In a new review published in the journal Nutrients, researchers reviewed preclinical and clinical data to analyze gut microbial changes across a variety of nutritional conditions.
To work: Beneficial Effects of Dietary Interventions on the Gut Microbiota—A Current Critical Review and Future Perspectives. Image Credit: LightField Studios/Shutterstock.com
Background
Intermittent fasting (IF), a popular dietary intervention, has been studied for its impact on gut microbial composition and host physiopathological processes.
Research shows that dietary components modulate the gut microbial community and that nutrient transformations in microbes profoundly affect host metabolism.
This interrelationship can potentially significantly impact human health and disease by influencing the metabolism of chronic drugs. Dietary interventions for a variety of disorders can be tailored to improve overall health by restoring gut microbial balance and diversity.
About the review
In this review, researchers identified the impact of diet on the gut microbiome by examining preclinical and clinical studies published in the English-language PubMed database from 2015 to 2023. For preclinical data, only studies published between 2021 and 2023 were included.
Two researchers independently performed the data screening and discrepancies were resolved by consensus. Protocols, studies and case reports for which full text was not available were excluded and eligible records were subjected to full text screening. In total, 17 preclinical records and 26 clinical records were analyzed.
Preclinical studies on the effects of dietary intervention on the intestinal microbiota of animals
Increased high-fat diet (HF) and CR interventions in six-week-old C57BL/6J mice Firmicutes, actinobacteria, Firmicutes: Bacteroidetes ratio, Bifidobacteria, Lactobacillus johnsonii, Bifidobacterium pseudolongumAnd fecalibaculum abundance in the cecum. However, these interventions have diminished. Bacteroidetes And parabacteroids sort of.
In male Fisher 344 x Brown Norway hybrid F1 rats, time-restricted feeding (TRF) Keto diets reduced feces actinobacteria And patessibacteria counts and increases Verrucomicrobi sort of. Western diet TRF (16:8) reduced stool Bacteroidota, ProteobacteriaAnd cyanobacteria Counts while increasing Verrucomicrobi sort of.
Regular meal diet increased TRF lactobacillus, Muribaculaceae, Dubosiella, Clostridia, And fecalibacteria sort of. The diet of the mother who applied intermittent fasting (M-IF) was reduced Lactobacillus intestinal abundance in mouse pups.
IF was reduced in male Wistar rats Firmicutes: Bacteroidetes rate and Bacillus velezensis counts increased Lachnospiraceae And lactobacilli the counts increased and lactobacillus And Akkermansia muciniphila sort of. CR and IF increased Helicobacter, BacteroidetesAnd Firmicutes counted while decreasing in rainbow trout actinobacteria counted in the proximal intestine.
16:8 and 24:24 IF intervention increased and decreased the abundance of various microorganisms in the feces of allergic mice. Firmicutes sort of. Short term IF reduced Firmicutes, Verrucomicrobi, Lachnospiraceae, ruminococcaceaeAnd ruminiclostridium Long-term IF was reduced when counts were performed in C57BL/6 mice with induced colitis Akkermansiaceae and increased lactobacilli sort of.
Preclinical studies on gut microbial composition in C57BL/6J mice found that it adapted to dietary changes. However, the results lacked consistency and homogeneity in terms of bacterial strains/group dynamics.
Different types of fasting have different effects on gut microbes, and inferences are difficult to make due to study protocols that included various dietary restrictions, durations, and diets. Additionally, evaluations were conducted in various animal models that may be particularly sensitive to caloric restriction (CR).
Effects of dietary interventions on human gut microbiota
A randomized controlled trial (RCT) reported that Buchinger fasting for five days increased Proteobacteria And Christensenellaceae counted but reduced Firmicutes: Bacteroides ratio. Fasting reduced to water only fusobacterium increased count and homogeneous intestinal microbiota.
Ramadan intermittent fasting increased alpha diversity, LachnospiraceaeAnd ruminococcaceae counted but decreased bacteroidals. Other studies have shown reduced intermittent fasting during Ramadan. coprococcus, Clostridium_XlV spp. And Lachnospiraceae counted but increased Dorea, Klebsiella, fecalibacteria, Sutterella, parabacteroids, Alistipes, bacteroids, And Firmicutes sort of.
Ten-day Buchinger fast and three-month refeeding reduced Firmicutes counted but increased bacteroids, ProteobacteriaAnd bacteroids. For hypertensive patients with metabolic syndrome, the Buchinger fast followed by a Mediterranean-like diet may reduce this reduction. Bifidobacterium, Coprococcus is coming, And roseburia sort of.
VLCD increases over 46 days in obese postmenopausal women Christensenellaceae sort of. Six-week calorie restriction and weight stabilization diet in overweight and obese adults, Akkermansia muciniphila sort of.
Dietary restriction may affect the gut microbiota by reducing pro-inflammatory cytokines, increasing short-chain fatty acid (SCFA) production, increasing intestinal barrier integrity, and exerting immunomodulatory effects.
Long-term dietary restriction reduced for one year actinobacteria counts and Firmicutes: Bacteroidetes while the rate increases bacteroids, roseburia, fecalibacteriaAnd Clostridium XIVa ratio. No obvious pattern of changes in the gut microbiota has been identified; however, the health benefits were clear, including reduced risk factors for age-related diseases and increased life expectancy.
Based on the review findings, the effects of dietary interventions, such as time-restricted fasting and calorie restriction, on metabolic health markers and gut microbiota composition were investigated. These programs alter the intestinal environment by altering nutrient availability, energy sources, microbial growth, and SCFA production.
They can reduce inflammation, regulate metabolism and improve circadian rhythm. However, data are insufficient to establish a typical pattern of changes in the gut microbiota.
Further research is needed to determine long-term changes and evaluate different gut microbiota molecules, especially in obese and metabolically poor patients.