Composition of dietary fat source shapes gut microbiota architecture and alters host inflammatory mediators in mouse adipose tissue

Potential of Synbiotics and Probiotics as Chemopreventive Agent

Cancer remains a global problem, with millions of new cases diagnosed yearly and countless lives lost. The financial burden of cancer therapy, along with worries about the long-term safety of existing medicines, necessitates the investigation of alternative approaches to cancer prevention. Probiotics generate chemopreventive compounds such as bacteriocins, short-chain fatty acids (SCFA), and extracellular polymeric substances (EPS), which have demonstrated the ability to impede cancer cell proliferation, induce apoptosis, and bolster the expression of pro-apoptotic genes. On the other hand, prebiotics, classified as non-digestible food ingredients, promote the proliferation of probiotics within the colon, thereby ensuring sustained functionality of the gut microbiota. Consequently, the synergistic effect of combining prebiotics with probiotics, known as the synbiotic effect, in dietary interventions holds promise for potentially mitigating cancer risk and augmenting preventive measures. The utilization of gut microbiota in cancer treatment has shown promise in alleviating adverse health effects. This review explored the potential and the role of probiotics and synbiotics in enhancing health and contributing to cancer prevention efforts. In this review, the applications of functional probiotics and synbiotics, the mechanisms of action of probiotics in cancer, and the relationship of probiotics with various drugs were discussed, shedding light on the potential of probiotics and synbiotics to alleviate the burdens of cancer treatment.

Contaminant Biomagnification in Polar Bears: Interindividual Differences, Dietary Intake Rate, and the Gut Microbiome

Some persistent hydrophobic pollutants biomagnify, i.e., achieve higher contaminant levels in a predator than in its prey (Cpredator/Cprey > 1). This ratio is called the biomagnification factor (BMF) and is traditionally determined using tissues from carcasses or biopsies. Using a noninvasive method that relies on equilibrium sampling in silicone-film-coated vessels and chemical analysis of paired diet and feces, we determined on three occasions the thermodynamic biomagnification limit (BMFlim) and feces-based biomagnification factor (BMFF) for three zoo-housed polar bears who experience seasonal periods of hyperphagia and hypophagia. All bears had high biomagnification capabilities (BMFlim was up to 200) owing to very efficient lipid assimilation (up to 99.5%). The bears differed up to a factor of 3 in their BMFlim. BMFlim and BMFF of a bear increased by up to a factor of 4 during the hypophagic period, when the ingestion rate was greatly reduced. Much of that variability can be explained by differences in the lipid assimilation efficiency, even though this efficiency ranged only from 98.1 to 99.5%. A high BMFlim was associated with a high abundance of Bacteroidales and Lachnospirales in the gut microbiome. Biomagnification varies to a surprisingly large extent between individuals and within the same individual over time. Future work should investigate whether this can be attributed to the influence of the gut microbiome on lipid assimilation by studying more individual bears at different key physiological stages.

Diet-Induced Rodent Obesity Is Prevented and the Fecal Microbiome Is Improved with Elderberry (Sambucus nigra ssp. canadensis) Juice Powder

Anthocyanin-rich edible berries protect against diet-induced obesity in animal models. Prevention is mediated through the bidirectional relationship with the fecal microbiome, and gut-derived phenolic metabolite absorption increases with physical activity, which may influence bioactivity. The objective of this study was to test elderberry juice powder on the development of diet-induced obesity and its influence on the fecal microbiome alone or in combination with physical activity. Male C57BL/6J mice were assigned to one of four treatments, including (1) high-fat diet without wheel access; (2) high-fat diet with unlimited wheel access; (3) high-fat diet supplemented with 10% elderberry juice powder without wheel access; and (4) high-fat diet supplemented with 10% elderberry juice powder with unlimited wheel access. Body weight gain, fat pads, and whole-body fat content in mice fed elderberry juice were significantly less than in mice fed the control diet independent of wheel access. At the end of the study, active mice fed elderberry juice ate significantly more than active mice fed a control diet. There was no difference in the physical activity between active groups. Elderberry juice increasedBifidobacterium, promotedAkkermansia and Anaeroplasma, and prevented the growth of Desulfovibrio. Elderberry juice is a potent inhibitor of diet-induced obesity with action mediated by the gut microbiota.

Oils with different degree of saturation: effects on ileal digestibility of fat and corresponding additivity and bacterial community in growing pigs

BACKGROUND

Oils are important sources of energy in pig diets. The combination of oils with different degree of saturation contributes to improve the utilization efficiency of the mixed oils and may reduce the cost of oil supplemented. An experiment was conducted to evaluate the effects of oils with different degree of saturation on the fat digestibility and corresponding additivity and bacterial community in growing pigs.

