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Table 2 Summary of the human studies investigating the effects of fasting on gut microbiota alterations

From: Gut microbiota modulation as a possible mediating mechanism for fasting-induced alleviation of metabolic complications: a systematic review

First author, year Study design Study Subjects Intervention Biospecimen Microbiota analyzing methods Main findings Quality assessment score
Remely M, 2015 Intervention pre-post design 13 overweight individuals One-week Buchinger fasting program* with laxative treatment followed by a 6 week intervention with a probiotic formula Stool 16srDNA with a quantitative real time polymerase chain reaction No significant changes in total bacteria, or of Bacteroidetes, Prevotella, Clostridium cluster XIVa, or Clostridium cluster IV.Faecalibacterium prausnitzii, Akkermanisa and Bifidobacteria 1/5
He Y, 2019 Intervention pre-post design 16 healthy individuals, Age: 18–40 years six individuals subjected to a water-only fast and ten individuals receiving a juice fast, both for seven days Stool 16S ribosomal RNA gene Water-only fasting changed the bacterial community, ↑more homogenous gut microbiomes, ↓Fusobacterium. colorectal cancer 1/5
Mesnage R, 2019 Intervention pre-post design 15 healthy men, Age: 18–70 years 10 days Buchinger fasting program with daily energy intake of about 250 kcal and an enema every 2 days Stool 16S rRNA gene amplicon sequencing Lachnospiraceae,Ruminococcaceae. ↑ Bacteroidetes, Proteobacteria (Escherichia coli, Bilophila wadsworthia) 1/5
Ozkul C, 2019–2020** Intervention pre-post design 9 adult subjects Ramadan fasting consisting of 17 h of fasting/day during a 29-day period Stool qPCR assay A. muciniphila and B. fragilis ↓Serum fasting glucose and total cholesterol levels 1/5
  Stool 16S rRNA amplicon sequencing ↑Microbial richness. ↑Butyricicoccus, Bacteroides, Faecalibacterium, Roseburia, Allobaculum, Eubacterium, Dialister, Erysipelotrichi 1/5
Balogh A, 2020 Randomized controlled trial Hypertensive metabolic syndrome patients 1.control (n = 36) 2.fasting (n = 35) 1. Controls: Dietary Approach to Stop Hypertension (DASH) diet. 2. Buchinger fasting protocol followed by DASH diet for 5 days Stool 16S rRNA sequencing or shotgun sequencing Clostridial Firmicutes ↓butyrate producers such as F. prausnitzii, E. rectale and C. comes at first, which were reverted after three months. ↑ Odoribacter species ↑ propionate production capacity, mucin degradation gene modules 3/5
Gable K, 2020 Intervention pre-post design 14 obese adults a daily 8-h time restricted feeding (8-h feeding window/ 16-h fasting window) for 12 weeks Stool 16S rRNA gene sequencing Gut microbiota phylogenetic diversity remained unchanged. No significant alterations in any phyla 1/5
Lilja S, 2020 Randomized controlled single-blinded trial 154 healthy individuals 1.Buchinger fasting (n = 20) 2.fasting mimetic (n = 100) 3.control (n = 31) 1.Buchinger fasting: 250 cal a day for 5 days 2.Fasting mimetic: routine diet with supplement of prebiotic and secondary plant ingredients 3 months 3.controls: placebo Stool Ilumnia sequencing and mass spectrometry Buchinger fasting group: ↑distribution of Proteobacteria, ↓Firmicutes/Bacteroidetes ratio Fasting mimetic supplementation group: ↑Actinobacteria 3/5
Guo Y, 2021 Randomized controlled trial 39 patients with metabolic syndrome 1.control (n = 18) 2.fasting (n = 21) "2-day" modified fasting (69% calorie reduction compared to non-fasting days) for 8 weeks Stool 16S rRNA gene sequencing ↓fat mass, oxidative stress, inflammatory cytokines, ↑vasodilatory parameters. Significant changes in gut microbiota communities: ↑ Rumonococcaceae, Roseburia, and Clostridium ↑production of short-chain fatty acids, ↓ lipopolysaccharides 3/5
Maifeld A, 2021 Randomized controlled trial Hypertensive patients with metabolic syndrome 1.controls 2. fasting 1. Controls: Dietary Approach to Stop Hypertension (DASH) 2. fasting: 2 days 1200 kcal/day, 5-days 300–350 kcal/day derived from vegetables followed by a modified DASH Stool 16S rRNA gene sequencing Bifidobacterium, ↑Bacteroides & Anaerotruncus & Alistipes ↑Propionate production capacity, mucin degradation gene modules ↓body weight and blood pressure 3/5
Su J, 2021 Intervention pre-post design Healthy non obese young and middle age individuals from two cohorts 1.fasting (n = 57; 27 middle age & 30 young) 2. age- & body weight–matched controls (n = 10) Ramadan fasting consisting of 16 h of fasting/day during a 30-day period Control: routine diet/no fasting Stool 16S rRNA gene sequencing ↑Clostridiales, Lachnospiraceae and Ruminococcaceae families butyric acid–producing LachnospiraceaePrevotellaceae ↓body weight, fat mass & blood glucose. ↑urea, creatinine 1/5
  1. *Buchinger fasting program; Fat intake (g/d): 0.2, Protein intake (g/d): 1.8, Carbohydrate intake (g/d): 56.2, Fibre intake (g/d): 1.1, Energy intake (kcal/d): 234.4, Total fluid: 2–3 L per day
  2. **Results are published in two articles