Targeting the Gut Microbiota to Improve Dietary Protein Efficacy to Mitigate Sarcopenia

Analysis of alterations in the composition of the intestinal microbiota in frail older individuals

BACKGROUND

Frailty is an ageing-associated geriatric syndrome that severely affects the functional status, quality of life and life expectancy of older adults. Immune dysfunction and chronic inflammation play crucial roles in frailty, and this study aimed to explore the correlation between the intestinal microbiota and frailty.

METHODS

A cross-sectional survey was conducted using a comprehensive geriatric assessment of older individuals who underwent medical checkups at the Health Management Center from April 2023 to May 2024. A total of 672 older individuals who met the inclusion criteria were included and divided into a healthy control group and a frail case group. Clinical data, as well as blood and stool samples, were collected. The data from the two groups were analysed with 16S rRNA sequencing in 20 and 30 cases, respectively. SPSS 25.0 was used for statistical analysis.

RESULTS

There were significant differences in income, smoking, and globulin levels between the two groups, while there were no differences in age or sex. There was no significant difference in the abundance or species evenness of intestinal bacteria between the two groups. However, the abundance of accessory bacteria, bifidobacteria, and Escherichia coli in the frail group was greater than that in the control group. Specifically, Escherichia-Shigella was significantly upregulated and fit well into the prediction model of frailty.

CONCLUSION

The gut microbiota of frail older individuals underwent significant changes in structural composition, and the presence of Escherichia-Shigella may be a diagnostic marker for debilitating diseases. These findings provide an essential clinical reference value for developing methods for preventing or alleviating frailty based on specific microbial communities.

Comparison of the gut microbiota in older people with and without sarcopenia: a systematic review and meta-analysis

Introduction

Sarcopenia, an age-related disorder marked by decreased skeletal muscle mass, strength, and function, is associated with negative health impacts in individuals and financial burdens on families and society. Studies have suggested that age-related alterations in gut microbiota may contribute to the development of sarcopenia in older people through the gut-muscle axis, thus modulation of gut microbiota may be a promising approach for sarcopenia treatment. However, the characteristic gut microbiota for sarcopenia has not been consistent across studies. Therefore, the aim of this study was to compare the diversity and compositional differences in the gut microbiota of older people with and without sarcopenia, and to identify gut microbiota biomarkers with therapeutic potential for sarcopenia.

Methods

The PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Database were searched studies about the gut microbiota characteristics in older people with sarcopenia. The quality of included articles was assessed by the Newcastle-Ottawa Scale (NOS). Weighted standardized mean differences (SMDs) and 95% confidence intervals (CIs) for α-diversity index were estimated using a random effects model. Qualitative synthesis was conducted for β-diversity and the correlation between gut microbiota and muscle parameters. The relative abundance of the gut microbiota was analyzed quantitatively and qualitatively, respectively.

Results

Pooled estimates showed that α-diversity was significantly lower in older people with sarcopenia (SMD: -0.41, 95% CI: -0.57 to -0.26, I²: 71%, P < 0.00001). The findings of β-diversity varied across included studies. In addition, our study identified gut microbiota showing a potential and negative correlation with sarcopenia, such as Prevotella, Slackia, Agathobacter, Alloprevotella, Prevotella copri, Prevotellaceae sp., Bacteroides coprophilus, Mitsuokella multacida, Bacteroides massiliensis, Bacteroides coprocola Conversely, a potential and positive correlation was observed with opportunistic pathogens like Escherichia-Shigella, Eggerthella, Eggerthella lenta and Collinsella aerofaciens.

Discussion

This study showed that α-diversity is decreased in sarcopenia, probably predominantly due to diminished richness rather than evenness. In addition, although findings of β-diversity varied across included studies, the overall trend toward a decrease in SCFAs-producing bacteria and an increase in conditionally pathogenic bacteria. This study provides new ideas for targeting the gut microbiota for the prevention and treatment of sarcopenia.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/view/CRD42024573090, identifier CRD42024573090.

