A diet of U.S. military food rations alters gut microbiota composition and does not increase intestinal permeability

Ultra-Processed Foods: A Narrative Review of the Impact on the Human Gut Microbiome and Variations in Classification Methods

Ultra-processed foods (UPFs) are foods that are industrially processed and are often pre-packaged, convenient, energy-dense, and nutrient-poor. UPFs are widespread in the current Western diet and their proposed contribution to non-communicable diseases such as obesity and cardiovascular disease is supported by numerous studies. UPFs are hypothesized to affect the body in multiple ways, including by inducing changes in the gut microbiome. This review summarizes the available research on the effect of UPFs on the gut microbiome. We also review current usage of the NOVA food classification system in randomized controlled trials and observational studies and how its implementation effects UPF research. Despite some differences in methodology between studies, results often associate UPF consumption with a number of negative health consequences. There are attempts to standardize a UPF classification system; however, reaching and implementing a consensus is difficult. Future studies focusing on the mechanisms by which UPFs effect the body, including through the microbiome and metabolome, will be essential to refine our understanding of the effects of UPFs on human health.

Intestinal Microbiota Reduction Followed by Fasting Discloses Microbial Triggering of Inflammation in Rheumatoid Arthritis

Rheumatoid arthritis (RA) synovitis is dominated by monocytes/macrophages with inflammatory patterns resembling microbial stimulation. In search of triggers, we reduced the intestinal microbiome in 20 RA patients (open label study DRKS00014097) by bowel cleansing and 7-day fasting (≤250 kcal/day) and performed immune monitoring and microbiome sequencing. Patients with metabolic syndrome (n = 10) served as a non-inflammatory control group. Scores of disease activity (DAS28/SDAI) declined within a few days and were improved in 19 of 20 RA patients after breaking the fast (median ∆DAS28 = -1.23; ∆SDAI = -43%) or even achieved remission (DAS28 < 2.6/n = 6; SDAI < 3.3/n = 3). Cytometric profiling with 46 different surface markers revealed the most pronounced phenomenon in RA to be an initially increased monocyte turnover, which improved within a few days after microbiota reduction and fasting. Serum levels of IL-6 and zonulin, an indicator of mucosal barrier disruption, decreased significantly. Endogenous cortisol levels increased during fasting but were insufficient to explain the marked improvement. Sequencing of the intestinal microbiota indicated that fasting reduced potentially arthritogenic bacteria and changed the microbial composition to species with broader metabolic capabilities. More eukaryotic, predominantly fungal colonizers were observed in RA, suggesting possible involvement. This study demonstrates a direct link between the intestinal microbiota and RA-specific inflammation that could be etiologically relevant and would support targeted nutritional interventions against gut dysbiosis as a causal therapeutic approach.

In vitro gut microbiome response to carbohydrate supplementation is acutely affected by a sudden change in diet

BACKGROUND

Interactions between diet, stress and the gut microbiome are of interest as a means to modulate health and performance. Here, in vitro fermentation was used to explore the effects of a sudden change in diet, 21 days sole sustenance on the Meal, Ready-to-Eat (MRE) U.S. military combat ration, on inter-species competition and functional potential of the human gut microbiota. Human fecal samples collected before and after MRE intervention or consuming a habitual diet (HAB) were introduced to nutrient-rich media supplemented with starch for in vitro fermentation under ascending colon conditions. 16S rRNA amplicon and Whole-metagenome sequencing (WMS) were used to measure community composition and functional potential. Specific statistical analyses were implemented to detect changes in relative abundance from taxa, genes and pathways.

RESULTS

Differential changes in relative abundance of 11 taxa, Dorea, Lachnospira, Bacteroides fragilis, Akkermansia muciniphila, Bifidobacterium adolescentis, Betaproteobacteria, Enterobacteriaceae, Bacteroides egerthii, Ruminococcus bromii, Prevotella, and Slackia, and nine Carbohydrate-Active Enzymes, specifically GH13_14, over the 24 h fermentation were observed as a function of the diet intervention and correlated to specific taxa of interest.

CONCLUSIONS

These findings suggest that consuming MRE for 21 days acutely effects changes in gut microbiota structure in response to carbohydrate but may induce alterations in metabolic capacity. Additionally, these findings demonstrate the potential of starch as a candidate supplemental strategy to functionally modulate specific gut commensals during stress-induced states.

