Table 3.
Differences in the relative abundance of bacteria at phylum level.
| Study ID (Author, Year) | Comparison Groups 1 | Actinobacteria 1 | Bacteroidetes 1 | Firmicutes 1 | Fusobacterium 1 | Proteobacteria 1 | Verrucomicrobia 1 | Other | B/F 2 or F/B 3 Ratio 1 |
|---|---|---|---|---|---|---|---|---|---|
| Andoh 2016 [17] | O vs. L | No significant differences in O vs. L | No significant differences in O vs. L O: 31.2 ± 14.1% L: 32.9 ± 6.4% p = 0.38 |
Significantly higher in O vs. L O: 42.6 ± 8.5% L: 35.1 ± 5.2% p = 0.018 |
Significantly higher in O vs. L O: 1.86 ± 4.20% L: 0.00 ± 0.00% p = 0.002 |
No significant differences in O vs. L | — | Unclassified (p > 0.05) | B/F 1 ratio O: 0.86 ± 0.63 L: 0.96 ± 0.27 Not significant |
| Beaumont 2016 [37] | — | — | — | — | — | — | — | — | — |
| Borges 2018 [38] | — | — | — | — | — | — | — | — | — |
| Borgo 2018 [18] | O vs. NW | No significant differences in O vs. NW O: 1.5 ± 1.2 NW: 1.4 ± 1.9 |
No significant differences in O vs. NW O: 38.5 ± 12.7NW: 41.7 ± 7.9 | No significant differences in O vs. NW O: 53.8 ± 11.3 NW: 51.2 ± 8.1 |
— | No significant differences in O vs. NW O: 3.5 ± 2.7 NW: 4.5 ± 5.7 |
No significant differences in O vs. NW O: 2.4 ± 5.3 NW: 0.9 ± 1.7 |
— | — |
| Chavez-Carbajal 2019 [19] | O + MetS vs. O vs. NW | No significant differences between groups O: 1.27% O + MetS: 1.29% NW: 2.32% p = 0.1667 |
No significant differences between groups O: 22.50% O + MetS: 23.43% NW: 36.20% p = 0.7125 |
Significantly higher in O vs. NW O: 72.97% O + MetS: 73.34% NW: 56.95% p = 0.0029 |
— | No significant differences between groups O: 2.80% O + MetS: 1.45% NW: 4.20% p = 0.1160 |
— | Includes Verrucomicrobia, Spirochaetes and Fusobacteria. O: 0.22% O + MetS: 0.37% NW: 0.14% p < 0.0001 |
F/B2 ratio O + MetS: 3.13 O: 3.24 C: 1.57 p = not reported (significance not reported) |
| Chen 2016 [20] | O vs. NW | — | No significant differences in O vs. NW O: 4.339 × 10−1 NW: 5.004 × 10−1 q = 0.080 |
No significant differences in O vs. NW O: 5.226 × 10−1 NW: 4.660 × 10−1 q = 0.080 |
No significant differences in O vs. NW O: 1.433 × 10−2 NW: 1.446 × 10−3 q = 0.080 |
— | — | Chrisiogenetes: O: 1.927 × 10−5 NW: 1.680 × 10−4 q = 0.080 |
— |
| Davis 2016 [40] | — | — | — | — | — | — | — | — | — |
| Davis 2020 [39] | — | — | — | — | — | — | — | — | — |
| De la Cuesta-Zuluaga 2018 [41,42] | O vs. OW vs. NW | — | Significantly lower in O vs. NW O: 8.2 ± 14.1 OW: 10.8 ± 17 NW:11.5 ± 19.8 p = 0.04 |
No significant differences between groups O: 53.9 ± 30.9 OW: 51.8 ± 29.5 NW: 48.5 ± 20.8 p = 0.62 |
— | — | — | — | Significantly lower in O vs. NW B/F 1 ratio O: 0.15 ± 0.28 OW: 0.22 ± 0.42 NW: 0.23 ± 0.40 p = 0.04 |
| Fei 2019 [43] | — | — | — | — | — | — | — | — | — |
| Finucane 2014 [44] | O vs. L | No differences | No differences (p = 0.30) | No differences (p = 0.86) | No differences | No differences | — | No differences | — |
