Table 3.

Fiber, gut microbiota, and metabolic regulation in overweight and obese individuals. Significant results are indicated by an up/down arrow.

Study	Subject Characteristics	Study Design	Intervention	Changes Related to Gut Microbiota	Changes Related to Metabolic Regulation
Chambers et al., Gut, 2019 [38]	n = 12, BMI 30, 60 yaer, M/F	3 × 42 days crossover	(1) High cellulose (20 g/day) (2) High inulin (20 g/day) (3) Inulin-propionate ester (IPE) (20 g/day)	IPE and inulin compared to cellulose: ↓ Diversity of bacterial species Inulin compared to cellulose: ↓ Enrichment (changes in evenness), ↔ Phyla level, ↑ Actinobacteria, Anaerostipes hadrus, Bifidobacterium faecale, Bacteroides caccae ↓ Clostridia, Clostridiales, Blautia obeum, Blautia luti, Oscillibacter spp., Blautia faecis, Ruminococcus faecis IPE compared to cellulose: ↔ Phyla level,↑ Bacteroides uniformis, Bacteroides xylanisolvens, ↓ Blautia obeum, Eubacterium ruminantium ↑ Propionate (% in serum), ↔ propionate (uM in feces and serum, % in feces), acetate (% and uM in feces and serum), butyrate (% and uM in feces and serum) IPE compared to inulin: ↔ Phyla level, ↑ Fusicatenibacter saccharivorans, ↓ Anaerostipes hadrus, Blautia faecale, Prevotelle copri	IPE and Inulin compared with cellulose: ↓ Ins, HOMA-IR, AT-IR, ↑ Matsuda ISI
Kjølbæk et al., Clin Nutr, 2019 [36]	n = 27, BMI 25–40, 18–60 yaer, M/F	2 × 4 weeks Crossover	(1) n3 PUFA (3.6 g/day) (2) Arabinoxylan oligosaccharides (10.4 g/day)	Within groups: (2) in responders: ↑ Actinobacteria, Eubacterium rectale, Faecalibacterium prusnitzii, Bifidobacterium faecale, Bifidobacterium stercoris, Bifidobacterium dolescentis, Blautia wexlerae, Bifidobacterium angulatum, Bifidobacterium merycicum, Bifidobacterium pseudocatenulatum, Bifidobacterium catenulatum, Fusicatenibacter saccharivorans, Bifidobacterium longum, Ruminococcus obeum, Dorea longgicaterna, Eubacterium hallii, Blautia luti ↓ Clostridium methylpentosum, Anaerotruncus colihominis, Erysipelothrix rhusiopathiae	↔ Glu, Ins, HOMA-IR, HOMA-β ↔ TC, HDL-C, LDL-C, VLDL-C, ApoB
Schutte et al., Am J Clin Nutr, 2018 [39]	n = 50, BMI 25–35, 61 year, M/F	12 weeks Parallel	(1) Refined wheat (98 g/day) (2) Whole-grain wheat (98 g/day)	↑ α-diversity, ↔ Lachnospiraceae and Ruminovoccaceae (and genera within these families)	↔ Glu, Ins, HOMA-IR ↔ TC, HDL-C, TG, NEFA ↓ IHTG
Canfora et al., Gastroenterology, 2017 [37]	n = 44, BMI 28–40, pre-diabetic, 45–70 year, M/F	12 weeks Parallel	(1) Maltodextrin (15 g/day) (2) Galacto oligosaccharides (15 g/day)	↑ Bifidobacterium spp., Prevotella oralis, Prevotella melaninogenica ↓ Bacteroides stercoris, Sutterella wadsworthia ↔ Fecal microbial richness or diversity ↔ SCFA (fecal and plasma)	↔ Glu, Ins, HOMA-IR, GLP-1 ↔ TG, NEFA
Lambert et al., Clin Nutr, 2017 [41]	n = 50, BMI 33, 44 year, M/F	12 weeks Parallel	(1) Wafers without pea fiber (2) Wafers with pea fiber (15 g/day)	↔ Total bacteria, Bacteroides/Prevotella spp., Bifidobacterium spp., Enterobacteriaceae, Methanobrevibacter spp., Firmicutes, Lactobacillus spp., Clostridium leptum (C-IV), Clostridium coccoides (C-XIVa), Clostridium cluster I, Clostridium cluster XI, Roseburia spp.	↔ Glu, Ins, HbA1c ↔ TC, LDL-C, HDL-C, TG, TC/HDL-C ratio
Weickert et al., Nutr Metab, 2011 [40]	n = 69, BMI >30, 55.3 year, M/F	18 weeks, Parallel	(1) Control diet (fiber 14 g/day) (2) High cereal-fiber diet, HCF (fiber 43 g/day) (3) High protein diet, HP (28 E% protein, 14 g/day fiber) (4) Combined HCF and HP diet (23 E% protein, 26 g/day fiber)	↔ Dominant groups of gut bacteria ↔ Fecal acetate, propionate, butyrate, valerate Within groups: (3) ↑ Valerate	Within groups (2) ↑ Ins sensitivity (Euglycaemic hyperinsulinaemic clamps)

Significant differences (p ≤ 0.05) between intervention group(s) and the control group are shown with ↑ or ↓ while ↔ indicates no significant difference. When several the intervention groups are present, the results for each group are indicated with the number. Fasting values are shown, if not otherwise stated. The control group is referred to as (1). AT-IR: Adipose tissue insulin resistance, BMI: body mass index, F: Female, GLP-1: Glucagon-like peptide 1, Glu: Glucose, g: gram, HbA1c: Glycated hemoglobin A1c, HCF: High cereal-fiber diet, HP: High protein diet, HDL-C: HDL-Cholesterol, HOMA-IR: Homeostasis assessment model-insulin resistance, Ins: Insulin, IHTG: Intrahepatic triglycerides, IPE: Inulin-propionate ester, LDL-C: LDL-Cholesterol, M: Male, Matsuda ISI: Matsuda insulin sensitivity index, n: numbers, NEFA: Non-esterified fatty acids, TG: Triglycerides, TC: Total cholesterol.