Background
Materials and methods
Literature search
Study selection
Data extraction
Quality assessment
Quantitative data synthesis
Nonlinear dose–response analysis
Subgroup analyses
Publication bias and sensitivity analysis
GRADE certainty of the body of evidence
Results
Flow and characteristics of the included studies
References, country | Participants | Intervention | Comparison | Outcomea | Study design | |||||
---|---|---|---|---|---|---|---|---|---|---|
N (I/C) | Age | Gender | BMI | Population | Type | Dosage | ||||
Alles [21], Netherlands | 20 (20/20) | 59 | M-9 F-11 | 28.3 ± 3.5 | T2DM | FOS | 15 g/days (20 days) | Glucose | ↔FBG | C, RCT, SB |
Asemi [22], Iran | 54 (27/27) | 35–70 | M and F | 30.4 ± 5.3 | T2DM | Inulin and Lactobacillus sporogenes | 8.4 g/days (56 days) | L. sporogenes bread | ↔FBG, ↓FINS, HbA1c | P, RCT, DB |
Behrouz [23], Iran | 59 (29/30) | 20–60 | M and F | 25–40 | Nonalcoholic fatty liver disease | Oligofructose and probiotic | 16 g/days (84 days) | Maltodextrin | ↔FBG, FINS, HbA1c | P, RCT, DB |
Bomhof [24], Canada | 14 (8/6) | ≥ 18 | M-8 F-6 | > 25 | non-alcoholic steatohepatitis with overweight | Oligofructose | 16 g/days (252 days) | Maltodextrin | ↔FINS, HOMA-IR, ↑FBG | P, RCT, DB |
Bonsu [25], Canada | 26 (12/14) | > 40 | M and F | 30.3 ± 4.4 | T2DM | Inulin | 10 g/days (84 days) | Xylitol | ↔FBG, HOMA-IR | P, RCT, DB |
Canfora [26], Netherlands | 44 (21/23) | 45–70 | M and F | 28–40 | Overweight or obese | GOS | 15 g/days (84 days) | Maltodextrin | ↔FBG, FINS | P, RCT, DB |
Daubioul [27], Italy | 7 (7/7) | 48–60 | M and F | 21.7–37.6 | Non-alcoholic steatohepatitis | FOS | 16 g/days (56 days) | Maltodextrin | ↔FBG, FINS | C, RCT, DB |
de Luis [28], Spain | 32 (16/16) | 25–60 | M and F | 30–35 | Obese | FOS | 9.84 g/days (30 days) | Control cookie | ↔FBG, FINS, HbA1c | P, RCT, DB |
Dehghan [31], Iran | 52 (27/25) | 20–65 | F-only | 25–34.99 | T2DM | Oligofructose and inulin | 10 g/days (56 days) | Maltodextrin | ↓FBG, HOMA-IR | P, RCT, TB |
Dehghan [32], Iran | 49 (24/25) | 20–65 | F-only | > 25 | T2DM | Inulin | 10 g/days (56 days) | Maltodextrin | ↓FBG, FINS, HbA1c, HOMA-IR | P, RCT, DB |
Dehghan [29], Iran | 49 (27/22) | 30–65 | F-only | 25–34.99 | T2DM | Oligofructose and inulin | 10 g/days (60 days) | Maltodextrin | ↓FBG, HOMA-IR, ↔ FINS | P, RCT, DB |
Dewulf [32], Belgium | 30 (15/15) | 18–65 | F-only | > 30 | Obese | Inulin and oligofructose | 16 g/days (90 days) | Maltodextrin | ↔FBG, FINS, HbA1c, HOMA-IR | P, RCT, DB |
Forcheron [33], France | 17 (9/8) | 31.7 ± 4.0 | M-6 F-11 | ND | Healthy | Inulin and oligofructose | 10 g/days (180 days) | Maltodextrin | ↔FBG, FINS | P, RCT, DB |