The Pathology of Intestinal Mucosal Disruption; Implications for Muscle Loss and Physical Dependency from Late Adolescence to Octogenarians

Background and Objectives

A pathological increase in intestinal permeability causes muscle loss and physical decline by inducing systemic inflammation and oxidative stress. However, most relevant studies investigate older adults, and the appropriate data across age spans remain elusive. This study aimed to examine the associations of intestinal permeability with muscle loss and physical decline across a large span of ages. We measured plasma zonulin, a marker of increased intestinal permeability, from adolescents to octogenarians in association with muscle health and gait speed.

Research Methods and Procedures

In this cross-sectional, observational study, we recruited healthy men, including young (age=18-35 years, n=135), middle-aged (age=35-59 years, n=118), and older (age=60-90 years, n=163) adults for evaluating - handgrip strength (HGS), skeletal muscle mass index (SMI), and gait speed. We also measured plasma zonulin, c-reactive proteins (CRP), and 8-isoprostanes using ELISA assays.

Results

Plasma zonulin gradually increased from young and middle-aged to older adults (all p<0.05). Conversely, HGS and gait speed were progressively reduced from young and middle-aged to older adults (all p<0.05). In addition, older adults also exhibited lower SMI than young and middle-aged men (both p<0.05). Plasma zonulin exhibited significant negative correlations with HGS and gait speed and positive correlations with CRP and 8-isoprostanes in middle-aged and older men (all p<0.05). We also found significant areas under the curve for the efficacy of plasma zonulin in diagnosing low HGS (<27kg) and gait speed (0.8 m/s). After adjustment for age, plasma zonulin demonstrated robust negative correlations with HGS and gait speed and positive correlations with CRP and 8-isoprostanes in the cumulative cohort.

Conclusion

Altogether, an increasing intestinal leak from middle age onward contributes to muscle weakness and physical decline. Our data is clinically relevant in understanding and treating physical dependency in middle-aged and older adults.

Therapeutic strategies to modulate gut microbial health: Approaches for sarcopenia management

Sarcopenia is a progressive and generalized loss of skeletal muscle and functions associated with ageing with currently no definitive treatment. Alterations in gut microbial composition have emerged as a significant contributor to the pathophysiology of multiple diseases. Recently, its association with muscle health has pointed to its potential role in mediating sarcopenia. The current review focuses on the association of gut microbiota and mediators of muscle health, connecting the dots between the influence of gut microbiota and their metabolites on biomarkers of sarcopenia. It further delineates the mechanism by which the gut microbiota affects muscle health with progressing age, aiding the formulation of a multi-modal treatment plan involving nutritional supplements and pharmacological interventions along with lifestyle changes compiled in the review. Nutritional supplements containing proteins, vitamin D, omega-3 fatty acids, creatine, curcumin, kefir, and ursolic acid positively impact the gut microbiome. Dietary fibres foster a conducive environment for the growth of beneficial microbes such as Bifidobacterium, Faecalibacterium, Ruminococcus, and Lactobacillus. Probiotics and prebiotics act by protecting against reactive oxygen species (ROS) and inflammatory cytokines. They also increase the production of gut microbiota metabolites like short-chain fatty acids (SCFAs), which aid in improving muscle health. Foods rich in polyphenols are anti-inflammatory and have an antioxidant effect, contributing to a healthier gut. Pharmacological interventions like faecal microbiota transplantation (FMT), non-steroidal anti-inflammatory drugs (NSAIDs), ghrelin mimetics, angiotensin-converting enzyme inhibitors (ACEIs), and butyrate precursors lead to the production of anti-inflammatory fatty acids and regulate appetite, gut motility, and microbial impact on gut health. Further research is warranted to deepen our understanding of the interaction between gut microbiota and muscle health for developing therapeutic strategies for ameliorating sarcopenic muscle loss.

