Independent and Interactive Effects of Habitually Ingesting Fermented Milk Products Containing Lactobacillus casei Strain Shirota and of Engaging in Moderate Habitual Daily Physical Activity on the Intestinal Health of Older People

Associations between gut microbiota and sarcopenia or its defining parameters in older adults: A systematic review

Altered gut microbiota (GM) potentially contribute to development or worsening of sarcopenia through a gut-muscle axis. This systematic review aims to compare GM between persons with sarcopenia or low sarcopenia-defining parameters (muscle mass, strength, and physical performance) to those with preserved muscle status, as well as to clarify possible associations between sarcopenia (-defining parameters) and relative abundance (RA) of GM-taxa or GM-(α- or β) diversity indices, in order to clarify whether there is robust evidence of the existence of a GM signature for sarcopenia. This systematic review was conducted according to the PRISMA-reporting guideline and pre-registered on PROSPERO (CRD42021259597). PubMed, Web of Science, Embase, ClinicalTrials.gov, and Cochrane library were searched until 20 July 2023. Included studies reported on GM and sarcopenia or its defining parameters. Observational studies were included with populations of mean age ≥50 years. Thirty-two studies totalling 10 781 persons (58.56% ♀) were included. Thirteen studies defined sarcopenia as a construct. Nineteen studies reported at least one sarcopenia-defining parameter (muscle mass, strength or physical performance). Studies found different GM-taxa at multiple levels to be significantly associated with sarcopenia (n = 4/6), muscle mass (n = 13/14), strength (n = 7/9), and physical performance (n = 3/3); however, directions of associations were heterogeneous and also conflicting for specific GM-taxa. Regarding β-diversity, studies found GM of persons with sarcopenia, low muscle mass, or low strength to cluster differently compared with persons with preserved muscle status. α-diversity was low in persons with sarcopenia or low muscle mass as compared with those with preserved muscle status, indicating low richness and diversity. In line with this, α-diversity was significantly and positively associated with muscle mass (n = 3/4) and muscle strength (n = 2/3). All reported results were significant (P < 0.05). Persons with sarcopenia and low muscle parameters have less rich and diverse GM and can be separated from persons with preserved muscle mass and function based on GM-composition. Sarcopenia and low muscle parameters are also associated with different GM-taxa at multiple levels, but results were heterogeneous and no causal conclusions could be made due to the cross-sectional design of the studies. This emphasizes the need for uniformly designed cross-sectional and longitudinal trials with appropriate GM confounder control in large samples of persons with sarcopenia and clearly defined core outcome sets in order to further explore changes in GM-taxa and to determine a sarcopenia-specific GM-signature.

The antioxidant activity and metabolomic analysis of the supernatant of Streptococcus alactolyticus strain FGM

Strain-specific probiotics can present antioxidant activity and reduce damage caused by oxidation. Streptococcus alactolyticus strain FGM (S. alactolyticus strain FGM) isolated from the chicken cecum shows potential probiotic properties which have been previously demonstrated. However, the antioxidant properties of S. alactolyticus strain FGM remain unknown. In this view, cell-free supernatant (CFS), intact cells (IC) and intracellular extracts (CFE) of strain FGM and 3 strains of Lactobacillus (LAB) were prepared, and their scavenging capacities against DPPH, hydroxyl radicals and linoleic acid peroxidation inhibitory were compared in this study. The effects of strain FGM cell-free supernatant (FCFS) on NO production, activity of SOD and GSH-Px in RAW264.7 cells and LPS-induced RAW264.7 cells were analyzed. The metabolites in the supernatant were quantitated by N300 Quantitative Metabolome. It was shown that the physicochemical characteristics of CFS to scavenge DPPH, hydroxyl radicals, and linoleic acid peroxidation inhibitory were significantly stronger than that of IC and CFE in the strain FGM (P < 0.05), respectively 87.12% ± 1.62, 45.03% ± 1.27, 15.63% ± 1.34. FCFS had a promotional effect on RAW264.7 cells, and significantly elevated SOD and GSH-Px activities in RAW264.7 cells. 25 μL FCFS significantly promoted the proliferation of RAW264.7 cells induced by LPS, increased the activities of SOD and GSH-PX, and decreased the release of NO. Furthermore, among the differential metabolites of FCFS quantified by N300, 12 metabolites were significantly up-regulated, including lactic acid, indole lactic acid, linoleic acid, pyruvic acid etc., many of which are known with antioxidant properties. In conclusion, FCFS had good antioxidant properties and activity, which can be attributed to metabolites produced from strain FGM fermentation. It was further confirmed that S. alactolyticus strain FGM and its postbiotic have potential probiotic properties and bright application prospects in livestock and poultry breeding.