Gargari [34], Iran | 49 (24/25) | 20–65 | F-only | 25–35 | T2DM | Inulin | 10 g/days (60 days) | Maltodextrin | ↓FBG, FINS, HbA1c, HOMA-IR | P, RCT, TB |
Ghavami [35], Iran | 46 (23/23) | 30–50 | M and F | 25–35 | T2DM | Inulin | 10 g/days (42 days) | Starch | ↔FBG, FINS, HbA1c, ↓HOMA-IR | P, RCT, DB |
Giacco [36], Italy | 30 (30/30) | 45.5 ± 9.9 | M-20 F-10 | 26.6 ± 2.2 | Mild hypercholesterolaemia | FOS | 10.6 g/days (60 days) | Maltodextrine plus aspartame | ↔FBG | C, RCT, DB |
Guess [37], UK | 38 (20/18) | > 18 | M and F | 25–35 | Prediabetes | Inulin | 30 g/days (126 days) | Cellulose | ↓FBG, FINS, HbA1c | P, RCT, DB |
Guess [38], UK | 34 (34/34) | ≥ 18 | M and F | 25–35 | Overweight subjects with prediabetes | Inulin | 30 g/days (42 days) | Cellulose | ↔FINS, ↓HbA1c | C, RCT, DB |
Jackson [39], UK | 54 (27/27) | 35–65 | M and F | 20–32 | Healthy | Inulin | 10 g/days (56 days) | Maltodextrin | ↔FBG, FINS | P, RCT, DB |
Javadi [40], Iran | 38 (19/19) | 20–60 | M and F | 30.7 ± 3.7 | Non-alcoholic steatohepatitis | Inulin | 10 g/days (90 days) | Maltodextrin | ↔FBG, ↓FINS, HbA1c | P, RCT, DB |
Luo [41], France | 12 (12/12) | 19–32 | M-only | 21.0 ± 1.7 | Healthy | FOS | 20 g/days (28 days) | Sucrose | ↔FBG, FINS | C, RCT, DB |
Luo [42], Belgium | 10 (10/10) | 57.0 ± 6.3 | M-6 F-4 | 28.0 ± 3.2 | T2DM | FOS | 20 g/days (28 days) | Sucrose | ↔FBG, FINS, HOMA-IR | C, RCT, DB |
Meksawan [43], Thailand | 9 (9/9) | > 50 | M-5 F-4 | ND | Elderly CAPD patients | FOS | 20 g/days (30 days) | Sucrose | ↔FBG | C, RCT, DB |
Parnell [44], Canada | 39 (21/18) | 20–70 | M and F | >25 | Overweight or obese | Oligofructose | 21 g/days (84 days) | Maltodextrin | ↔FBG | P, RCT, DB |
Pedersen [45], UK | 29 (14/15) | 42–65 | M-only | 28.2 ± 1.0 | T2DM | GOS | 5.5 g/days (84 days) | Maltodextrin | ↔FBG, FINS, HbA1c, HOMA-IR | P, RCT, DB |
Rajkumar [46], India | 30 (15/15) | 20–25 | M-14 F-16 | 18.5–24.9 | Healthy | FOS and L. salivarius | 10 g/days (42 days) | L. salivarius | ↔FBG, FINS, HbA1c | P, RCT, SB |
Roshanravan [47], Iran | 30 (15/15) | 30–55 | M and F | 27–35 | T2DM | Inulin | 10 g/days (45 days) | Starch | ↔FBG, FINS, HbA1c, HOMA-IR | P, RCT, DB |
Russo [48], Italy | 15 (15/15) | 18.8 ± 0.7 | M-only | 22.8 ± 2.3 | Healthy | Inulin | 11 g/days (35 days) | Control pasta | ↔FBG, HbA1c, HOMA-IR, ↑FINS | C, RCT, DB |
Scheid [49], Brazil | 72 (35/37) | 67.1 ± 6.1 | M and F | 27.9 ± 5.0 | Elderly | FOS | 7.4 g/days (63 days) | Maltodextrin | ↔FBG, FINS, HbA1c | P, RCT, DB |