Exploring the Relationship Between Gut Microbiota and Sarcopenia Based on Gut-Muscle Axis

Sarcopenia, as a disease characterized by progressive decline of quality, strength, and function of muscles, has posed an increasingly significant threat to the health of middle-aged and elderly individuals in recent years. With the continuous deepening of studies, the concept of gut-muscle axis has attracted widespread attention worldwide, and the occurrence and development of sarcopenia are believed to be closely related to the composition and functional alterations of gut microbiota. In this review, combined with existing literatures and clinical reports, we have summarized the role and impacts of gut microbiota on the muscle, the relevance between gut microbiota and sarcopenia, potential mechanisms of gut microbiota in the modulation of sarcopenia, potential methods to alleviate sarcopenia by modulating gut microbiota, and relevant advances and perspectives, thus contributing to adding more novel knowledge to this research direction and providing certain reference for future related studies.

Influence of human gut microbiome on the healthy and the neurodegenerative aging

The gut microbiome plays a crucial role in host health throughout the lifespan by influencing brain function during aging. The microbial diversity of the human gut microbiome decreases during the aging process and, as a consequence, several mechanisms increase, such as oxidative stress, mitochondrial dysfunction, inflammatory response, and microbial gut dysbiosis. Moreover, evidence indicates that aging and neurodegeneration are closely related; consequently, the gut microbiome may serve as a novel marker of lifespan in the elderly. In this narrative study, we investigated how the changes in the composition of the gut microbiome that occur in aging influence to various neuropathological disorders, such as mild cognitive impairment (MCI), dementia, Alzheimer's disease (AD), and Parkinson's disease (PD); and which are the possible mechanisms that govern the relationship between the gut microbiome and cognitive impairment. In addition, several studies suggest that the gut microbiome may be a potential novel target to improve hallmarks of brain aging and to promote healthy cognition; therefore, current and future therapeutic interventions have been also reviewed.

Impact of Gut Microbiota on Aging and Frailty: A Narrative Review of the Literature

Aging is a natural, complex, and individual process that focuses on the progressive decay of the body and a decrease in cell function that begins in approximately the sixth decade of life and ends with death. Current scientific evidence shows that the aging process is mostly related to genetic load and varies because of the environment. Therefore, aging can be adjusted through the intervention of factors that control homeostasis in genetic, biochemical, and immunological processes, including those involving the gut microbiota. Indeed, the diversity of the gut microbiota decreases during aging, based on the presence of modifications in the hormonal, immunological, and operational processes of the gastrointestinal tract. These modifications lead to a state of dysbiosis. However, altering bacterial communities remains complicated due to the great diversity of factors that influence their modification. Alterations caused by the aging process are known to foster dysbiosis and correspond to conditions that determine the degree of frailty in senior citizens. Consequently, the microbial structure can be used as a biomarker for geriatric care in the promotion of healthy aging.

Harnessing immunomodulation to combat sarcopenia: current insights and possible approaches

Sarcopenia is a complex age-associated syndrome of progressive loss of muscle mass and strength. Although this condition is influenced by many factors, age-related changes in immune function including immune cell dynamics, and chronic inflammation contribute to its progression. The complex interplay between the immune system, gut-muscle axis, and autophagy further underscores their important roles in sarcopenia pathogenesis. Immunomodulation has emerged as a promising strategy to counteract sarcopenia. Traditional management approaches to treat sarcopenia including physical exercise and nutritional supplementation, and the emerging technologies of biophysical stimulation demonstrated the importance of immunomodulation and regulation of macrophages and T cells and reduction of chronic inflammation. Treatments to alleviate low-grade inflammation in older adults by modulating gut microbial composition and diversity further combat sarcopenia. Furthermore, some pharmacological interventions, nano-medicine, and cell therapies targeting muscle, gut microbiota, or autophagy present additional avenues for immunomodulation in sarcopenia. This narrative review explores the immunological underpinnings of sarcopenia, elucidating the relationship between the immune system and muscle during ageing. Additionally, the review discusses new areas such as the gut-muscle axis and autophagy, which bridge immune system function and muscle health. Insights into current and potential approaches for sarcopenia management through modulation of the immune system are provided, along with suggestions for future research directions and therapeutic strategies. We aim to guide further investigation into clinical immunological biomarkers and identify indicators for sarcopenia diagnosis and potential treatment targets to combat this condition. We also aim to draw attention to the importance of considering immunomodulation in the clinical management of sarcopenia.

Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial

Studies suggest that inducing gut microbiota changes may alter both muscle physiology and cognitive behaviour. Gut microbiota may play a role in both anabolic resistance of older muscle, and cognition. In this placebo controlled double blinded randomised controlled trial of 36 twin pairs (72 individuals), aged ≥60, each twin pair are block randomised to receive either placebo or prebiotic daily for 12 weeks. Resistance exercise and branched chain amino acid (BCAA) supplementation is prescribed to all participants. Outcomes are physical function and cognition. The trial is carried out remotely using video visits, online questionnaires and cognitive testing, and posting of equipment and biological samples. The prebiotic supplement is well tolerated and results in a changed gut microbiome [e.g., increased relative Bifidobacterium abundance]. There is no significant difference between prebiotic and placebo for the primary outcome of chair rise time (β = 0.579; 95% CI -1.080-2.239 p = 0.494). The prebiotic improves cognition (factor score versus placebo (β = -0.482; 95% CI,-0.813, -0.141; p = 0.014)). Our results demonstrate that cheap and readily available gut microbiome interventions may improve cognition in our ageing population. We illustrate the feasibility of remotely delivered trials for older people, which could reduce under-representation of older people in clinical trials. ClinicalTrials.gov registration: NCT04309292.

Probiotics supplementation or probiotic-fortified products on sarcopenic indices in older adults: systematic review and meta-analysis from recent randomized controlled trials

Introduction: A noteworthy correlation was seen between changes in the gut microbiome and sarcopenia in older adults. Along with increasing research on probiotic supplementation for various medical problems, we aimed to obtain evidence and summarize the effect of probiotic supplementation on sarcopenic indices among older adults. Methods: We utilized PubMed, EBSCO, and Proquest, in addition to manual search using synonyms and variation for 'probiotic,' 'sarcopenia,' and 'older adults.' Randomized controlled trials investigated the utilization of probiotics or probiotic-containing products in older adults with sarcopenic indices including muscle mass and strength. The random-effects model was applied to the meta-analysis process. Results: Seven studies were obtained with 733 pooled older adults. Probiotic supplementation resulted in a significant increase of muscle mass with adjusted SMD (Standardized Mean Difference) of 0.962 (95% CI: 0.288 to 1.635, p = 0.049) using till and trim analysis and muscle strength with SMD of 1.037 (95% CI: 0.077 to 1.996, p = 0.03). However, both outcomes were associated with significantly high heterogeneity (I2 = 89.5% and I2 = 89.9%, respectively). Conclusion: When opposed to a placebo, the probiotic treatment improved the amount of muscle and its endurance based on recent evidence, however, further studies should be done with larger samples and targeted populations.

Probiotic BC30 Improves Amino Acid Absorption from Plant Protein Concentrate in Older Women

Weizmannia coagulans GBI-30, 6086 (BC30) has previously been shown to increase protein digestion in an in vitro model of the stomach and small intestine and amino acid appearance in healthy men and women after ingestion of milk protein concentrate. The impact of ingesting BC30 with other protein sources or in other demographics is largely unknown. The purpose of this study was to examine the impact of adding BC30 to a 20-g dose of a blend of rice and pea protein on postprandial changes in blood amino acids concentrations in healthy, older women. Healthy, older females (n = 30, 58.5 ± 5.2 years, 165.4 ± 6.8 cm, 65.6 ± 8.8 kg, 23.7 ± 3.2 kg/m2) completed two separate 14-day supplementation protocols separated by a 3-week washout period. Participants were instructed to ingest a 20-g protein dose of a blend of rice and pea protein concentrates (ProDiem Plant Protein Solutions, Kerry) with (PPCBC30) or without (PPC) the addition of 1 × 109 CFU BC30 (Kerry). Body composition and demographics were assessed upon arrival to the laboratory. Upon ingestion of their final assigned supplemental dose, blood samples were taken at 0 (baseline), 30-, 60-, 90-, 120-, 180-, and 240-min post-consumption and analyzed for amino acid concentrations. Alanine (p = 0.018), tryptophan (p = 0.003), cysteine (p = 0.041), essential amino acids (p = 0.050), and total amino acids (p = 0.039) all exhibited significantly (p ≤ 0.05) greater AUC with PPCBC30 when compared to PPC. In addition, tryptophan (p = 0.003), cysteine (p = 0.021), essential amino acids (p = 0.049), and total amino acids (p = 0.035) displayed significantly greater (p ≤ 0.05) concentration maximum (CMax) values in PPCBC30 when compared to PPC. Finally, time to reach CMax (TMax) was similar between conditions with 80% of all measured amino acids and amino acid combinations achieving CMax at a similar time (~ 60 min). Only phenylalanine TMax was found to be different (p = 0.01) between the two conditions with PPC displaying a greater proportion of TMax values after 30 min. Following qualitative (non-inferential) assessment, 88% of all measured outcomes achieved a higher AUC with PPCBC30 and 100% of all outcomes achieved a higher CMax with PPCBC30. In concert with previous findings in a younger mixed gender cohort with milk protein, the addition of BC30 to a daily 20-g dose of plant protein concentrate in healthy older women improved AUC and CMax values in several individual amino acids and amino acid combinations. Retrospectively registered on April 6, 2022, at ClinicalTrials.gov as NCT05313178.