The oral administration of Lacticaseibacillus casei Shirota alleviates acetaminophen-induced liver injury through accelerated acetaminophen metabolism via the liver-gut axis in mice

Acetaminophen is a widely used antipyretic and analgesic drug, and its overdose is the leading cause of drug-induced acute liver failure. This study aimed to investigate the effect and mechanism of Lacticaseibacillus casei Shirota (LcS), an extensively used and highly studied probiotic, on acetaminophen-induced acute liver injury. C57BL/6 mice were gavaged with LcS suspension or saline once daily for 7 days before acute liver injury was induced via intraperitoneal injection of 300 mg/kg acetaminophen. The results showed that LcS significantly decreased acetaminophen-induced liver and ileum injury, as demonstrated by reductions in the increases in aspartate aminotransferase, total bile acids, total bilirubin, indirect bilirubin, and hepatic cell necrosis. Moreover, LcS alleviated acetaminophen-induced intestinal mucosal permeability, decreased serum IL-1α and lipopolysaccharide levels, and elevated serum eosinophil chemokine (eotaxin) and hepatic glutathione levels. Furthermore, analysis of the gut microbiota and metabolome showed that LcS reduced the acetaminophen-enriched levels of Cyanobacteria, Oxyphotobacteria, long-chain fatty acids, cholesterol, and sugars in the gut. Additionally, the transcriptomic and proteomic results showed that LcS mitigated the decrease in metabolic and immune pathways as well as glutathione formation during acetaminophen-induced acute liver injury. This is the first study showing that pretreatment with LcS alleviates acetaminophen-enriched acute liver injury, and it provides a reference for the application of LcS.IMPORTANCEAcetaminophen is the most frequently used antipyretic analgesic worldwide. As a result, overdoses easily occur and lead to drug-induced acute liver injury, which quickly progresses to liver failure with a mortality of 60%-80% if not corrected in time. The current emergency treatment for overused acetaminophen needs to be administered within 8 hours to avoid liver injury or even liver failure. Therefore, developing preventive strategies for liver injury during planned acetaminophen medication is particularly important, preferably nonpharmacological methods. Lacticaseibacillus casei Shirota (LcS) is a famous probiotic that has been used for many years. Our study found that LcS significantly alleviated acetaminophen-induced acute liver injury, especially acetaminophen-induced liver injury toward fulminant hepatic failure. Here, we elucidated the function and potential mechanisms of LcS in alleviating acetaminophen-induced acute liver injury, hoping it will provide preventive strategies to people during acetaminophen treatment.

Characterization of gut microbiota in mouse models of aging and sarcopenia

Gut microbiota play vital roles in the maintenance of human health and in various diseases. We aimed to investigate the association of gut microbiota with aging and sarcopenia. This study contained two experimental designs using the ICR mouse model for 1) determining the association between aging and gut microbiota (by analyzing murine fecal samples) and 2) determining the association between sarcopenia and gut microbiota in mice treated with microorganisms or dexamethasone. The composition of the gut microbiota was determined by next-generation sequencing. Marginally significant differences were observed in taxon composition of the gut microbiota depending on age; particularly, the abundance of the genusAlistipes increased with increasing age. In addition, the abundance of the class Bacteroidia decreased with increasing age, whereas that of the genus Oscillibacter increased. The microbiome composition differed between young mice and aging mice with sarcopenia. Moreover, the gut microbiota in aging and sarcopenia showed altered abundances of Alistipes, Lachnospiraceae, and Bacteroides. Although the sample size was small, these results point to similarities in the gut microbiota between aging and sarcopenia and to differences between young and old individuals. The results on gut microbiota obtained in this study form a basis for studying the development of sarcopenia in geriatric animal models in the future.

A meta-analysis of the effect of probiotic administration on age-related sarcopenia

Global increase in the prevalence of age-related diseases, such as sarcopenia, highlights the need of recognizing agents that improve muscle health; however, the evidence synthesis on the impact of probiotic administration on sarcopenia is scarce. To summarize and evaluate findings regarding the effect of supplementation with probiotics on sarcopenia, this meta-analysis was conducted. Using databases, including PubMed, SCOPUS, ISI-Web of Science, and Cochrane Library, interventional studies were included if they investigate the effect of probiotic administration on at least one of the components of sarcopenia up to 6 October 2022. Risk of bias evaluation was conducted using the Cochrane quality assessment tool. The random-effects model which takes between-study variations into account was used to obtain the overall effect sizes. The STATA version 14.0 was used for statistical analyses. Overall, 17 studies were included. There was high certainty of evidence that probiotic supplementation has a beneficial effect on muscle mass (kg) (WMD: 0.55, 95% CI: 0.05, 1.05; I 2: 0.0%, p = .995), and muscle function (WMD: 0.13, 95% CI: 0.03, 0.23; I 2: 65.6%, p = .05). Moreover, administration of probiotics for more than 12 weeks significantly increased muscle strength (WMD: 1.16, 95% CI: 0.88, 1.44; I 2: 0.0%, p = .77). However, probiotic supplementation had no effect on anthropometric indices, including body mass index. Probiotic supplementation could improve muscle mass and muscle function in adults more than 55 years old. The beneficial effect of probiotics on muscle strength could appear after 12 weeks of supplementation.