METHODS

Eighteen crossbred (Duroc × Landrace × Yorkshire) barrows (initial body weight: 29.3 ± 2.8 kg) were surgically fitted with a T-cannula in the distal ileum. The experimental diets included a fat-free basal diet and 5 oil-added diets. The 5 oil-added diets were formulated by adding 6% oil with different ratio of unsaturated to saturated fatty acids (U:S) to the basal diet. The 5 oils were palm oil (U:S = 1.2), canola oil (U:S = 12.0), and palm oil and canola oil were mixed in different proportions to prepare a combination of U:S of 2.5, 3.5 and 4.5, respectively.

RESULTS

The apparent and standardized ileal digestibility (AID and SID) of fat and fatty acids increased linearly (P < 0.05) as the U:S of dietary oils increased except for SID of fat and C18:2. The AID and SID of fat and fatty acids differed among the dietary treatments (P < 0.05) except for SID of unsaturated fatty acids (UFA) and C18:2. Fitted one-slope broken-line analyses for the SID of fat, saturated fatty acids (SFA) and UFA indicated that the breakpoint for U:S of oil was 4.14 (R2 = 0.89, P < 0.01), 2.91 (R2 = 0.98, P < 0.01) and 3.84 (R2 = 0.85, P < 0.01), respectively. The determined SID of fat, C18:1, C18:2 and UFA in the mixtures was not different from the calculated SID of fat, C18:1, C18:2 and UFA. However, the determined SID of C16:0, C18:0 and SFA in the mixtures were greater than the calculated SID values (P < 0.05). The abundance of Romboutsia and Turicibacter in pigs fed diet containing palm oil was greater than that in rapeseed oil treatment group, and the two bacteria were negatively correlated with SID of C16:0, C18:0 and SFA (P < 0.05).

CONCLUSIONS

The optimal U:S for improving the utilization efficiency of mixed oil was 4.14. The SID of fat and UFA for palm oil and canola oil were additive in growing pigs, whereas the SID of SFA in the mixture of two oils was greater than the sum of the values of pure oils. Differences in fat digestibility caused by oils differing in degree of saturation has a significant impact on bacterial community in the foregut.

Chronic blue light-emitting diode exposure harvests gut dysbiosis related to cholesterol dysregulation

Night shift workers have been associated with circadian dysregulation and metabolic disorders, which are tightly coevolved with gut microbiota. The chronic impacts of light-emitting diode (LED) lighting at night on gut microbiota and serum lipids were investigated. Male C57BL/6 mice were exposed to blue or white LED lighting at Zeitgeber time 13.5-14 (ZT; ZT0 is the onset of "lights on" and ZT12 is the "lights off" onset under 12-hour light, 12-hour dark schedule). After 33 weeks, only the high irradiance (7.2 J/cm2) of blue LED light reduced the alpha diversity of gut microbiota. The high irradiance of white LED light and the low irradiance (3.6 J/cm2) of both lights did not change microbial alpha diversity. However, the low irradiance, but not the high one, of both blue and white LED illuminations significantly increased serum total cholesterol (TCHO), but not triglyceride (TG). There was no significant difference of microbial abundance between two lights. The ratio of beneficial to harmful bacteria decreased at a low irradiance but increased at a high irradiance of blue light. Notably, this ratio was negatively correlated with serum TCHO but positively correlated with bile acid biosynthesis pathway. Therefore, chronic blue LED lighting at a high irradiance may harvest gut dysbiosis in association with decreased alpha diversity and the ratio of beneficial to harmful bacteria to specifically dysregulates TCHO metabolism in mice. Night shift workers are recommended to be avoid of blue LED lighting for a long and lasting time.

On the road to colorectal cancer development: crosstalk between the gut microbiota, metabolic reprogramming, and epigenetic modifications

An increasing number of studies have reported the role of gut microbes in colorectal cancer (CRC) development, as they can be influenced by dietary metabolism and mediate alterations in host epigenetics, ultimately affecting CRC. Intake of specific dietary components can affect gut microbial composition and function, and their metabolism regulates important epigenetic functions that may influence CRC risk. Gut microbes can regulate epigenetic modifications through nutrient metabolism, including histone modification, DNA methylation, and noncoding RNAs. Epigenetics, in turn, determines the gut microbial composition and thus influences the risk of developing CRC. This review discusses the complex crosstalk between metabolic reprogramming, gut microbiota, and epigenetics in CRC and highlights the potential applications of the gut microbiota as a biomarker for the prevention, diagnosis, and therapy of CRC.

