Riboflavin Supplementation Promotes Butyrate Production in the Absence of Gross Compositional Changes in the Gut Microbiota

Microbial micronutrient sharing, gut redox balance and keystone taxa as a basis for a new perspective to solutions targeting health from the gut

In health, the gut microbiome functions as a stable ecosystem maintaining overall balance and ensuring its own survival against environmental stressors through complex microbial interaction. This balance and protection from stressors is maintained through interactions both within the bacterial ecosystem as well as with its host. As a consequence, the gut microbiome plays a critical role in various physiological processes including maintaining the structure and function of the gut barrier, educating the gut immune system, and modulating the gut motor, digestive/absorptive, as well as neuroendocrine system all of which are crucial for human health and disease pathogenesis. Pre- and probiotics, widely available and clinically established, offer various health benefits primarily by beneficially modulating the gut microbiome. However, their clinical outcomes can vary significantly due to differences in host physiology, diets, individual microbiome compositions, and other environmental factors. This perspective paper highlights emerging scientific insights into the importance of microbial micronutrient sharing, gut redox balance, keystone species, and the gut barrier in maintaining a diverse and functional microbial ecosystem, and their relevance to human health. We propose a novel approach that targets microbial ecosystems and keystone taxa performance by supplying microbial micronutrients in the form of colon-delivered vitamins, and precision prebiotics [e.g. human milk oligosaccharides (HMOs) or synthetic glycans] as components of precisely tailored ingredient combinations to optimize human health. Such a strategy may effectively support and stabilize microbial ecosystems, providing a more robust and consistent approach across various individuals and environmental conditions, thus, overcoming the limitations of current single biotic solutions.

Extreme winter environment dominates gut microbiota and metabolome of white-lipped deer

Qinghai-Tibet Plateau (QTP) is marked by harsh environments that drive the evolution of unique nutrient metabolism mechanism in indigenous animal gut microbiotas. Yet, responses of these microbiotas to different extreme environments remain poorly understood. White-lipped deer (Przewalskium albirostris), a native endangered species in the QTP, serves as an ideal model to study how gut microbiotas adapt to season and human disturbances. Here, a multi-omics integrated analysis of 16S rRNA, metagenomics, and untargeted metabolomics was performed to investigate the composition, function, and metabolic characteristics of gut microbiota in White-lipped deer across different seasons and living environments. Our results revealed that extreme winter environment dominated the composition, function, and metabolism of gut microbiota in white-lipped deer. The white-lipped deer exhibited an enriched gut microbiota associated with producing short-chain fatty acids in winter, with core feature genera including norank_o_Rhodospirillales, Rikenellaceae_RC9_gut_group, and unclassified_c_Clostridia. However, potential pathogenic bacteria and few short-chain fatty acid producers, with core feature genera including norank_f_p-2534-18B5_gut_group, Cellulosilyticum, and Paeniclostridium, showed enrichment in captivity. Pathways associated with carbohydrate metabolism, amino acid metabolism, and immune regulation showed enrichment in winter group as an adaptation to the cold and food scarcity. Among these, Rikenellaceae_RC9_gut_group and unclassified_c_Clostridia contributed significantly to these metabolic pathways. The gut microbiota of white-lipped deer exhibited enrichment in pathways related to intestinal inflammation and enhanced immune regulation to alleviate the stress of captivity. Among these, norank_f_p-2534-18B5_gut_group contributed the most to these pathways. Butyric, valeric, and valproic acids were significantly more abundant in the winter group, while 3-hydroxybutyric and (S)-beta-aminoisobutyric acids were higher in the captive group. Furthermore, enriched metabolites and associated pathways in both groups further supported the inferences on metagenomic functions. This study confirms the key role of specific gut microbiota in adapting to high-altitude winters and anthropogenic disturbances, emphasizing its importance for environmental resilience in wild, high-altitude mammals.