Probiotic potential of Lactobacillus sakei L-7 in regulating gut microbiota and metabolism

A growing body of research suggests that gut microbiota is inextricably linked to host health and disease，so we are committed to finding more probiotic resources that are beneficial to human health. This study evaluated the probiotic properties of Lactobacillus sakei L-7 isolated from home-made sausages. The basic probiotic properties of L. sakei L-7 were evaluated through in vitro tests. The strain showed 89% viability after 7 h of digestion in simulating gastric and intestinal fluid. The hydrophobicity, self-aggregation and co-aggregation of L. sakei L-7 showed it had a strong adhesion ability. C57BL/6 J mice were fed L. sakei L-7 for 4 weeks. 16 S rRNA gene analysis indicated that intake of L. sakei L-7 increased the richness of gut microbiota and abundance of beneficial bacteria Akkermansia, Allobaculum and Parabacteroides. Metabonomics analysis revealed that beneficial metabolite gamma-aminobutyric acid and docosahexaenoic acid increased significantly. While the level of metabolite sphingosine and arachidonic acid significantly decreased. In addition, serum levels of inflammatory cytokines interleukin (IL)- 6 and tumor necrosis factor (TNF)-α were significantly decreased. The results suggested that L. sakei L-7 may promote gut health and reduce the occurrence of inflammatory response, it has the potential to become a probiotic.

Physical Exercise and Diet: Regulation of Gut Microbiota to Prevent and Treat Metabolic Disorders to Maintain Health

Each person's body is host to a large number and variety of gut microbiota, which has been described as the second genome and plays an important role in the body's metabolic process and is closely related to health. It is common knowledge that proper physical activity and the right diet structure can keep us healthy, and in recent years, researchers have found that this boost to health may be related to the gut microbiota. Past studies have reported that physical activity and diet can modulate the compositional structure of the gut microbiota and further influence the production of key metabolites of the gut microbiota, which can be an effective way to improve body metabolism and prevent and treat related metabolic diseases. In this review, we outline the role of physical activity and diet in regulating gut microbiota and the key role that gut microbiota plays in improving metabolic disorders. In addition, we highlight the regulation of gut microbiota through appropriate physical exercise and diet to improve body metabolism and prevent metabolic diseases, aiming to promote public health and provide a new approach to treating such diseases.

Relationships between dietary diversity and gut microbial diversity in the elderly

Diet is considered as a major driver of gut microbiota composition. However, little is known about the relationship between overall dietary balance and gut microbiota, especially in the elderly. Here, using the Quantitative Index for Dietary Diversity (QUANTIDD), we analysed the relationships between dietary diversity and gut microbiota diversity in 445 Japanese subjects aged 65-90 years. We also examined the effect of age by comparing the young-old group aged 65 to 74 years (<75 years group; n=246) and the old-old group aged 75 years and older (≥75 years group; n=199). QUANTIDD showed significant positive relationships with Pielou's evenness and Shannon indices, two α-diversity indices related to the uniformity of species distribution. This suggests that a more diverse diet is associated with a more uniform abundance of various bacterial groups, rather than a greater variety of gut bacteria. QUANTIDD also showed significant positive associations with the abundance of Anaerostipes, Eubacterium eligens group, and Eubacterium ventriosum group, which produce short-chain fatty acids (SCFAs) and are beneficial to health. Negative association was found with the abundance of Ruminococcus gnavus group, which produces inflammatory polysaccharides. Positive associations between QUANTIDD and α-diversity indices or the abundance of specific bacterial groups were identified among all subjects and in the <75 years group, but not in the ≥75 years group. Our results suggest that dietary diversity contributes to the diversity of the gut microbiota and increases the abundance of SCFAs-producing bacteria, but only up to a certain age. These findings help to understand the complex relationship between diet and gut microbiota, and provide hints for specific dietary interventions to promote beneficial gut microbiota in the elderly.