Dietary components regulate chronic diseases through gut microbiota: a review

In recent years, gut microbiota as an immune organ has gradually become the mainstream of research. When the composition of the gut microbiota is changed significantly, this may affect human health. This review details the major microbiota composition and metabolites in the gut and discusses chronic diseases based on gut dysbiosis, including obesity, liver injury, colon cancer, atherosclerosis, and central nervous system diseases. We comprehensively summarize the changes in abundance of relevant gut microbiota by ingesting different diet components (such as food additives, dietary polyphenols, polysaccharides, fats, proteins) and their influence on the microbial quorum sensing system, thereby regulating related diseases. We believe that quorum sensing can be used as a new entry point to explain the mechanism of ingesting dietary components to improve gut microbiota and thereby regulate related diseases. This review hopes to provide a theoretical basis for future research on improving disease symptoms by ingesting functional foods containing dietary components. © 2023 Society of Chemical Industry.

Effect of the oil from the fatty tissues of Crocodylus siamensis on gut microbiome diversity and metabolism in mice

Dietary fat can alter host metabolism and gut microbial composition. Crocodile oil (CO) was extracted from the fatty tissues of Crocodylus siamensis. CO, rich in monounsaturated- and polyunsaturated fatty acids, has been reported to reduce inflammation, counter toxification, and improve energy metabolism. The aim of this study was to investigate the effect of CO on gut microbiota (GM) in laboratory mice as well as the accompanying metabolic changes in the animals. Forty-five C57BL/6 male mice were randomly divided into five groups and orally administrated either sterile water (control [C]); 1 or 3% (v/w) CO (CO-low [CO-L] and CO-high [CO-H], respectively); or 1 or 3% (v/w) palm oil (PO-low and PO-high, respectively) for 11 weeks. Body weight gain, food intake, energy intake, blood glucose levels, and blood lipid profiles were determined. Samples from colon tissue were collected and the 16S rRNA genes were pyrosequenced to clarify GM analyses. The results showed that there were no differences in body weight and blood glucose levels. Food intake by the mice in the CO-L and CO-H groups was statistically significantly less when compared to that by the animals in the C group. However, neither CO treatment had a statistically significant effect on calorie intake when compared to the controls. The CO-H exhibited a significant increase in serum total cholesterol and low-density lipoprotein but showed a downward trend in triglyceride levels compared to the control. The GM analyses revealed that both CO treatments have no significant influence on bacterial diversity and relative abundance at the phylum level, whereas increases of Choa1 and abundance-based coverage estimator indexes, distinct β-diversity, and Proteobacteria abundance were observed in the PO-high group compared with the C group. Furthermore, the abundance of Azospirillum thiophilum and Romboutsia ilealis was significantly higher in the CO-L and CO-H groups which could be associated with energy metabolic activity. Thus, CO may be an alternative fat source for preserving host metabolism and gut flora.

Inflammatory crosstalk between saturated fatty acids and gut microbiota-white adipose tissue axis

PURPOSE

High-fat diets have different metabolic responses via gut dysbiosis. In this review, we discuss the complex interaction between the intake of long- and medium-chain saturated fatty acids (SFAs), gut microbiota, and white adipose tissue (WAT) dysfunction, particularly focusing on the type of fat.

RESULTS

The evidence for the impact of dietary SFAs on the gut microbiota-WAT axis has been mostly derived from in vitro and animal models, but there is now also evidence emerging from human studies. Most current reports show that, in response to high long- and medium-chain SFA diets, WAT functions are altered and can be modulated from microbial metabolites in several manners; and it appears to be also modified under conditions of obesity. SFAs overconsumption can reduce bacterial content and disrupt the gut environment. Both long- and medium-chain SFAs may contribute to proinflammatory cytokines release and TLR4 cascade signaling, either by regulation of endotoxemia markers or myristoylated protein. Palmitic and stearic acids have pathological effects on the intestinal epithelium, microbes, and inflammatory and lipogenic WAT profiles. While myristic and lauric acids display somewhat controversial outcomes, from probiotic effects and contribution to weight loss to cardiometabolic alterations from WAT inflammation.

CONCLUSION

Identifying an interference of distinct types of SFA in the binomial gut microbiota-WAT may elucidate essential mechanisms of metabolic endotoxemia, which may be the key to triggering obesity, innovating the therapeutic tools for this disease.