| Gallè 2020 [45] | O/OW vs. NW/UW | — | No significant differences in O/OW vs. NW/UW O/OW: 31.8 ± 8.9 NW/UW: 33.4 ± 10.4 p = 0.54 |
No significant differences in O/OW vs. NW/UW O/OW: 61.1 ± 8.7 NW/UW: 58.9 ± 13.1 p = 0.47 |
— | — | — | — | No significant differences in O/WO vs. NW/UW F/B 2 ratio O/OW: 2.2 ± 1.3 NW/UW: 2.1 ± 1.1 p = 0.56 |
| Gao 2018 [46] | O vs. OW vs. NW vs. UW | No differences in O vs. UW | Significantly higher in O vs. UW (p < 0.05) |
No differences in O vs. UW | Significantly higher in O vs. UW (p < 0.01) |
Significantly higher in O vs. UW (p < 0.05) |
— | — | — |
| Harakeh 2020 [47] | O vs. NW | — | — | — | Significantly lower in O vs. NW (p = 0.005, FDR = 0.014) |
— | — | — | — |
| Kaplan 2019 [48] | — | — | — | — | — | — | — | — | — |
| Kasai 2015 [21] | O vs. NO | No differences between groups O: 8.0 ± 7.1% NO: 8.2 ± 6.7% p = 0.917 |
Significantly lower in O vs. NO O: 37.0 ± 14.0% NO: 44.0 ± 9.8% p = 0.033 |
No differences between groups O: 40.8 ± 15.0% NO: 37.0 ± 9.1% p = 0.241 |
O: 1.58% NO: 0.07% p > 0.05 |
O: 0.91% NO: 1.20% p > 0.05 |
— | Increase in the proportion of “unclassified” phyla (O 21.76% vs. NO 8.54%) were observed in the O group relative to the NO group Sinergistetes: O: 0.00% NO: 0.03% |
Significantly higher in O vs. UW F/B 2 ratio O: 1.7 ± 1.7 NO: 0.9 ± 0.4 p = 0.045 |
| Loftfield 2020 [49] | O vs. NW | — | Significantly higher in O vs. NW | — | — | — | — | — | No significant differences in O vs. NW F/B 2 ratio expressed as beta coefficients OW vs. NW: −29.7 (p = 0.26) O vs. NW: 4.66 (p = 0.88) |
| Oduaran 2020 [34] | O vs. L | No differences between groups (p > 0.05) | Significantly higher in O vs. L (p < 0.05) | No differences between groups (p > 0.05) | No differences between groups (p > 0.05) | No differences between groups (p > 0.05) | No differences between groups (p > 0.05) | No differences between groups (p > 0.05) | — |
| Org 2017 [50] | — | — | — | — | — | — | — | — | — |
| Osborne 2020 [51] | — | — | — | — | — | — | — | — | — |
| Ozato 2019 [32] | G1: BMI < 20 G2: 20 ≤ BMI < 25 G3: 25 ≤ BMI < 30 G4: BMI ≥ 30 |
No differences between groups | Significant decrease across BMI groups in women (p for trend: <0.001). No significant association across BMI groups in men | Significant increase across BMI groups in women (p for trend: 0.004). No significant association across BMI groups in men | — | No differences between groups | — | — | — |
| Patil 2012 [52] | O vs. L | No differences between groups | No differences between groups | No differences between groups | — | No differences between groups | — | Unclassified: No differences between groups | — |
| Peters 2018 [33] | O vs. OW vs. NW | — | Not associated with BMI category (p = 0.49) | Not associated with BMI category (p = 0.40) | — | — | — | — | F/B 2 ratio (Kruskal-Wallis test p = 0.94). No results per group provided |