Effect of Cucumis melo L. peel extract supplemented postbiotics on reprograming gut microbiota and sarcopenia in hindlimb-immobilized mice

Postbiotics made from lactic acid bacteria may ameliorate sarcopenia via the metabolic reprogramming of gut dysbiosis. This study investigated the anti-sarcopenic effect of postbiotics (WDK) produced from polyphenol-rich melon peel extract (Cucumis melo L. var. makuwa, KEE) and whey with Lentilactobacillus kefiri DH5 (DH5) in C2C12 skeletal muscle cells and hindlimb-immobilized mice. WDK significantly ameliorated palmitate-induced atrophy of C2C12 cells, restoring myotube length and diameter. It also upregulated the expression of myogenic genes including Atrogin-1, Igf-1, and MyoD. Hindlimb-immobilized C57BL/6J mice were randomly divided and orally administered 10 mL/kg body weight of saline (CON), Whey, Whey + DH5 (WD), DH5 + KEE, Whey + DH5 + KEE postbiotic (WDK) for three weeks (n = 10/group). Interestingly, WDK significantly improved muscle function in hindlimb-immobilized mice by restoring both the grip strength and the mass of the soleus muscle, which was closely related to the upregulation of the myoD gene. WDK increased microbial diversity and modulated the distribution of intestinal bacteria, particularly those involved in protein synthesis and the production of butyrate. There was a significant correlation between myogenic biomarkers and butyrate producing gut microbiota. Restoration of muscle mass and function following postbiotic WDK is strongly related to the regulation of myogenic genes by in part remodulating gut microbiota. In conclusion, these findings suggest that polyphenol- and whey-based postbiotics WDK may have potential as an effective manner to combat the progression of sarcopenia.

Nutritional Value of Yogurt as a Protein Source: Digestibility/Absorbability and Effects on Skeletal Muscle

Yogurt is a traditional fermented food that is accepted worldwide for its high palatability and various health values. The milk protein contained in yogurt exhibits different physical and biological properties from those of non-fermented milk protein due to the fermentation and manufacturing processes. These differences are suggested to affect the time it takes to digest and absorb milk protein, which in turn will influence the blood levels of amino acids and/or hormones, such as insulin, and thereby, the rate of skeletal muscle protein synthesis via the activation of intracellular signaling, such as the mTORC1 pathway. In addition, based on the relationship between gut microbiota and skeletal muscle conditions, yogurt, including lactic acid bacteria and its metabolites, has been evaluated for its role as a protein source. However, the substantial value of yogurt as a protein source and the additional health benefits on skeletal muscle are not fully understood. The purpose of this review is to summarize the research to date on the digestion and absorption characteristics of yogurt protein, its effect on skeletal muscle, and the contribution of lactic acid bacterial fermentation to these effects.