Time-Restricted Feeding Modifies the Fecal Lipidome and the Gut Microbiota

Time-restricted feeding (TRF) has been identified as an approach to reduce the risk of obesity-related metabolic diseases. We hypothesize that TRF triggers a change in nutrient (e.g., dietary fat) absorption due to shortened feeding times, which subsequently alters the fecal microbiome and lipidome. In this report, three groups of C57BL/6 mice were fed either a control diet with ad libitum feeding (16% energy from fat) (CTRL-AL), a high-fat diet (48% energy from fat) with ad libitum feeding (HF-AL), or a high-fat diet with time-restricted feeding (HF-TRF) for 12 weeks. No changes in microbiota at the phylum level were detected, but eight taxonomic families were altered by either feeding timing or dietary fat content. The HF-AL diet doubled the total fecal fatty acid content of the CTRL-AL diet, while the HF-TRF doubled the total fecal fatty acid content of the HF-AL diet. Primary fecal bile acids were unaffected by diet. Total short-chain fatty acids were reduced by HF-AL, but this effect was diminished by HF-TRF. Each diet produced distinct relationships between the relative abundance of taxa and fecal lipids. The anti-obesogenic effects of TRF in HF diets are partly due to the increase in fat excretion in the feces. Furthermore, fat content and feeding timing differentially affect the fecal microbiota and the relationship between the microbiota and fecal lipids.

Omega-3-Supplemented Fat Diet Drives Immune Metabolic Response in Visceral Adipose Tissue by Modulating Gut Microbiota in a Mouse Model of Obesity

Obesity is a chronic, relapsing, and multifactorial disease characterized by excessive accumulation of adipose tissue (AT), and is associated with inflammation mainly in white adipose tissue (WAT) and an increase in pro-inflammatory M1 macrophages and other immune cells. This milieu favors the secretion of cytokines and adipokines, contributing to AT dysfunction (ATD) and metabolic dysregulation. Numerous articles link specific changes in the gut microbiota (GM) to the development of obesity and its associated disorders, highlighting the role of diet, particularly fatty acid composition, in modulating the taxonomic profile. The aim of this study was to analyze the effect of a medium-fat-content diet (11%) supplemented with omega-3 fatty acids (D2) on the development of obesity, and on the composition of the GM compared with a control diet with a low fat content (4%) (D1) over a 6-month period. The effect of omega-3 supplementation on metabolic parameters and the modulation of the immunological microenvironment in visceral adipose tissue (VAT) was also evaluated. Six-weeks-old mice were adapted for two weeks and then divided into two groups of eight mice each: a control group D1 and the experimental group D2. Their body weight was recorded at 0, 4, 12, and 24 weeks post-differential feeding and stool samples were simultaneously collected to determine the GM composition. Four mice per group were sacrificed on week 24 and their VAT was taken to determine the immune cells phenotypes (M1 or M2 macrophages) and inflammatory biomarkers. Blood samples were used to determine the glucose, total LDL and HDL cholesterol LDL, HDL and total cholesterol, triglycerides, liver enzymes, leptin, and adiponectin. Body weight measurement showed significant differences at 4 (D1 = 32.0 ± 2.0 g vs. D2 = 36.2 ± 4.5 g, p-value = 0.0339), 12 (D1 = 35.7 ± 4.1 g vs. D2 = 45.3 ± 4.9 g, p-value = 0.0009), and 24 weeks (D1 = 37.5 ± 4.7 g vs. D2 = 47.9 ± 4.7, p-value = 0.0009). The effects of diet on the GM composition changed over time: in the first 12 weeks, α and β diversity differed considerably according to diet and weight increase. In contrast, at 24 weeks, the composition, although still different between groups D1 and D2, showed changes compared with previous samples, suggesting the beneficial effects of omega-3 fatty acids in D2. With regard to metabolic analysis, the results did not reveal relevant changes in biomarkers in accordance with AT studies showing an anti-inflammatory environment and conserved structure and function, which is in contrast to reported findings for pathogenic obesity. In conclusion, the results suggest that the constant and sustained administration of omega-3 fatty acids induced specific changes in GM composition, mainly with increases in Lactobacillus and Ligilactobacillus species, which, in turn, modulated the immune metabolic response of AT in this mouse model of obesity.