A review of the preclinical and clinical studies on the role of the gut microbiome in aging and neurodegenerative diseases and its modulation

As the world population ages, the burden of age-related health problems grows, creating a greater demand for new novel interventions for healthy aging. Advancing aging is related to a loss of beneficial mutualistic microbes in the gut microbiota caused by extrinsic and intrinsic factors such as diet, sedentary lifestyle, sleep deprivation, circadian rhythms, and oxidative stress, which emerge as essential elements in controlling and prolonging life expectancy of healthy aging. This condition is known as gut dysbiosis, and it affects normal brain function via the brain-gut microbiota (BGM) axis, which is a bidirectional link between the gastrointestinal tract (GIT) and the central nervous system (CNS) that leads to the emergence of brain disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). Here, we reviewed the role of the gut microbiome in aging and neurodegenerative diseases, as well as provided a comprehensive review of recent findings from preclinical and clinical studies to present an up-to-date overview of recent advances in developing strategies to modulate the intestinal microbiome by probiotic administration, dietary intervention, fecal microbiota transplantation (FMT), and physical activity to address the aging process and prevent neurodegenerative diseases. The findings of this review will provide researchers in the fields of aging and the gut microbiome design innovative studies that leverage results from preclinical and clinical studies to better understand the nuances of aging, gut microbiome, and neurodegenerative diseases.

Gut microbiota in sarcopenia and heart failure

Sarcopenia is common in aging and in patients with heart failure (HF) who may experience worse outcomes. Patients with muscle wasting are more likely to experience falls and can have serious complications when undergoing cardiac procedures. While intensive nutritional support and exercise rehabilitation can help reverse some of these changes, they are often under-prescribed in a timely manner, and we have limited insights into who would benefit. Mechanistic links between gut microbial metabolites (GMM) have been identified and may contribute to adverse clinical outcomes in patients with cardio-renal diseases and aging. This review will examine the emerging evidence for the influence of the gut microbiome-derived metabolites and notable signaling pathways involved in both sarcopenia and HF, especially those linked to dietary intake and mitochondrial metabolism. This provides a unique opportunity to gain mechanistic and clinical insights into developing novel therapeutic strategies that target these GMM pathways or through tailored nutritional modulation to prevent progressive muscle wasting in elderly patients with heart failure.

A Guide to Dietary Pattern-Microbiome Data Integration

The human gut microbiome is linked to metabolic and cardiovascular disease risk. Dietary modulation of the human gut microbiome offers an attractive pathway to manipulate the microbiome to prevent microbiome-related disease. However, this promise has not been realized. The complex system of diet and microbiome interactions is poorly understood. Integrating observational human diet and microbiome data can help researchers and clinicians untangle the complex systems of interactions that predict how the microbiome will change in response to foods. The use of dietary patterns to assess diet-microbiome relations holds promise to identify interesting associations and result in findings that can directly translate into actionable dietary intake recommendations and eating plans. In this article, we first highlight the complexity inherent in both dietary and microbiome data and introduce the approaches generally used to explore diet and microbiome simultaneously in observational studies. Second, we review the food group and dietary pattern-microbiome literature focusing on dietary complexity-moving beyond nutrients. Our review identified a substantial and growing body of literature that explores links between the microbiome and dietary patterns. However, there was very little standardization of dietary collection and assessment methods across studies. The 54 studies identified in this review used ≥7 different methods to assess diet. Coupled with the variation in final dietary parameters calculated from dietary data (e.g., dietary indices, dietary patterns, food groups, etc.), few studies with shared methods and assessment techniques were available for comparison. Third, we highlight the similarities between dietary and microbiome data structures and present the possibility that multivariate and compositional methods, developed initially for microbiome data, could have utility when applied to dietary data. Finally, we summarize the current state of the art for diet-microbiome data integration and highlight ways dietary data could be paired with microbiome data in future studies to improve the detection of diet-microbiome signals.

Characteristics of gut microbiome, organic acid profiles and viral antibody indexes of healthy Japanese with live Lacticaseibacillus detected in stool

To estimate the health-promoting effects of Lacticaseibacillus paracasei (previously Lactobacillus casei) strain Shirota (LcS) that reached the lower gastrointestinal tract alive, we investigated the characteristics of gut microbiome, organic acid profiles, defecatory symptoms and serum viral antibody indexes of healthy Japanese adults between the group in whom live LcS was detected or not from stool. The β-diversity index of the gut microbiome constituted a significant difference between the live-LcS-detected-group (LLD) and the live-LcS-not-detected-group (LLnD). In the LLD, the Bifidobacteriaceae, Lactobacillaceae, and Coriobacteriaceae counts were significantly higher, and the succinate concentration was significantly lower than that in the LLnD. The serum herpes simplex virus (HSV) immunoglobulin (Ig)M antibody index in the LLD tended to be lower than that of the LLnD in HSV IgG-positive subjects. Of the LLD, those in the fermented milk products containing LcS (FML)-high-frequency-group (FML-HF) and those in the FML-low-frequency-group (FML-LF) had different gut microbiome and organic acid profiles. However, the pattern of differences between FML-HF and FML-LF was dissimilar those between LLD and LLnD. In contrast, among subjects with FML-LF, those in the group with LLD in stool (LF-LLD) and those in the LLnD in stool (LF-LLnD) showed a similar pattern of differences in their gut microbiome and organic acid profiles as those in the LLnD and LLD. The LLD and LF-LLD commonly had lower caloric and carbohydrate intakes from the diet than their respective control groups. In this study, we found that the presence of live LcS in stool is associated with a healthy gut environment and inhibition of the reactivation of latently infected viruses in the host. However, these health-promoting effects on the host were not related to the frequency of FML intake. Furthermore, dysbiosis of the gut microbiome and diet including caloric intake was related to the viability of ingested LcS in the gut.