Effect of Intestinal Microbiota Transplantation on Intestinal Flora and Inflammatory Factor Levels in Patients with Ulcerative Colitis

Objective

The present study was performed to evaluate the effect of intestinal microbiota transplantation (IMT) on intestinal flora and inflammatory factor levels in patients with ulcerative colitis (UC).

Methods

In this study, 94 UC patients who attended the Department of Proctology or the Department of Gastroenterology departments of Sinopharm Dongfeng General Hospital between April 2021 and April 2022 were identified as research participants and were assigned to the control or Research Groups via the random number table method, with 47 cases in each group. Interventions included oral mesalamine for patients in the control group and oral mesalamine plus IMT for those in the research group. Outcome measures included clinical efficacy, intestinal microbiota score, enteroscopy score, Sutherland index, inflammatory factor level, intestinal mucosal barrier function level, and adverse reactions.

Results

Mesalamine plus IMT was associated with significantly higher treatment efficiency (97.8%) versus mesalamine alone (80.85%) (P<0.05). Mesalamine plus IMT provided a better intestinal microbiota balance and milder disease symptoms versus mesalamine, as evidenced by the significantly lower intestinal microbiota scores, colonoscopy scores, and Sutherland index (P<0.05). In post-treatment, patients with IMT exhibited more mitigated inflammatory responses than those without, as shown by the higher levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-17 (IL-17), and interleukin-23 (IL-23) (P<0.05). Significantly lower D-lactate and serum diamine oxidase (DAO) levels were observed after IMT intervention than those with mesalamine alone (P<0.05). IMT features no significant increase in adverse effects than the control group (P>0.05).

Conclusion

IMT efficiently ameliorates the intestinal microbiota conditions of UC patients, mitigates inflammatory responses in the body, and facilitates the restoration of intestinal mucosal barrier function with no significant increase in adverse effects.

The Fecal Metabolome Links Diet Composition, Foacidic positive ion conditions, chromatographicallyod Processing, and the Gut Microbiota to Gastrointestinal Health in a Randomized Trial of Adults Consuming a Processed Diet

BACKGROUND

Food processing alters diet digestibility and composition, thereby influencing interactions between host biology, diet, and the gut microbiota. The fecal metabolome offers insight into those relations by providing a readout of diet-microbiota interactions impacting host health.

OBJECTIVES

The aims were to determine the effects of consuming a processed diet on the fecal metabolome and to explore relations between changes in the fecal metabolome with fecal microbiota composition and gastrointestinal health markers.

METHODS

This was a secondary analysis of a randomized controlled trial wherein healthy adults [94% male; 18-61 y; BMI (kg/m²): 26 ± 3] consumed their usual diet [control (CON), n = 27] or a Meal, Ready-to-Eat^TM (Ameriqual Packaging) military ration diet composed of processed, shelf-stable, ready-to-eat items for 21 d (MRE; n = 27). Fecal metabolite profiles, fecal microbiota composition, biomarkers of intestinal barrier function, and gastrointestinal symptoms were measured before and after the intervention. Between-group differences and associations were assessed using nonparametric t tests, partial least-squares discriminant analysis, correlation, and redundancy analysis.

RESULTS

Fecal concentrations of multiple dipeptides [Mann-Whitney effect size (ES) = 0.27-0.50] and long-chain SFAs (ES = 0.35-0.58) increased, whereas plant-derived compounds (ES = 0.31-0.60) decreased in MRE versus CON (P < 0.05; q < 0.20). Changes in dipeptides correlated positively with changes in fecal concentrations of Maillard-reaction products (ρ = 0.29-0.70; P < 0.05) and inversely with changes in serum prealbumin (ρ = -0.30 to -0.48; P ≤ 0.03). Multiple bile acids, coffee and caffeine metabolites, and plant-derived compounds were associated with both fecal microbiota composition and gastrointestinal health markers, with changes in fecal microbiota composition explaining 26% of the variability within changes in gastrointestinal health-associated fecal metabolites (P = 0.001).

CONCLUSIONS

Changes in the fecal metabolomes of adults consuming a Meal, Ready-to-Eat^TM diet implicate interactions between diet composition, diet digestibility, and the gut microbiota as contributing to variability within gastrointestinal responses to the diet. Findings underscore the need to consider both food processing and nutrient composition when investigating the impact of diet-gut microbiota interactions on health outcomes. This trial was registered at www.