Exploring the Relationship between the Gut Microbiota and Ageing: A Possible Age Modulator

The gut microbiota (GM) has been the subject of intense research in recent years. Therefore, numerous factors affecting its composition have been thoroughly examined, and with them, their function and role in the individual's systems. The gut microbiota's taxonomical composition dramatically impacts older adults' health status. In this regard, it could either extend their life expectancy via the modulation of metabolic processes and the immune system or, in the case of dysbiosis, predispose them to age-related diseases, including bowel inflammatory and musculoskeletal diseases and metabolic and neurological disorders. In general, the microbiome of the elderly tends to present taxonomic and functional changes, which can function as a target to modulate the microbiota and improve the health of this population. The GM of centenarians is unique, with the faculty-promoting metabolic pathways capable of preventing and counteracting the different processes associated with age-related diseases. The molecular mechanisms by which the microbiota can exhibit anti-ageing properties are mainly based on anti-inflammatory and antioxidant actions. This review focuses on analysing the current knowledge of gut microbiota characteristics and modifiers, its relationship with ageing, and the GM-modulating approaches to increase life expectancy.

An innovative food system approach to diversifying protein intake: Protein-I: Shared Island sustainable healthy nutrition

There is a need to transform our current food system if we are to feed the rapidly expanding global population while maintaining planetary health. Within the island of Ireland, there is an urgent need to diversify the foods that currently contribute to our populations' protein intake. A Shared Island Innovative Food System approach is required to achieve this in a manner that is sustainable and provides benefits to producers, consumers and other supply chain participants. The Protein-I project employs such an approach, with the paradigm focusing on production of plant food through to human health, while paying particular attention to the development of the rural bioeconomy. Using an interdisciplinary approach, the team will develop strategies to maximise sustainable plant protein production in a traceable/transparent fashion and assess the impact of changes to existing value chains and the development of new value chains for the rural economy. A smart supply chain technology solution tailored to the needs of the agri-food industry will be developed and tested. Additionally, we will co-design consumer-led approaches to diversify plant protein intake, model the impact of changes at the population level and perform human interventions to demonstrate efficacy in terms of achieving adequate nutrition and improved health. Comprehensive engagement with stakeholders is embedded throughout the whole project to embrace the multi-actor approach. Overall, the project will be a key step towards future-proofing our food system on the island of Ireland and moving towards protecting planetary and population health, within the context of a just transition.

Targeting the gut to prevent and counteract metabolic disorders and pathologies during aging

Impairment of gut function is one of the explanatory mechanisms of health status decline in elderly population. These impairments involve a decline in gut digestive physiology, metabolism and immune status, and associated to that, changes in composition and function of the microbiota it harbors. Continuous deteriorations are generally associated with the development of systemic dysregulations and ultimately pathologies that can worsen the initial health status of individuals. All these alterations observed at the gut level can then constitute a wide range of potential targets for development of nutritional strategies that can impact gut tissue or associated microbiota pattern. This can be key, in a preventive manner, to limit gut functionality decline, or in a curative way to help maintaining optimum nutrients bioavailability in a context on increased requirements, as frequently observed in pathological situations. The aim of this review is to give an overview on the alterations that can occur in the gut during aging and lead to the development of altered function in other tissues and organs, ultimately leading to the development of pathologies. Subsequently is discussed how nutritional strategies that target gut tissue and gut microbiota can help to avoid or delay the occurrence of aging-related pathologies.

Low Protein Diet Improves Meat Quality and Modulates the Composition of Gut Microbiota in Finishing Pigs