Nanoparticle-mediated sodium butyrate delivery for repairing hypoxic-ischemic brain injury in premature infants

Hypoxic-ischemic encephalopathy of prematurity (HIEP) is a leading cause of acute mortality and chronic neurological injury in premature infants. This study investigates the molecular mechanisms by which magnetic fluorescent nanoparticles loaded with sodium butyrate (MNs@SB) repair HIEP by modulating the Sp1 and TGF-β1 signaling pathways. Untargeted metabolomics analysis revealed significant suppression of the butyrate metabolism pathway in the intestinal tissues of HIEP mice. We synthesized and characterized MNs@SB nanoparticles, with zeta potential and DLS results indicating an average nanoparticle size of approximately 79.89 nm and a zeta potential of -36.87 mV. TEM images confirmed that the nanoparticles formed polymer-coated clusters. MNs@SB demonstrated excellent biocompatibility and stable magnetic targeting behavior. The nanoparticles were delivered to the brain via tail vein injection and magnetic targeting, with focused ultrasound facilitating their diffusion. The results showed that HIEP mice exhibited a significant increase in infarct size and extensive tissue loss, whereas MNs@SB treatment effectively reversed HIEP-induced brain damage, improving both short-term and long-term neurological deficits. Single-cell RNA sequencing and high-throughput transcriptome analysis revealed that MNs@SB promoted brain repair by upregulating neuronal Sp1, activating the TGF-β1 signaling pathway, and inhibiting neuronal apoptosis. In vivo experiments further confirmed that MNs@SB treatment restored SP1 mRNA and protein expression in the brain. Additionally, MNs@SB treatment significantly restored TGF-β1, p-SMAD2, and p-SMAD3 protein expression, indicating activation of the TGF-β1/SMAD2/3 signaling pathway. This study presents a novel nanomedicine therapeutic strategy with potential clinical applications.

Association between dietary consumption of multiple vitamins and age-related macular degeneration: a cross-sectional observational study in the National Health and Nutrition Examination Survey 2005-2008

Purpose

Age-related macular degeneration (AMD) is one of the common causes of blindness in the elderly worldwide. Its prevention and monitoring indicators remain a key area of research. This study aims to examine the association between vitamin intake and AMD prevalence.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2008 were used for cross-sectional analysis. Logistic regression models, subgroup analyses and multicollinearity regression were employed to assess the association between vitamin intake and AMD.

Results

A total of 1,627 participants were included, with 54.5% (weighted) males and 45.5% (weighted) females. Significant differences were observed in the intake of vitamins B (B1, B2, B6, and B12), E, and folic acid between the AMD and Non-AMD groups. The Non-AMD group had higher average intakes (weighted) of vitamin B1 (1.71 ± 1.10 vs. 1.37 ± 0.64), B2 (2.42 ± 1.22 vs. 1.86 ± 0.70), B6 (2.05 ± 1.25 vs. 1.71 ± 0.85), B12 (5.73 ± 6.18 vs. 4.54 ± 3.27), E (7.93 ± 5.47 vs. 6.39 ± 2.86), and folic acid (181.87 ± 178.04 vs. 140.72 ± 124.60). Logistic regression and subgroup analyses further supported these findings.

Conclusion

This study found that higher vitamin intakes B and E were associated with a lower prevalence of AMD in the U.S. population. Eating a healthy diet rich in vitamins B and E, particularly B2 (eggs, green vegetables, meat, mushrooms, and almonds) may help to reduce vision loss due to AMD. However, since this is a cross-sectional study, causal associations between vitamin intake and AMD cannot be established. Further randomized clinical trials are needed to confirm these findings.

Coevolution of specific gut microbiota of Min pig with host cold adaptation through enhanced vitamin B1 synthesis

Min pigs exhibit remarkable cold tolerance, where vitamin B1 synthesis by gut microbiota is crucial for the host's energy metabolism. However, the role of this synthesis in cold adaptation of Min pigs are not yet fully understood. This study utilized 16S rRNA amplicon and metagenomic sequencing to examine seasonal variations in the gut microbiota of Min pigs. Results indicated a significant rise in microbial diversity in winter, with the Bacteroidetes group being the most notably increased. The vitamin B1 biosynthetic pathway was significantly enriched during winter, with six significantly upregulated genes (ThiC, ThiD, ThiE, ThiG, ThiH, and ThiL) showing strong evidence of purifying selection. Among the six vitamin B1 synthesis genes significantly upregulated during winter, the increase was mainly due to a marked elevation in several sequences from specific microbial species. Binding energy analysis revealed that, except for ThiL, the average substrate binding energy of the top 10 sequences with the largest seasonal differences was significantly lower than those of the 10 sequences with the smallest differences. Furthermore, most of these sequences were uniquely prevalent in Min pigs and were not found in the homologous sequences of Duroc pigs. Bacteroidetes and Bacteroidales were identified as the primary contributors to these gene sequences. This research provides valuable insights for developing innovative cold-resistant feed and probiotics.