The Clash of Microbiomes: From the Food Matrix to the Host Gut

Food fermentation has led to the improvement of the safety characteristics of raw materials and the production of new foodstuffs with elevated organoleptic characteristics. The empirical observation that these products could have a potential health benefit has garnered the attention of the scientific community. Therefore, several studies have been conducted in animal and human hosts to decipher which of these products may have a beneficial outcome against specific ailments. However, despite the accumulating literature, a relatively small number of products have been authorized as ‘functional foods’ by regulatory bodies. Data inconsistency and lack of in-depth preclinical characterization of functional products could heavily contribute to this issue. Today, the increased availability of omics platforms and bioinformatic algorithms for comprehensive data analysis can aid in the systematic characterization of microbe–microbe, microbe–matrix, and microbe–host interactions, providing useful insights about the maximization of their beneficial effects. The incorporation of these platforms in food science remains a challenge; however, coordinated efforts and interdisciplinary collaboration could push the field toward the dawn of a new era.

Intake of MPRO3 over 4 Weeks Reduces Glucose Levels and Improves Gastrointestinal Health and Metabolism

Human gut microbiota are involved in different metabolic processes, such as digestion and nutrient synthesis, among others. For the elderly, supplements are a major means of maintaining health and improving intestinal homeostasis. In this study, 51 elderly women were administered MPRO3 (n = 17), a placebo (n = 16), or both (MPRO3: 1 week, placebo: 3 weeks; n = 18) for 4 weeks. The fecal microbiota were analyzed by sequencing the 16S rRNA gene V3–V4 super-variable region. The dietary fiber intake increased, and glucose levels decreased with 4-week MPRO3 intake. Reflux, indigestion, and diarrhea syndromes gradually improved with MPRO3 intake, whereas constipation was maintained. The stool shape also improved. Bifidobacterium animalis, B. pseudolongum, Lactobacillus plantarum, and L. paracasei were relatively more abundant after 4 weeks of MPRO3 intake than in those subjects after a 1-week intake. Bifidobacterium and B. longum abundances increased after 1 week of MPRO3 intake but decreased when the intake was discontinued. Among different modules and pathways, all 10 modules analyzed showed a relatively high association with 4-week MPRO3 intake. The mineral absorption pathway and cortisol biosynthesis and secretion pathways correlated with the B. animalis and B. pseudolongum abundances at 4 weeks. Therefore, 4-week MPRO3 intake decreased the fasting blood glucose level and improved intestinal health and metabolism.

Different Types and Functional Effects of Probiotics on Human Health through Regulating Glucose Homeostasis

With the increasing improvement of people's living standards, hyperglycemia has become one of the most frequent diseases in the world. The current drug therapy may have some negative effects and even cause some complications. As one of the most popular functional ingredients, probiotic bacteria have been proven to play important roles in balancing the glucose homeostasis level in animal and human clinic trials. In this perspective, we sorted three types of probiotics, discussed probiotic safety evaluation, and listed the known probiotic functional foods that assist to control glucose homeostasis. Then, the further summarization of the mechanisms on how probiotic bacteria could regulate glucose homeostasis and the developing trend of probiotic functional foods were discussed.

Understanding the gut microbiota and sarcopenia: a systematic review

BACKGROUND

Gut microbiota dysbiosis and sarcopenia commonly occur in the elderly. Although the concept of the gut-muscle axis has been raised, the casual relationship is still unclear. This systematic review analyses the current evidence of gut microbiota effects on muscle/sarcopenia.

METHODS

A systematic review was performed in PubMed, Embase, Web of Science, and The Cochrane Library databases using the keywords (microbiota* OR microbiome*) AND (sarcopen* OR muscle). Studies reporting the alterations of gut microbiota and muscle/physical performance were analysed.