Shakeri [50], Iran | 52 (26/26) | 53 | M and F | 30.3 ± 5.3 | T2DM | Inulin and Lactobacillus sporogenes | 8.4 g/days (56 days) | Lactobacillus sporogenes control breads | ↔FBG | P, RCT, DB |
Tovar [51], Mexican | 59 (30/29) | 18–50 | F-only | ≥ 25 | Obese | Inulin | 10 g/days (90 days) | No treatment | ↔FBG | P, RCT, DB |
Tripkovic [52], UK | 10 (10/10) | 30–55 | M-only | 25–35 | Overweight | Inulin | 15 g/days (28 days) | Control bread rolls | ↔FBG, FINS, HbA1c | C, RCT, DB |
Vulevic [53], UK | 45 (45/45) | 18–65 | M-16 F-29 | > 25 | Overweight | GOS | 5.5 g/days (84 days) | Maltodextrin | ↔FBG, ↓FINS | C, RCT, DB |
Study quality
Main outcomes and GRADE certainty
Quality assessment | Summary of findings | Quality of evidence | |||||||
---|---|---|---|---|---|---|---|---|---|
Outcomes | Risk of bias | Inconsistency | Indirectness | Imprecision | Publication Bias | Number of intervention/control | Absolute effect (95% CI) | Relative effecta intervention/control | |
FBG (Total population) | No serious limitations | Serious limitationsb | No serious limitations | No serious limitations | No serious limitations | 656/651 | − 0.21 (− 0.33, − 0.09) mmol/l | − 4.32%/0.36% | ⊕ ⊕ ⊕○ moderate |
HbA1C (Total population) | No serious limitations | Serious limitationsc | No serious limitations | No serious limitations | No serious limitations | 220/219 | − 0.39 (− 0.65, − 0.13) % | − 4.93%/1.20% | ⊕ ⊕ ⊕○ moderate |
FINS (Total population) | No serious limitations | Very serious limitationsd | No serious limitations | No serious limitations | Strongly suspectede | 515/514 | − 1.22 (− 1.90, − 0.54) μU/ml | − 12.62%/0.44% | ⊕ ○○○ very low |
HOMA-IR (Total population) | No serious limitations | Very serious imitationsf | No serious limitations | No serious limitations | No serious limitations | 357/360 | − 0.57 (− 0.84, − 0.31) | − 19.10%/− 1.27% | ⊕ ⊕ ○○ low |
FBG (T2DM and prediabetes) | No serious limitations | No serious limitations | No serious limitations | No serious limitations | No serious limitations | 283/280 | − 0.60 (− 0.71, − 0.48) mmol/l | − 7.41%/− 0.26% | ⊕ ⊕ ⊕ ⊕ high |
HbA1C (T2DM and prediabetes) | No serious limitations | No serious limitations | No serious limitations | No serious limitations | No serious limitations | 190/189 | − 0.58 (− 0.83, − 0.32) % | − 5.15%/1.55% | ⊕ ⊕ ⊕ ⊕ high |
FINS (T2DM and prediabetes) | No serious limitations | Very serious limitationsg | No serious limitations | No serious limitations | No serious limitations | 232/229 | − 1.75 (-2.87, − 0.63) μU/ml | − 20.08%/− 3.50% | ⊕ ⊕ ○○ low |