Meta-analysis of shotgun sequencing of gut microbiota in Parkinson's disease

We aimed to identify gut microbial features in Parkinson's disease (PD) across countries by meta-analyzing our fecal shotgun sequencing dataset of 94 PD patients and 73 controls in Japan with five previously reported datasets from USA, Germany, China1, China2, and Taiwan. GC-MS and LC-MS/MS assays were established to quantify fecal short-chain fatty acids (SCFAs) and fecal polyamines, respectively. α-Diversity was increased in PD across six datasets. Taxonomic analysis showed that species Akkermansia muciniphila was increased in PD, while species Roseburia intestinalis and Faecalibacterium prausnitzii were decreased in PD. Pathway analysis showed that genes in the biosyntheses of riboflavin and biotin were markedly decreased in PD after adjusting for confounding factors. Five out of six categories in carbohydrate-active enzymes (CAZymes) were decreased in PD. Metabolomic analysis of our fecal samples revealed that fecal SCFAs and polyamines were significantly decreased in PD. Genes in the riboflavin and biotin biosyntheses were positively correlated with the fecal concentrations of SCFAs and polyamines. Bacteria that accounted for the decreased riboflavin biosynthesis in Japan, the USA, and Germany were different from those in China1, China2, and Taiwan. Similarly, different bacteria accounted for decreased biotin biosynthesis in the two country groups. We postulate that decreased SCFAs and polyamines reduce the intestinal mucus layer, which subsequently facilitates the formation of abnormal α-synuclein fibrils in the intestinal neural plexus in PD, and also cause neuroinflammation in PD.

Homemade blenderized tube feeding improves gut microbiome communities in children with enteral nutrition

Enteral nutrition for children is supplied through nasogastric or gastrostomy tubes. Diet not only influences nutritional intake but also interacts with the composition and function of the gut microbiota. Homemade blenderized tube feeding has been administered to children receiving enteral nutrition, in addition to ready-made tube feeding. The purpose of this study was to evaluate the oral/gut microbial communities in children receiving enteral nutrition with or without homemade blenderized tube feeding. Among a total of 30 children, 6 receiving mainly ready-made tube feeding (RTF) and 5 receiving mainly homemade blenderized tube feeding (HBTF) were analyzed in this study. Oral and gut microbiota community profiles were evaluated through 16S rRNA sequencing of saliva and fecal samples. The α-diversity representing the number of observed features, Shannon index, and Chao1 in the gut were significantly increased in HBTF only in the gut microbiome but not in the oral microbiome. In addition, the relative abundances of the phylum Proteobacteria, class Gammaproteobacteria, and genus Escherichia-Shigella were significantly low, whereas that of the genus Ruminococcus was significantly high in the gut of children with HBTF, indicating HBTF altered the gut microbial composition and reducing health risks. Metagenome prediction showed enrichment of carbon fixation pathways in prokaryotes at oral and gut microbiomes in children receiving HBTF. In addition, more complex network structures were observed in the oral cavity and gut in the HBTF group than in the RTF group. In conclusion, HBTF not only provides satisfaction and enjoyment during meals with the family but also alters the gut microbial composition to a healthy state.

Effects of ileocolonic delivered vitamin B2, B3 and C (ColoVit) or the Groningen anti-inflammatory diet on disease course and microbiome of patients with Crohn's disease (VITA-GrAID study): a protocol for a randomised and partially blinded trial

BACKGROUND

Diet plays a pivotal role in the onset and progression of Crohn's disease (CD). Nutritional interventions revealed effects on intestinal inflammation and gut microbial composition. However, data from well-designed and controlled dietary trials are lacking. Therefore, evidence-based dietary recommendations are still unavailable to patients and physicians. Here, we aim to investigate the effects of an evidence-based anti-inflammatory diet, and an ileocolonic-targeted capsule containing vitamin B₂, B₃ and C (ColoVit) on patients with CD and their healthy household members.

