Table 1

Effects of interventions with dietary fibre, carbohydrates and protein and changes in dietary patterns on gut microbiota and host metabolism in healthy, overweight, obese and insulin resistant individuals

DietStudy designFunctional outcomesGut microbiota composition and functionalityIndividualsReference
Dietary protein
High protein/moderate CHO (HPMC) and HP/low CHO (HPLC)28-day, randomised, cross-over designHPMC and HPLC: increased faecal branched-chain fatty acids and concentrations of phenylacetic acid and N-nitroso compoundsHPMC: no significant changes
HPLC: ↓ Roseburia, Eubacterium rectale, Bacteroides spp; no changes in Faecalibacterium prausnitzii
17 men with obesity (BMI: 30.0–48.5 kg/m2) 89
LC/higher protein isocaloric14 weeks, parallel designLiver fat ↓
Hepatic lipid metabolism↑
Inflammation ↓
Rapid microbial alterations:
Streptococcus, Lactococcus and Eggerthella
Ruminoccocus, Eubacterium, Clostridium and Bifidobacterium
10 adults with obesity/NAFLD
(BMI: 27–40 kg/m2)
162
Dietary fibre and carbohydrates
Barley kernel bread (37.6 g fibre/day)3 days, randomised cross-over design (vs white bread reference 9.1 g fibre/day)Increased plasma GLP-1, PYY, breath H2 excretion, fasting serum SCFAs, improved insulin sensitivity index (p<0.05)Increased Prevotella/Bacteroides ratio in responders versus non-responders (post hoc analysis)39 healthy adults (BMI: 18–28 kg/m2) 163 164
16 g oligofructose (8 g two times) per day2 weeks, placebo-controlled (16 g dextrin maltose), parallel designReduced 2-hour postprandial glucose AUC (p<0.05) Increased plasma GLP-1 and PYY levels and increased breath–hydrogen excretionNot determined10 healthy adults (BMI mean±SD: 21.6±0.99 kg/m2) 165
16 g FOS or GOS per day2 weeks, cross-over designIncreased fasting glucose Bifidobacterium ↑, FOS: butyrate-producing Phascolarctobacterium ↑, GOS: Ruminococcus35 healthy adults
(BMI <18 kg/m2)
23
RS versus NSP
(resp. 16 g NSP, 25 g RS vs 42 g NSP, 2.5 g RS)
3 weeks, randomised cross-over designInverse relationship gut microbiota diversity–dietary responsiveness↑ Ruminococcaceae and ↑ Lachnospiraceae14 men with MetS (BMI: 27.9–51.3 kg/m2) 124 166
30 g RS (10 g three times) per day4 weeks, placebo controlled (20 g digestible starch), two-way crossoverImproved whole-body insulin sensitivity (euglycaemic–hyperinsulinaemic clamp) (p<0.05).Not determined10 healthy adults (BMI: 18.4–32.3 kg/m2 167
16 g inulin/oligofructose mix (8 g two times) per day12 weeks, parallel design, placebo controlled (16 g maltodextrin)Reduced post-OGTT glucose response (7%, p<0.01); no effects on HOMA, fasting glucose and insulin and HbA1cBifidobacterium and F. prausnitzii, ↓ Bacteroides intestinalis, B. vulgatus and Propionibacterium 30 women with obesity (BMI, >30 kg/m2) 168
15 g GOS (5 g, three times) per day12 weeks, placebo-controlled
(isocaloric maltodextrin), parallel design
No effects on glucose or insulin homeostasis, no increases in fasting SCFA plasma concentrations or faecal SCFAsFivefold increase in faecal Bifidobacterium (p=0.009, q=0.144); no effect microbial richness or diversity44 adults with prediabetes andoverweight/obesity (BMI: 25–35 kg/m2) 22
5.5 g GOS mixture 1×/day12 weeks, placebo-controlled
(5.5 g maltodextrin), two-way crossover
Decreased fasting insulin (p<0.01), triglyceride and C reactive protein plasma concentrationsIncreased Bifidobacterium (p<0.0001)45 adults with overweight/obesity (BMI >25 kg/m2) 169
Dietary patterns
Animal-based diet (very low fibre) versus plant-based diet (high fibre)5 days, cross-over designAltered bile acid metabolism, plant polysaccharide fermentation ↓ Alistipes, Bilophila and Bacteroides
Roseburia, E. rectale and Ruminococcus bromii
10 healthy, lean and overweight adults (BMI: 19–32 kg/m2) 103
Mediterranean diet compared with energy-reduced Mediterranean diet and physical activity promotion1 yearBMI, fasting glucose, glycated haemoglobin and triglycerides ↓,
high-density cholesterol ↑
Butyricicoccus, Haemophilus, Ruminiclostridium 5 and E. hallii400 adults with MetS
(BMI ≥27 and ≤40 kg/m2)
113
  • AUC, area under the curve; BMI, body mass index; FOS, fructo-oligosaccharide; GLP-1, glucagon-like peptide 1; GOS, galacto-oligosaccharide; HOMA, homeostasis model assessment; HP, high protein; HPLC, high protein/low carbohydrate (CHO); HPMC, high protein/moderate carbohydrate (CHO); LC, low CHO; MetS, metabolic syndrome; NAFLD, non-alcoholic fatty liver disease; NSP, non-starch polysaccharide; OGTT, oral glucose tolerance test; PYY, peptide YY; RS, resistant starch; SCFA, short-chain fatty acid.