RESULTS

A total of 26 pre-clinical and 10 clinical studies were included. For animal studies, three revealed age-related changes and relationships between gut microbiota and muscle. Three studies focused on muscle characteristics of germ-free mice. Seventy-five per cent of eight faecal microbiota transplantation studies showed that the recipient mice successfully replicated the muscle phenotype of donors. There were positive effects on muscle from seven probiotics, two prebiotics, and short-chain fatty acids (SCFAs). Ten studies investigated on other dietary supplements, antibiotics, exercise, and food withdrawal that affected both muscle and gut microbiota. Twelve studies explored the potential mechanisms of the gut-muscle axis. For clinical studies, 6 studies recruited 676 elderly people (72.8 ± 5.6 years, 57.8% female), while 4 studies focused on 244 young adults (29.7 ± 7.8 years, 55.4% female). The associations of gut microbiota and muscle had been shown in four observational studies. Probiotics, prebiotics, synbiotics, fermented milk, caloric restriction, and exercise in six studies displayed inconsistent effects on muscle mass, function, and gut microbiota.

CONCLUSIONS

Altering the gut microbiota through bacteria depletion, faecal transplantation, and various supplements was shown to directly affect muscle phenotypes. Probiotics, prebiotics, SCFAs, and bacterial products are potential novel therapies to enhance muscle mass and physical performance. Lactobacillus and Bifidobacterium strains restored age-related muscle loss. Potential mechanisms of microbiome modulating muscle mainly include protein, energy, lipid, and glucose metabolism, inflammation level, neuromuscular junction, and mitochondrial function. The role of the gut microbiota in the development of muscle loss during aging is a crucial area that requires further studies for translation to patients.

Mechanisms Linking the Gut-Muscle Axis With Muscle Protein Metabolism and Anabolic Resistance: Implications for Older Adults at Risk of Sarcopenia

Aging is associated with a decline in skeletal muscle mass and function-termed sarcopenia-as mediated, in part, by muscle anabolic resistance. This metabolic phenomenon describes the impaired response of muscle protein synthesis (MPS) to the provision of dietary amino acids and practice of resistance-based exercise. Recent observations highlight the gut-muscle axis as a physiological target for combatting anabolic resistance and reducing risk of sarcopenia. Experimental studies, primarily conducted in animal models of aging, suggest a mechanistic link between the gut microbiota and muscle atrophy, mediated via the modulation of systemic amino acid availability and low-grade inflammation that are both physiological factors known to underpin anabolic resistance. Moreover, in vivo and in vitro studies demonstrate the action of specific gut bacteria (Lactobacillus and Bifidobacterium) to increase systemic amino acid availability and elicit an anti-inflammatory response in the intestinal lumen. Prospective lifestyle approaches that target the gut-muscle axis have recently been examined in the context of mitigating sarcopenia risk. These approaches include increasing dietary fiber intake that promotes the growth and development of gut bacteria, thus enhancing the production of short-chain fatty acids (SCFA) (acetate, propionate, and butyrate). Prebiotic/probiotic/symbiotic supplementation also generates SCFA and may mitigate low-grade inflammation in older adults via modulation of the gut microbiota. Preliminary evidence also highlights the role of exercise in increasing the production of SCFA. Accordingly, lifestyle approaches that combine diets rich in fiber and probiotic supplementation with exercise training may serve to produce SCFA and increase microbial diversity, and thus may target the gut-muscle axis in mitigating anabolic resistance in older adults. Future mechanistic studies are warranted to establish the direct physiological action of distinct gut microbiota phenotypes on amino acid utilization and the postprandial stimulation of muscle protein synthesis in older adults.

Colonization Ability and Impact on Human Gut Microbiota of Foodborne Microbes From Traditional or Probiotic-Added Fermented Foods: A Systematic Review

A large subset of fermented foods act as vehicles of live environmental microbes, which often contribute food quality assets to the overall diet, such as health-associated microbial metabolites. Foodborne microorganisms also carry the potential to interact with the human gut microbiome via the food chain. However, scientific results describing the microbial flow connecting such different microbiomes as well as their impact on human health, are still fragmented. The aim of this systematic review is to provide a knowledge-base about the scientific literature addressing the connection between foodborne and gut microbiomes, as well as to identify gaps where more research is needed to clarify and map gut microorganisms originating from fermented foods, either traditional or added with probiotics, their possible impact on human gut microbiota composition and to which extent foodborne microbes might be able to colonize the gut environment. An additional aim was also to highlight experimental approaches and study designs which could be better standardized to improve comparative analysis of published datasets. Overall, the results presented in this systematic review suggest that a complex interplay between food and gut microbiota is indeed occurring, although the possible mechanisms for this interaction, as well as how it can impact human health, still remain a puzzling picture. Further research employing standardized and trans-disciplinary approaches aimed at understanding how fermented foods can be tailored to positively influence human gut microbiota and, in turn, host health, are therefore of pivotal importance.