HOMA-IR (T2DM and prediabetes) | No serious limitations | Very serious limitationsh | No serious limitations | No serious limitations | No serious limitations | 195/197 | − 0.69 (− 1.10, − 0.28) | − 27.63%/− 2.29% | ⊕ ⊕ ○○ low |
Nonlinear dose–response analysis
Subgroup analyses
Subgroups | Fasting blood glucose (mmol/l) | HbA1c (%) | FINS (μU/ml) | HOMA-IR | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
n | WMD (95% CI) | Pa | I2 (%) | Pb | n | WMD (95% CI) | Pa | I2 (%) | Pb | n | WMD (95% CI) | Pa | I2 (%) | Pb | n | WMD (95% CI) | Pa | I2 (%) | Pb | |
Sex | ||||||||||||||||||||
Male | 4 | − 0.15 (− 0.32, 0.03) | 0.106 | 0.0 | 0.599 | 2 | − 0.18 (− 0.41, 0.05) | 0.120 | 0.0 | 0.599 | 4 | 0.90 (0.30, 1.51) | 0.004 | 71.2 | < 0.001 | 3 | − 0.09 (− 0.83, 0.66) | 0.819 | 40.9 | 0.184 |
Female | 6 | − 0.51 (− 0.87, − 0.16) | 0.004 | 81.7 | < 0.001 | 5 | − 0.56 (− 0.97, − 0.15) | 0.008 | 72.3 | 0.006 | 4 | − 0.37 (− 5.70, − 1.86) | < 0.001 | 47.7 | 0.125 | 3 | − 1.84 (− 2.72, − 0.97) | < 0.001 | 56.9 | 0.098 |
ITF type | ||||||||||||||||||||
Inulin | 12 | − 0.28 (− 0.51, − 0.06) | 0.012 | 74.5 | < 0.001 | 7 | − 0.48 (− 0.85, − 0.12) | 0.010 | 47.6 | 0.076 | 11 | − 1.20 (− 2.14, − 0.27) | 0.012 | 84.5 | < 0.001 | 10 | − 0.63 (− 0.94, − 0.31) | < 0.001 | 76.9 | < 0.001 |
Other kinds | 21 | − 0.15 (− 0.27, − 0.03) | 0.011 | 25.3 | 0.142 | 5 | − 0.28 (− 0.71, 0.14) | 0.193 | 61.5 | 0.035 | 15 | − 1.32 (− 2.07, − 0.56) | 0.001 | 0.0 | 0.754 | 8 | − 0.42 (− 0.92, 0.09) | 0.108 | 18.9 | 0.281 |
Food based | ||||||||||||||||||||
ITF in drink | 25 | − 0.24 (− 0.39, − 0.09) | 0.002 | 66.9 | < 0.001 | 11 | − 0.42 (− 0.74, − 0.11) | 0.008 | 52.2 | 0.022 | 20 | − 1.38 (− 2.06, − 0.70) | < 0.001 | 61.1 | < 0.001 | 14 | − 0.58 (− 0.87, − 0.28) | < 0.001 | 70.4 | < 0.001 |
Others | 8 | − 0.12 (− 0.26, 0.03) | 0.114 | 0.0 | 0.945 | 1 | − 0.20 (− 0.44, 0.04) | 0.101 | ~ | ~ | 6 | − 0.28 (− 2.08, 1.51) | 0.757 | 46.4 | 0.097 | 4 | − 0.62 (− 1.27, 0.04) | 0.067 | 9.2 | 0.347 |
Intervention type | ||||||||||||||||||||
ITF vs non-ITF | 29 | − 0.22 (− 0.35, − 0.10) | 0.001 | 60.5 | < 0.001 | 12 | − 0.39 (− 0.65, − 0.13) | 0.004 | 51.2 | 0.020 | 23 | − 1.08 (− 1.81, − 0.36) | 0.003 | 69.4 | < 0.001 | 15 | − 0.53 (− 0.81, − 0.25) | < 0.001 | 68.7 | < 0.001 |
Synbiotics vs. probiotic | 4 | 0.01 (− 0.21, 0.23) | 0.944 | 0.0 | 0.697 | 3 | − 2.10 (− 3.80, − 0.39) | 0.016 | 34.5 | 0.217 | 3 | − 1.16 (− 2.02, − 0.29) | 0.009 | 0.0 | 0.928 | |||||
Study design | ||||||||||||||||||||
Parallel | 24 | − 0.23 (− 0.39, − 0.08) | 0.003 | 68.9 | < 0.001 | 10 | − 0.45 (− 0.77, − 0.13) | 0.006 | 55.4 | 0.017 | 19 | − 1.48 (− 2.25, − 0.71) | < 0.001 | 63.2 | < 0.001 | 15 | − 0.58 (− 0.89, − 0.28) | < 0.001 | 69.5 | < 0.001 |
