dose) | Number of bacteria | Intervention of control group | ROB |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Tamtaji et al. (2019) | Iran | 79 | Alzheimer’s disease | 77.8 | 21.13 | Parallel (yes) | 12 weeks | Selenium (200 mg/day) plus probiotic containing L. acidophilus, B. bifidum, and Bifidobacterium longum (6 × 109 CFU/day) | 3 | Placebo | Good |
| Hlivak et al. (2005) | Slovakia | 7/31 | Elderly nursing home population | 76.7 | 29.24 | Parallel (yes) | 60 weeks | Selenium (50 µg/day) plus probiotic containing Enterococcus faecium (2 × 109 CFU/day) | 1 | Placebo | Fair |
| Raygan et al. (2019) | Iran | 21/33 | Patients with T2DM and CHD | 63.6 | 30.65 | Parallel (yes) | 12 weeks | Selenium (200 µg/day) plus probiotic containing Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus fermentum, and Bifidobacterium bifidum (8 × 109 CFU/day) | 4 | Placebo | Good |
| Jamilian et al. (2021) | Iran | 51 | Chronic Schizophrenia | 45.1 | 24.8 | Parallel (yes) | 12 weeks | Selenium (200 µg/day) plus probiotic containing Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus fermentum, and Bifidobacterium bifidum (8 × 109 CFU/day) | 4 | Placebo | Good |
| Shabani et al. (2018) | Iran | 60 F | Polycystic Ovary Syndrome | 27.2 | 25.15 | Parallel (yes) | 12 weeks | Selenium (200 µg/day) plus probiotic containing Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus fermentum, and Bifidobacterium bifidum (8 × 109 CFU/day) | 4 | Placebo | Good |
M male, F female, BMI body mass index, RCT randomized controlled trial, ROB risk of bias, T2DM type 2 diabetes mellitus, CHD coronary heart disease, CFU colony-forming unit