This study investigated the effect of a low protein (LP) diet on growth performance, nitrogen emission, carcass traits, meat quality, and gut microbiota in finishing pigs. Fifty-four barrows (Duroc × Landrace × Yorkshire) were randomly assigned to three treatments with six replicates (pens) of three pigs each. The pigs were fed with either high protein (HP, 16% CP), medium protein (MP, 12% CP), and LP diets (10% CP), respectively. The LP diets did not influence the growth performance, but significantly decreased the plasma urea nitrogen contents and fecal nitrogen emission (P < 0.05). The LP diet significantly decreased the plasma contents of malondialdehyde (MDA) and increased the plasma glutathione (GSH) contents (P < 0.05). The LP diets significantly increased the backfat thickness at the first and last ribs, L^* (lightness) value of meat color, and muscle fiber density in the longissimus dorsi (P < 0.05). The messenger RNA (mRNA) expression of fatty acid synthetase (FAS), peroxisome proliferator-activated receptor-gamma (PPARγ), leptin, and acetyl-CoA carboxylase (ACC) was significantly downregulated, while that of carnitine palmitoyltransferase 1 (CPT1) and myosin heavy chain (MYHC) IIx in the longissimus Dorsi muscle was significantly upregulated by LP diets (P < 0.05). The 16S sequencing analysis showed that the abundance of unidentified Bacteria at the phylum level, and Halanaerobium and Butyricicoccusat at the genus level in the colonic digesta were significantly decreased by LP diet (P < 0.05). The LP diet significantly decreased the observed species of α-diversity in both ileal and colonic microbiota (P < 0.05). Spearman correlation analysis identified a significant positive correlation between the abundance of the ileal genera Streptococcus and L^* value at 24 and 48 h, and a significant negative correlation between unidentified_Ruminococcasceae in both ileum and colon with L^* value at 24 h (P < 0.05). Collectively, the LP diet supplemented with lysine, methionine, threonine, and tryptophan could reduce the fecal nitrogen emission without affecting growth performance and improve meat quality by regulating the antioxidant capacity and gene expression involved in fat metabolism as well as modulating the gut microbiota composition in finishing pigs.

Rice bran protein oxidation induced by rancidity alters the gut microbiota and intestinal permeability in mice

Dietary protein is crucial for maintaining body growth and plays a significant role in shaping the gut microbiota. Rice bran (RB) rancidity can induce rice bran protein (RBP) oxidation and change the structural characteristics, which further impacts the functional properties and nutritional value of RBP. Therefore, the impact of rancidity-induced RBP oxidation on the gut microbiota and intestinal permeability was evaluated. Oxidized RBP significantly altered the α-diversity of the gut microbiota and impacted the microbial profile at phylum and genus levels, and moderately oxidized RBP caused increasing abundance of Akkermansia and reducing abundance of Desulfovibrio. Different oxidation extents of RBP induced different biomarkers, indicating that the composition of the gut microbiota presented an oxidation extent-dependent pattern. Oxidized RBP also significantly promoted the level of formic acid and reduced the level of isovaleric acid. Moreover, oxidized RBP significantly upregulated the expression of genes related to tight junction proteins. The phenomena indicated that oxidized RBP significantly changed the composition of the gut microbiota and improved the barrier function of the intestine, while showing fewer effects on the production of short-chain fatty acids (SCFAs). The research provides a theoretical reference for understanding the effects of plant protein oxidation on intestinal health during food storage and processing.

Radiotherapy-Induced Digestive Injury: Diagnosis, Treatment and Mechanisms

Radiotherapy is one of the main therapeutic methods for treating cancer. The digestive system consists of the gastrointestinal tract and the accessory organs of digestion (the tongue, salivary glands, pancreas, liver and gallbladder). The digestive system is easily impaired during radiotherapy, especially in thoracic and abdominal radiotherapy. In this review, we introduce the physical classification, basic pathogenesis, clinical characteristics, predictive/diagnostic factors, and possible treatment targets of radiotherapy-induced digestive injury. Radiotherapy-induced digestive injury complies with the dose-volume effect and has a radiation-based organ correlation. Computed tomography (CT), MRI (magnetic resonance imaging), ultrasound (US) and endoscopy can help diagnose and evaluate the radiation-induced lesion level. The latest treatment approaches include improvement in radiotherapy (such as shielding, hydrogel spacers and dose distribution), stem cell transplantation and drug administration. Gut microbiota modulation may become a novel approach to relieving radiogenic gastrointestinal syndrome. Finally, we summarized the possible mechanisms involved in treatment, but they remain varied. Radionuclide-labeled targeting molecules (RLTMs) are promising for more precise radiotherapy. These advances contribute to our understanding of the assessment and treatment of radiation-induced digestive injury.