Table 3.
Modulation of dietary fiber on gut microbiota and metabolic outcomes in patients with type 2 diabetes.
| Author Year Region |
Subjects | F:M a Mean Age (years) |
RCT Design |
Fiber Type or Sources | Amount of Fiber (g/day) |
Duration of Intervention |
Change in Gut Microbiota b | Metabolic Effects b | Microbiome and metabolic Indicators |
|---|---|---|---|---|---|---|---|---|---|
| Pedersen, C. [129] (2016) UK |
29 well-controlled men | All men around 57 |
Double-blind | galacto-oligosaccharide (GOS) | 5.5 (n = 14) placebo (n = 15) |
12 weeks | ↑: α-diversity (Shannon and Simpson indices) ↑: Bifidobacterium (close to significance) |
No significant effect on glucose, insulin, or C-peptide fasting concentrations | Bifidobacterium positively correlated with total AUC of glucose and IL-6 |
| Gonai, M. [130] (2017) Japan |
52 patients | -- 50 ± 10 |
Double-blind | galacto-oligosaccharide (GOS) | 10 (n = 27) placebo (n = 25) |
4 weeks | ↓: α-diversity (Observed OTUs) ↑: Bifidobacteriaceae ↓: Lachnospiraceae, Ruminococcaceae, Peptostreptococcaceae, Erysipelotrichaceae, Porphyromonadaceae |
No clinical parameters changed significantly | Negative correlations of A1c with Bifidobacteriaceae and Peptostreptococcaceae; FPG with Peptostreptococcaceae; TG with Uminococcaceae; positive correlations of AST and ALT with Lachnospiraceae |
| Zhao, L. [65] (2018) China |
43 patients | -- 35–70 |
Open-label | fiber in diet | high-fiber diet (n = 27) usual care (n = 16) |
84 days | ↕: β-diversity (Bray-Curtis) ↑: Bifidobacterium spp. and other SCFA producers ↑: CAZyme-encoding genes for starch and inulin degradation ↑: fhs for acetate and but for butyrate formation pathway ↑: acetate and butyrate |
↓: A1c ↑: Postprandial insulin |
Higher acetate and butyrate coincided with a significantly greater AUC of postprandial glucagon-like peptide-1 and a higher level of fasting peptide YY, which partly improve A1c level |
| Birkeland, E. [131] (2020) Norway |
25 patients | 10:15 63.1 |
Double-blinded, crossover | inulin-type fructans | 16 placebo |
6-week intervention 4-week washout |
↔: α-diversity (observed OTUs) ↕: β-diversity ↑: Bifidobacterium adolescentis, Bacteroides ovatus, Faecalibacterium prausnitzii ↓: Ruminococcus ↑: SCFAs (acetic acid and propionic acid) |
Bifidobacterium adolescentis negatively related to fecal butyric acid | |
| Mitchell, C. M. [132] (2021) US |
22 adults at risk for T2D |
14:8 54.4 ± 8.3 |
Double-blind | Inulin | 10 (n = 13) placebo (n = 9) |
6 weeks | ↑: Bifidobacteria | ↓: Fasting insulin, HOMA-IR | No significant correlation between changes in bifidobacteria and any outcome variables. |
| Reimer, R. A. [133] (2021) Canada |
290 adult patients with overweight/obesity |
198:92 around 55 |
Double-blind | soluble viscous fiber | 15–20 (n = 147) isocaloric placebo (n = 143) |
52 weeks | ↑: Collinsella, Parabacteroides, Roseburia ↓: Faecalibacterium, Lactobacillus, Oscillibacter |
↓: A1c, BMI, WC, LDL | |
| Mateo-Gallego, R. [134] (2021) Spain |
14 patients with overweight or obesity | -- 56.1 ± 6.27 |
Double-blinded, crossover | isomaltulose + resistant dextrin | 16.5 + 5.28 placebo |
10-week intervention 6–8 weeks’ washout |
↔: α-diversity (Shannon, Pielou, Observed features) ↔: β-diversity (weighted Unifrac) ↑: Parabacteroides ↓: Bacteroides, Odoribacter, Butyricimonas, Oscillospira |
↓: BMI, Blood glucose, HOMA-IR |
a: Ratio of female subjects to male subjects; -- data not available. b: ↑ increased; ↓ decreased; ↔ unchanged; ↕ changed β-diversity.