METHODS AND ANALYSIS

In this multicentre, randomised, placebo-controlled, partially blinded nutritional intervention trial, we aim to recruit 255 CD patients with Harvey-Bradshaw Index <8 and a faecal calprotectin (FCal) cut-off of ≥100 µg/g at baseline. Participants will be randomised into two experimental intervention groups and one placebo group. In the experimental groups, participants will either adhere to the Groningen anti-inflammatory diet (GrAID) or ingest an ileocolonic-delivered oral vitamin B₂/B₃/C capsule (ColoVit). The study consists of a 12-week controlled interventional phase, which proceeds to a 9-month observational follow-up phase in which patients allocated to the GrAID group will be requested to continue the intervention on their own accord. Household members of participating patients will be asked to participate in the trial as healthy subjects and are allocated to the same group as their peer. The primary study outcome for patients is the change in FCal level from baseline. The primary outcome for household members is the change in gut microbial composition, which is set as secondary outcome for patients.

ETHICS AND DISSEMINATION

The protocol has been approved by the Institutional Review Board of the Stichting Beoordeling Ethiek Biomedisch Onderzoek in Assen, the Netherlands. Written informed consent will be obtained from all participants. Results will be disseminated through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

NCT04913467.

Intermediate role of gut microbiota in vitamin B nutrition and its influences on human health

Vitamin B consists of a group of water-soluble micronutrients that are mainly derived from the daily diet. They serve as cofactors, mediating multiple metabolic pathways in humans. As an integrated part of human health, gut microbiota could produce, consume, and even compete for vitamin B with the host. The interplay between gut microbiota and the host might be a crucial factor affecting the absorbing processes of vitamin B. On the other hand, vitamin B supplementation or deficiency might impact the growth of specific bacteria, resulting in changes in the composition and function of gut microbiota. Together, the interplay between vitamin B and gut microbiota might systemically contribute to human health. In this review, we summarized the interactions between vitamin B and gut microbiota and tried to reveal the underlying mechanism so that we can have a better understanding of its role in human health.

The effect of riboflavin supplementation on the systemic redox status in healthy volunteers: A post-hoc analysis of the RIBOGUT trial

BACKGROUND

Riboflavin is a redox-active vitamin that plays a pivotal role in human energy metabolism. Riboflavin may have beneficial health effects by increasing extracellular antioxidant capacity, thereby alleviating oxidative stress. Reduced levels of free thiols in blood reflect systemic oxidative stress, since they are readily oxidized by reactive species. In this study, we aimed to study the potential of riboflavin supplementation to improve the systemic redox status in healthy volunteers.

METHODS

This study was a post-hoc analysis of the RIBOGUT study, a randomized, double-blind, placebo-controlled human intervention trial that investigated the effect of riboflavin supplements on the gut microbiota composition of healthy individuals. Serum free thiols were quantified before and after intervention and adjusted to serum albumin levels. Changes in albumin-adjusted free thiols were analyzed, as well as potential associations with routine laboratory parameters and faecal bacterial quantification by fluorescence in-situ hybridization (FISH).

RESULTS

Participants were randomized to either placebo (n = 34), riboflavin 50 mg daily (n = 32), or riboflavin 100 mg daily (n = 33). At baseline, no significant differences in albumin-adjusted serum free thiols were observed. After intervention with either placebo or riboflavin, albumin-adjusted serum free thiols did not significantly change (P > 0.05), however, observed changes were inversely associated with changes in C-reactive protein (CRP) levels (r = -0.22, P < 0.05). At baseline, albumin-adjusted serum free thiols were positively associated with faecal relative abundances of Faecalibacterium prausnitzii (P < 0.01).

CONCLUSION

Riboflavin did not change the systemic redox status in healthy individuals as reflected by serum free thiols, but observed changes in albumin-adjusted free thiol levels were negatively associated with changes in CRP levels. Strikingly, albumin-adjusted free thiols were independently associated with relative abundances of faecal F. prausnitzii, which may suggest a potential host redox-microbiota interaction.