Imbalanced gut microbiota predicts and drives the progression of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis in a fast-food diet mouse model

Nonalcoholic fatty liver disease (NAFLD) is multifactorial in nature, affecting over a billion people worldwide. The gut microbiome has emerged as an associative factor in NAFLD, yet mechanistic contributions are unclear. Here, we show fast food (FF) diets containing high fat, added cholesterol, and fructose/glucose drinking water differentially impact short- vs. long-term NAFLD severity and progression in conventionally-raised, but not germ-free mice. Correlation and machine learning analyses independently demonstrate FF diets induce early and specific gut microbiota changes that are predictive of NAFLD indicators, with corresponding microbial community instability relative to control-fed mice. Shotgun metagenomics showed FF diets containing high cholesterol elevate fecal pro-inflammatory effectors over time, relating to a reshaping of host hepatic metabolic and inflammatory transcriptomes. FF diet-induced gut dysbiosis precedes onset and is highly predictive of NAFLD outcomes, providing potential insights into microbially-based pathogenesis and therapeutics.

The modulatory effect of encapsulated bioactives and probiotics on gut microbiota: improving health status through functional food

The gut microbiota can be a determining factor of the health status of the host by its association with some diseases. It is known that dietary intake can modulate this microbiota through the consumption of compounds like essential oils, unsaturated fatty acids, non-digestible fiber, and probiotics, among others. However, these kinds of compounds can be damaged in the gastrointestinal tract as they pass through it to reach the intestine. This is due to the aggressive and changing conditions of this tract. For this reason, to guarantee that compounds arrive in the intestine at an adequate concentration to exert a modulatory effect on the gut microbiota, encapsulation should be sought. In this paper, we review the current research on compounds that modulate the gut microbiota, the encapsulation techniques used to protect the compounds through the gastrointestinal tract, in vitro models of this tract, and how these encapsulates interact with the gut microbiota. Finally, an overview of the regulatory status of these encapsulates is presented. The key findings are that prebiotics are the best modulators of gut microbiota fermentation metabolites. Also, probiotics promote an increase of beneficial gut microorganisms, which in some cases promotes their fermentation metabolites as well. Spray drying, freeze drying, and electrodynamics are notable encapsulation techniques that permit high encapsulation efficiency, high viability, and, together with wall materials, a high degree of protection against gastrointestinal conditions, allowing controlled release in the intestine and exerting a modulatory effect on gut microbiota.

Dietary Combination of Fish Oil and Soy β-Conglycinin Inhibits Fat Accumulation and Reduces Blood Glucose Levels by Altering Gut Microbiome Composition in Diabetic/Obese KK-A y Mice

Dietary fish oil containing n-3 polyunsaturated fatty acids provides health benefits by lowering lipid levels in the liver and serum. β-Conglycinin (βCG) is a major constituent protein in soybean with many physiological effects, such as lowering blood triglyceride levels, preventing obesity and diabetes, and improving hepatic lipid metabolism. However, the combined effects of fish oil and βCG remain unclear. Here, we investigated the effects of a dietary combination of fish oil and βCG on lipid and glucose parameters in diabetic/obese KK-A ^y mice. KK-A ^y mice were divided into three groups: control, fish oil, and fish oil + βCG; these groups were fed a casein-based diet containing 7% (w/w) soybean oil, a casein-based diet containing 2% (w/w) soybean oil and 5% (w/w) fish oil, and a βCG-based diet containing 2% (w/w) soybean oil and 5% (w/w) fish oil, respectively. The effects of the dietary combination of fish oil and βCG on blood biochemical parameters, adipose tissue weight, expression levels of fat- and glucose metabolism-related genes, and cecal microbiome composition were evaluated. The total white adipose tissue weight (p < 0.05), levels of total serum cholesterol (p < 0.01), triglyceride (p < 0.01), and blood glucose (p < 0.05), and expression levels of fatty acid synthesis-related genes (including Fasn (p < 0.05) and Acc (p < 0.05)), and glucose metabolism-related genes (such as Pepck (p < 0.05)) were lower in the fish oil and fish oil + βCG groups than in the control group. Furthermore, the relative abundance of Bacteroidaceae and Coriobacteriaceae differed significantly between the fish oil + βCG and control groups. These findings suggest that dietary intake of fish oil + βCG may prevent obesity and diabetes, alleviate lipid abnormalities, and alter the gut microbiome composition in diabetic/obese KK-A ^y mice. Further research is needed to build on this study to evaluate the health benefits of major components of Japanese food.