CLINICALTRIALS

gov as NCT02423551.

Dietary vitamin K is remodeled by gut microbiota and influences community composition

Vitamins have well-established roles in bacterial metabolism. Menaquinones (MKn, n = prenyl units in sidechain) are bacterially produced forms of vitamin K produced by the gut microbiota and consumed in the diet. Little is known about the influence of dietary vitamin K quinones on gut microbial composition and MKn production. Here, male and female C57BL6 mice were fed a vitamin K deficient diet or vitamin K sufficient diets containing phylloquinone (PK, plant-based vitamin K form), MK4, and/or MK9. DNA was extracted from cecal contents and 16S sequencing conducted to assess microbial composition. Cecal microbial community composition was significantly different in vitamin K deficient female mice compared to females on vitamin K sufficient diets (all p < .007). Parallel trends were seen in male mice, but were not statistically significant (all p > .05 but <0.1). Next, stable isotope-labeled vitamin K quinones were supplemented to male and female C57BL6 mice (²H₇PK, ¹³C₁₁MK4, ²H₇MK7, ²H₇MK9) and to an in vitro fermentation model inoculated with human stool (²H₇PK, ²H₇MK4, ²H₇MK9, or vitamin K precursor ²H₈-menadione). Vitamin K quinones in feces and culture aliquots were measured using LC-MS. In vivo, supplemented vitamin K quinones were remodeled to other MKn (²H₇- or ¹³C₆-labeled MK4, MK10, MK11, and MK12), but in vitro only the precursor ²H₈-menadione was remodeled to ²H₇MK4, ²H₇MK9, ²H₇MK10, and ²H₇MK11. These results suggest that dietary vitamin K deficiency alters the gut microbial community composition. Further studies are needed to determine if menadione generated by host metabolism may serve as an intermediate in dietary vitamin K remodeling in vivo.

Integrating Dietary Data into Microbiome Studies: A Step Forward for Nutri-Metaomics

Diet is recognised as the main driver of changes in gut microbiota. However, linking habitual dietary intake to microbiome composition and activity remains a challenge, leaving most microbiome studies with little or no dietary information. To fill this knowledge gap, we conducted two consecutive studies (n = 84: a first pilot study (n = 40) to build a web-based, semi-quantitative simplified FFQ (sFFQ) based on three 24-h dietary recalls (24HRs); a second study (n = 44) served to validate the newly developed sFFQ using three 24HRs as reference method and to relate gut microbiome profiling (16S rRNA gene) with the extracted dietary and lifestyle data. Relative validation analysis provided acceptable classification and agreement for 13 out of 24 (54%) food groups and 20 out of 29 nutrients (69%) based on intraclass correlation coefficient, cross-classification, Spearman's correlation, Wilcoxon test, and Bland-Altman. Microbiome analysis showed that higher diversity was positively associated with age, vaginal birth, and intake of fruit. In contrast, microbial diversity was negatively associated with BMI, processed meats, ready-to-eat meals, sodium, and saturated fat. Our analysis also revealed a correlation between food groups or nutrients and microbial composition. Overall, we provide the first dietary assessment tool to be validated and correlated with microbiome data for population studies.

Gut Microbiota in Military International Travelers with Doxycycline Malaria Prophylaxis: Towards the Risk of a Simpson Paradox in the Human Microbiome Field

Dysbiosis, developed upon antibiotic administration, results in loss of diversity and shifts in the abundance of gut microbes. Doxycycline is a tetracycline antibiotic widely used for malaria prophylaxis in travelers. We prospectively studied changes in the fecal microbiota of 15 French soldiers after a 4-month mission to Mali with doxycycline malaria prophylaxis, compared to changes in the microbiota of 28 soldiers deployed to Iraq and Lebanon without doxycycline. Stool samples were collected with clinical data before and after missions, and 16S rRNA sequenced on MiSeq targeting the V3-V4 region. Doxycycline exposure resulted in increased alpha-biodiversity and no significant beta-dissimilarities. It led to expansion in Bacteroides, with a reduction in Bifidobacterium and Lactobacillus, as in the group deployed without doxycycline. Doxycycline did not alter the community structure and was specifically associated with a reduction in Escherichia and expression of Rothia. Differences in the microbiota existed at baseline between military units but not within the studied groups. This group-effect highlighted the risk of a Simpson paradox in microbiome studies.