Cross-over | 9 | − 0.15 (− 0.30, − 0.01) | 0.038 | 0.0 | 0.962 | 2 | − 0.19 (− 0.42, 0.05) | 0.117 | 0.0 | 0.590 | 7 | − 0.32 (− 1.57, 0.92) | 0.612 | 62.7 | 0.013 | 3 | − 0.63 (− 1.07, − 0.19) | 0.005 | 0.0 | 0.629 |
Country of study | ||||||||||||||||||||
Iran | 11 | − 0.59 (− 0.83, − 0.35) | < 0.001 | 31.1 | 0.151 | 7 | − 0.75 (− 1.00, − 0.50) | < 0.001 | 0.0 | 0.919 | 9 | − 1.95 (− 3.18, − 0.73) | 0.002 | 80.4 | < 0.001 | 8 | − 0.82 (− 1.30, − 0.34) | 0.001 | 82.1 | < 0.001 |
Other countries | 22 | − 0.10 (− 0.22, 0.02) | 0.116 | 58.8 | < 0.001 | 5 | − 0.08 (− 0.27, 0.11) | 0.399 | 0.0 | 0.586 | 17 | − 0.76 (− 1.56, 0.04) | 0.062 | 52.8 | 0.006 | 10 | − 0.48 (− 0.66, − 0.29) | < 0.001 | 0.0 | 0.523 |
Sponsor referred | ||||||||||||||||||||
No | 25 | − 0.27 (− 0.41, − 0.13) | < 0.001 | 60.0 | < 0.001 | 11 | − 0.42 (− 0.70, − 0.15) | 0.003 | 54.0 | 0.017 | 20 | − 1.32 (− 2.10, − 0.55) | 0.001 | 74.0 | < 0.001 | 13 | − 0.63 (− 0.92, − 0.34) | < 0.001 | 70.2 | < 0.001 |
Yes | 8 | − 0.01 (− 0.14, 0.13) | 0.920 | 0.0 | 0.791 | 1 | 0.00 (− 0.71, 0.71) | 1.000 | ~ | ~ | 6 | − 1.01 (− 2.19, 0.17) | 0.093 | 7.9 | 0.366 | 5 | − 0.30 (− 1.04, 0.44) | 0.422 | 37.8 | 0.169 |
Sensitivity analysis
Subgroupsa | FBG (mmol/l) | HbA1c (%) | FINS (μU/ml) | HOMA-IR | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
n | WMD (95% CI) | Pb | I2 (%) | Pc | n | WMD (95% CI) | Pb | I2 (%) | Pc | n | WMD (95% CI) | Pb | I2 (%) | Pc | n | WMD (95% CI) | Pb | I2 (%) | Pc | |
Healthy-subjects | 5 | − 0.04 (− 0.18, 0.09) | 0.513 | 0.0 | 0.447 | 5 | − 0.10 (− 1.29, 1.10) | 0.874 | 59.8 | 0.041 | 2 | − 0.76 (− 1.53, 0.02) | 0.056 | 0.0 | 0.830 | |||||
T2DM and prediabetes | 11 | − 0.58 (− 0.86, − 0.31) | < 0.001 | 0.0 | 0.672 | 7 | − 0.37 (− 0.71, − 0.02) | 0.036 | 18.7 | 0.287 | 8 | − 1.14 (− 2.05, − 0.23) | 0.014 | 49.7 | 0.052 | 6 | − 0.47 (− 0.64, − 0.30) | < 0.001 | 39.3 | 0.143 |
Overweight and obesity | 7 | − 0.08 (− 0.18, 0.02) | 0.126 | 0.0 | 0.748 | 5 | − 1.54 (− 3.11, 0.03) | 0.054 | 0.0 | 0.844 | 3 | − 0.38 (− 1.20, 0.43) | 0.353 | 0.0 | 0.391 | |||||
Others | 7 | − 0.08 (− 0.18, 0.02) | 0.419 | 0.0 | 0.748 | 1 | − 0.20 (− 0.44, 0.04) | 0.101 | ~ | ~ | 5 | − 1.14 (− 1.93, − 0.34) | 0.005 | 0.0 | 0.655 | 4 | − 0.31 (− 0.55, − 0.08) | 0.010 | 0.0 | 0.883 |
Total | 30 | − 0.10 (− 0.18, − 0.03) | 0.005 | 4.4 | 0.397 | 8 | − 0.25 (− 0.45, − 0.06) | 0.011 | 12.5 | 0.333 | 23 | − 0.89 (− 1.50, − 0.28) | 0.004 | 51.6 | 0.002 | 15 | − 0.43 (− 0.56, − 0.29) | < 0.001 | 0.0 | 0.553 |