Yearly changes in the composition of gut microbiota in the elderly, and the effect of lactobacilli intake on these changes

The onset and worsening of some diseases are related to the variation and instability of gut microbiota. However, studies examining the personal variation of gut microbiota in detail are limited. Here, we evaluated the yearly variation of individual gut microbiota in 218 Japanese subjects aged 66–91 years, using Jensen-Shannon distance (JSD) metrics. Approximately 9% of the subjects showed a substantial change, as their formerly predominant bacterial families were replaced over the year. These subjects consumed fermented milk products less frequently than their peers. The relationship between the intake frequencies of fermented milk products containing Lacticaseibacillus paracasei strain Shirota (LcS) and JSD values was also investigated. The intra-individual JSD of subjects ingesting LcS products ≥ 3 days/week over the past 10 years was statistically lower than the < 3 days/week group (P = 0.045). Focusing on subjects with substantial gut microbiota changes, only 1.7% of the subjects were included in the LcS intake ≥ 3 days/week group whereas 11.3% were found in the < 3 days/week group (P = 0.029). These results suggest that about one-tenth of the elderly Japanese could experience a substantial change in their gut microbiota during a 1-year period, and that the habitual intake of probiotics may stabilize their gut microbiota.

The Effects of Lifestyle and Diet on Gut Microbiota Composition, Inflammation and Muscle Performance in Our Aging Society

Living longer is associated with an increased risk of chronic diseases, including impairments of the musculoskeletal and immune system as well as metabolic disorders and certain cancers, each of which can negatively affect the relationship between host and microbiota up to the occurrence of dysbiosis. On the other hand, lifestyle factors, including regular physical exercise and a healthy diet, can affect skeletal muscle and immune aging positively at all ages. Accordingly, health benefits could partly depend on the effect of such interventions that influence the biodiversity and functionality of intestinal microbiota. In the present review, we first discuss the physiological effects of aging on the gut microbiota, immune system, and skeletal muscle. Secondly, we describe human epidemiological evidence about the associations between physical activity and fitness and the gut microbiota composition in older adults. The third part highlights the relevance and restorative mechanisms of immune protection through physical activity and specific exercise interventions during aging. Fourth, we present important research findings on the effects of exercise and protein as well as other nutrients on skeletal muscle performance in older adults. Finally, we provide nutritional recommendations to prevent malnutrition and support healthy active aging with a focus on gut microbiota. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low muscle mass and a higher demand for specific nutrients (e.g., dietary fiber, polyphenols and polyunsaturated fatty acids) that can modify the composition, diversity, and metabolic capacity of the gut microbiota, and may thus provide a practical means of enhancing gut and systemic immune function.

Role of Probiotics, Prebiotics, and Synbiotics in the Elderly: Insights Into Their Applications

Elderly people are an important part of the global population who suffer from the natural processes of senescence, which lead to changes in the gut microbiota composition. These modifications have a great impact on their quality of life, bringing a general putrefactive and inflammatory status as a consequence. Some of the most frequent conditions related to this status are constipation, undernutrition, neurodegenerative diseases, susceptibility to opportunistic pathogens, and metabolic disbalance, among others. For these reasons, there is an increasing interest in improving their quality of life by non-invasive treatments such as the consumption of probiotics, prebiotics, and synbiotics. The aim of the present mini-review is to describe the benefits of these functional supplements/food according to the most recent clinical and pre-clinical studies published during the last decade. In addition, insights into several aspects we consider relevant to improve the quality of future studies are provided.

Probiotic Lactobacillus casei Shirota prevents acute liver injury by reshaping the gut microbiota to alleviate excessive inflammation and metabolic disorders

Millions of people die from liver diseases annually, and liver failure is one of the three major outcomes of liver disease. The gut microbiota plays a crucial role in liver diseases. This study aimed to explore the effects of Lactobacillus casei strain Shirota (LcS), a probiotics used widely around the world, on acute liver injury (ALI), as well as the underlying mechanism. Sprague Dawley rats were intragastrically administered LcS suspensions or placebo once daily for 7 days before induction of ALI by intraperitoneal injection of D-galactosamine (D-GalN). Histopathological examination and assessments of liver biochemical markers, inflammatory cytokines, and the gut microbiota, metabolome and transcriptome were conducted. Our results showed that pretreatment with LcS reduced hepatic and intestinal damage and reduced the elevation of serum gamma-glutamyltranspeptidase (GGT), total bile acids, IL-5, IL-10, G-CSF and RANTES. The analysis of the gut microbiota, metabolome and transcriptome showed that LcS lowered the ratio of Firmicutes to Bacteroidetes; reduced the enrichment of metabolites such as chenodeoxycholic acid, deoxycholic acid, lithocholic acid, d-talose and N-acetyl-glucosamine, reduce the depletion of d-glucose and l-methionine; and alleviated the downregulation of retinol metabolism and PPAR signalling and the upregulation of the pyruvate metabolism pathway in the liver. These results indicate the promising prospect of using LcS for the treatment of liver diseases, particularly ALI.