The Underlying Effects of Celiac Disease and Subsequent Implications on Deployment in the United States Army

INTRODUCTION

The purpose of this review is to provide an overview of the etiology, pathology, and treatments for celiac disease (CD), as well as to provide context as to how CD impacts the U.S. military.

MATERIALS AND METHODS

To conduct this review, the authors surveyed recent epidemiology and immunology literature in order to provide a detailed summary of the current understanding of CD, its diagnosis, and the real-world impacts within the Department of Defense (DoD).

RESULTS

We described the gluten proteins and both the immune response in CD. We further describe the underlying genetic risk factors and diagnosis and pathogenesis of the disease and conclude the review with a discussion of how current DoD regulations impact U.S. military readiness.

CONCLUSION

Celiac disease (CD) is an autoimmune disorder that results in damage to the small intestine. Ingestion of gluten in a CD patient is usually followed by villous atrophy in the small intestine, often along with other gastrointestinal symptoms. Around 1% of patients diagnosed with CD can experience complications if gluten-free diet is not followed, including intestinal lymphoma and hyposplenism. Therefore, a patient showing possible symptoms should discuss the diagnostic process with their healthcare providers to ensure adequate understanding of serological and genetic tests along with the histological examination of intestinal biopsy. Patients should seek consults with registered dietitians to structure their diets appropriately. Considering the prevalence and incidence of CD and gluten intolerances are increasing, the military should consider providing gluten-free Meals Ready-to-Eat as an option for all service members. Given the retention of service members with CD, subsequent admission of personnel with mild CD that does not affect the duties will allow the DoD access to a growing population of fully capable service members with critical technical skills who are eager to serve the USA.

Sensitivity and reliability of zinc transporter and metallothionein gene expression in peripheral blood mononuclear cells as indicators of zinc status: responses to ex vivo zinc exposure and habitual zinc intake in humans

Zn is an essential nutrient for humans; however, a sensitive biomarker to assess Zn status has not been identified. The objective of this study was to determine the reliability and sensitivity of Zn transporter and metallothionein (MT) genes in peripheral blood mononuclear cells (PBMCs) to Zn exposure ex vivo and to habitual Zn intake in human subjects. In study 1, human PBMCs were cultured for 24 h with 0-50 µm ZnSO4 with or without 5 µm N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and mRNA expression of SLC30A1-10, SLC39A1-14, MT1 subtypes (A, B, E, F, G, H, L, M and X), MT2A, MT3 and MT4 mRNA was determined. In study 2, fifty-four healthy male and female volunteers (31·9 (sd 13·8) years, BMI 25·7 (sd 2·9) kg/m2) completed a FFQ, blood was collected, PBMCs were isolated and mRNA expression of selected Zn transporters and MT isoforms was determined. Study 1: MT1E, MT1F, MT1G, MT1H, MT1L, MT1M, MT1X, MT2A and SLC30A1 increased with increasing concentrations of Zn and declined with the addition of TPEN. Study 2: Average daily Zn intake was 16·0 (sd 5·3) mg/d (range: 9-31 mg/d), and plasma Zn concentrations were 15·5 (SD 2·8) μmol/l (range 11-23 μmol/l). PBMC MT2A was positively correlated with dietary Zn intake (r 0·306, P = 0·03) and total Zn intake (r 0·382, P < 0·01), whereas plasma Zn was not (P > 0·05 for both). Findings suggest that MT2A mRNA in PBMCs reflects dietary Zn intake in healthy adults and may be a component in determining Zn status.

Meeting report of the third annual Tri-Service Microbiome Consortium symposium

The Tri-Service Microbiome Consortium (TSMC) was founded to enhance collaboration, coordination, and communication of microbiome research among U.S. Department of Defense (DoD) organizations and to facilitate resource, material and information sharing among consortium members. The 2019 annual symposium was held 22-24 October 2019 at Wright-Patterson Air Force Base in Dayton, OH. Presentations and discussions centered on microbiome-related topics within five broad thematic areas: 1) human microbiomes; 2) transitioning products into Warfighter solutions; 3) environmental microbiomes; 4) engineering microbiomes; and 5) microbiome simulation and characterization. Collectively, the symposium provided an update on the scope of current DoD microbiome research efforts, highlighted innovative research being done in academia and industry that can be leveraged by the DoD, and fostered collaborative opportunities. This report summarizes the presentations and outcomes of the 3rd annual TSMC symposium.