Table 2 Summary of the human studies investigating the effects of fasting on gut microbiota alterations
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 12Â 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 Lachnospiraceae ↓Prevotellaceae ↓body weight, fat mass & blood glucose. ↑urea, creatinine | 1/5 |