| Rahat-Rozenbloom 2014 [53] | O/OW vs. L | — | No significant differences in O/OW (6.4 ± 4.3) vs. L (19.4 ± 6.1) p = 0.335 |
Significantly higher in O/OW (83.1 ± 4.1) vs. L (69.5 ± 5.8) p = 0.008 |
— | — | — | — | Significantly higher in O/OW vs. LF/B 2 ratio O/OW: 34.3 ± 1.6 L: 6.8 ± 1.0 (p = 0.023, or p = 0.0098 when adjusted for age). F/B 2 ratio expressed as a base 2 logarithm derived from the median center log-ratio-transformed values of each sample. |
| Salah 2019 [54] | O vs. OD vs. D vs. NW | Significant differences: NW: 0.54% O: 0.69% D: 0.77% OD: 1.52% p = 0.04 |
Non-significant differences: NW:34.25% O: 44.94% D: 38.4% OD: 37.16% p = 0.07 |
Non-significant differences: NW. 36.4% O: 48.72% D: 49.1% OD: 51.09% p = 0.31 |
Non-significant differences: NW: 0% O: 0% D: 0% O + D: 0.48 p = 0.20 |
Significant differences NW: 24.65% O: 5.61% D: 11.1% OD: 7.48% p = 0.02 |
Significant differences NW: 3.86% O: 0.006% D: 0.43% OD: 1.54% p < 0.001 |
Significant differences: Euryarchaeota (p < 0.001) Lentisphaerae (p = 0.01) Synergistetes (p < 0.001) Tenericutes (p = 0.01) |
No significant differences reported: F/B 2 ratio NW = 1.06 O: 1.08 OD: 1.37 p = not reported |
| Thingholm 2019 [55] | — | — | — | — | — | — | — | — | — |
| Verdam 2013 [56] | O vs. NO | — | Significantly lower in O vs. NO O: 5.9% ± 5.8% NO: 19.2% ± 9.2%; p < 0.002 |
Significantly higher in O vs. NO O: 85.8% ± 8.5% NO: 74.6% ± 9.2%; q = 0.002 |
— | Several members of the Proteobacteria including those related to E. aerogene, K. pneumoniea, Vibrio, and Yersina spp. were positively associated with BMI and more abundantly present in obese | — | — | B/F 1 ratio strongly decreased in O (p = 0.0002). |
| Vieira-Silva 2020 [57] | — | — | — | — | — | — | — | — | — |
| Whisner 2018 [58] | BMI < 18.5 BMI 18.5–24.9 BMI 25.0–29.9 BMI ≥ 30.0 |
— | — | — | — | — | — | — | F/B 2 ratio did not differ by BMI p = 0.413 No results per group provided |
| Wilkins 2019 [59] | — | — | — | — | — | — | — | — | — |
| Yasir 2015 [35] | O vs. NW (France) O vs. NW (Saudi Arabia) |
No significant differences (France and SA) | Significantly higher in O vs. NW (France) (p = 0.05) No significant differences (SA) |
No significant differences (France) Significantly higher in O vs. NW (SA) (p = 0.001) |
— | Significantly higher in O vs. NW (France) (p = 0.002) No significant differences (SA 4) |
No significant differences (France and SA) | — | — |
| Yun 2017 [60] | O vs. OW vs. NW | — | — | — | — | — | — | — | No significant differences in F/B 2 ratio. No results per group provided |
1 D: diabetes; G1–4; Groups 1–4; L: lean; NO: non-obese; NW: normal weight; O: obese; OD: obesity and diabetes; O+MetS: obesity and metabolic syndrome; OW: overweight; UW: underweight; 2 B/F ratio: Bacteroidetes to Firmicutes ratio; 3 F/B ratio: Firmicutes to Bacteroidetes ratio; 4 SA: Saudi Arabia. N.A.: not available.