Aging, Gut Microbiota and Metabolic Diseases: Management through Physical Exercise and Nutritional Interventions

Gut microbiota (GM) is involved in the maintenance of physiological homeostasis, thus the alteration of its composition and functionality has been associated with many pathologies such as metabolic diseases, and could also be linked with the progressive degenerative process in aging. Nowadays, life expectancy is continuously rising, so the number of elder people and the consequent related pathologies demand new strategies to achieve healthy aging. Besides, actual lifestyle patterns make metabolic diseases a global epidemic with increasing trends, responsible for a large mortality and morbidity in adulthood and also compromising the health status of later stages of life. Metabolic diseases and aging share a profile of low-grade inflammation and innate immunity activation, which may have disturbances of GM composition as the leading mechanism. Thus, GM emerges as a therapeutic target with a double impact in the elderly, counteracting both aging itself and the frequent metabolic diseases in this population. This review summarizes the role and compositional changes of the GM in aging and its modulation through nutritional interventions and physical exercise as a strategy to counteract the aging process and the related metabolic diseases.

Fermented milk containing Lactobacillus casei Zhang and Bifidobacterium animalis ssp. lactis V9 alleviated constipation symptoms through regulation of intestinal microbiota, inflammation, and metabolic pathways

Studies suggest that probiotics and fermented milk can improve defecation in constipated patients. However, the mechanism of fermented milk containing probiotics on constipation remains poorly understood. Volunteers with chronic constipation symptoms were recruited and given 200 g/d of fermented milk containing Lactobacillus casei Zhang and Bifidobacterium animalis ssp. lactis V9 (PFM) for 4 wk. Clinical symptoms, cytokines, metagenomics, and metabolomics were evaluated in constipated participants before and after PFM intervention. After PFM intervention, we observed significant improvement of constipation symptoms. In the serum samples, the anti-inflammatory cytokine IL-10 increased and the proinflammatory cytokine C-reactive protein and lipopolysaccharides decreased. Metagenomics results showed that the increase of B. animalis was correlated with an increase in defecation frequency. Fatty acid biosynthesis and bile acid biosynthesis in stool samples as well as carnitine shuttle, vitamin E metabolism, and ascorbate and aldarate metabolism were identified as significantly altered metabolic pathways. Acylcarnitine, located on the carnitine shuttle pathway, had a significantly positive correlation with defecation frequency. It was speculated that PFM may contribute to alleviating constipation symptoms through 3 potential mechanisms: fine-tuning gastrointestinal microbiota, fighting inflammation, and regulating metabolic pathways.

Effects of Physical Exercise on Autophagy and Apoptosis in Aged Brain: Human and Animal Studies

The aging process is characterized by a series of molecular and cellular changes over the years that could culminate in the deterioration of physiological parameters important to keeping an organism alive and healthy. Physical exercise, defined as planned, structured and repetitive physical activity, has been an important force to alter physiology and brain development during the process of human beings' evolution. Among several aspects of aging, the aim of this review is to discuss the balance between two vital cellular processes such as autophagy and apoptosis, based on the fact that physical exercise as a non-pharmacological strategy seems to rescue the imbalance between autophagy and apoptosis during aging. Therefore, the effects of different types or modalities of physical exercise in humans and animals, and the benefits of each of them on aging, will be discussed as a possible preventive strategy against neuronal death.

The Influence of Food Intake Specificity in Children with Autism on Gut Microbiota

Autism spectrum disorder (ASD) is a complex of neurodevelopmental conditions with increasing incidence. The microbiota of children with ASD is distinct from neurotypical children, their food habits are also different, and it is known that nutrient intake influences microbiota in a specific way. Thus, this study investigates the food habits of children with ASD and their association with the gut microbiota. Children with ASD had their dietary energy intakes similar to controls, but they more often demonstrated food selectivity, which seemed to result in deficiency of micronutrients such as vitamins K, B6, C, iron, cooper, docosahexaenoic and docosapentanoic acid. Using high-throughput sequencing, a DNA library of intestinal microbiota was performed. Core microbiota was similar in children with and without ASD, but Dichelobacter, Nitriliruptor and Constrictibacter were found to be putative markers of ASD. The changes in gut microbiota that we observed in connection to food selectivity, intake of fats and omega-3 in particular, fermented milk products and animal/plant protein consumption had similar character, independent of diagnosis. However, high fibre intake was connected with a decreased α-diversity only in children with ASD. High carbohydrate and fibre intake influenced β-diversity, changing the abundance of Bacteroides and other genera, many of them members of the Clostidiaceae. Modulating food habits of ASD children can influence their gut microbiota composition.