Major dietary lipids in nutrition and health

In this chapter, an overview of the major lipids in the diet with emphasis in nutritional aspects is provided. Triacylglycerols, i.e., glycerol esterified with three fatty acids, are the predominant constituents in dietary lipids. Therefore, this chapter focuses on the nature and nutritional significance of the main fatty acids in the diet and their possible modifications during food processing and commercialization. The main fatty acids in dietary lipids are grouped into saturated, monounsaturated and polyunsaturated fatty acids. Nutritional implications, the latest intervention trials and health recommendations will be discussed. A brief description of the major sources of lipids in the diet is included, oils and fats standing out. Other food sources shortly commented are milk and dairy products, meat, poultry and eggs, fish, and structured lipids designed to improve functional and nutritional properties. Modifications of fatty acids as a result of processing and commercialization are discussed because of their great relevance for their health implications, especially oxidation compounds and trans fatty acids.

Evaluation of the ability of fatty acid metabolism signature to predict response to neoadjuvant chemoradiotherapy and prognosis of patients with locally advanced rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) is widely used to treat patients with locally advanced rectal cancer (LARC), and treatment responses vary. Fatty acid metabolism (FAM) is closely associated with carcinogenesis and cancer progression. In this study, we investigated the vital role of FAM on the gut microbiome and metabolism in the context of cancer. We screened 34 disease-free survival (DFS)-related, FAM-related, and radiosensitivity-related genes based on the Gene Expression Omnibus database. Subsequently, we developed a five-gene FAM-related signature using the least absolute shrinkage and selection operator Cox regression model. The FAM-related signature was also validated in external validation from Fujian Cancer Hospital for predicting nCRT response, DFS, and overall survival (OS). Notably, patients with a low-risk score were associated with pathological complete response and better DFS and OS outcomes. A comprehensive evaluation of the tumor microenvironment based on the FAM-related signature revealed that patients with high-risk scores were closely associated with activating type I interferon response and inflammation-promoting functions. In conclusion, our findings indicate the potential ability of FAM to predict nCRT response and the prognosis of DFS and OS in patients with LARC.

Effect of 30 days of ketogenic Mediterranean diet with phytoextracts on athletes' gut microbiome composition

Background

Recent research suggest that gut microbiome may play a fundamental role in athlete's health and performance. Interestingly, nutrition can affect athletic performance by influencing the gut microbiome composition. Among different dietary patterns, ketogenic diet represents an efficient nutritional approach to get adequate body composition in athletes, however, some concerns have been raised about its potential detrimental effect on gut microbiome. To the best of our knowledge, only one study investigated the effect of ketogenic diet on the gut microbiome in athletes (elite race walkers), whilst no studies are available in a model of mixed endurance/power sport such as soccer. This study aimed to investigate the influence of a ketogenic Mediterranean diet with phytoextracts (KEMEPHY) diet on gut microbiome composition in a cohort of semi-professional soccer players.

Methods

16 male soccer players were randomly assigned to KEMEPHY diet (KDP n = 8) or western diet (WD n = 8). Body composition, performance measurements and gut microbiome composition were measured before and after 30 days of intervention by 16S rRNA amplicon sequencing. Alpha-diversity measures and PERMANOVA was used to investigate pre-post differences in the relative abundance of all taxonomic levels (from phylum to genus) and Spearman's correlations was used to investigate associations between microbial composition and macronutrient intake. Linear discriminant analysis was also performed at the different taxonomic levels on the post-intervention data.

Results

No differences were found between pre and post- dietary intervention for microbial community diversity: no significant effects of time (p = 0.056, ES = 0.486 and p = 0.129, ES = 0.388, respectively for OTUs number and Shannon's ENS), group (p = 0.317, ES = 0.180 and p = 0.809, ES = 0.047) or time × group (p = 0.999, ES = 0.01 and p = 0.230, ES = 0.315). Post-hoc paired Wilcoxon test showed a significant time × group effect for Actinobacteriota (p = 0.021, ES = 0.578), which increased in the WD group (median pre: 1.7%; median post: 2.3%) and decreased in the KEMEPHY group (median pre: 4.3%; median post: 1.7%). At genus level, the linear discriminant analysis in the post intervention differentiated the two groups for Bifidobacterium genus (pertaining to the Actinobacteria phylum), Butyricicoccus and Acidaminococcus genera, all more abundant in the WD group, and for Clostridia UCG-014 (order, family, and genus), Butyricimonas, Odoribacterter genera (pertaining to the Marinifilaceae family), and Ruminococcus genus, all more abundant in the KEMEPHY group.

Conclusions

Our results demonstrate that 30 days of KEMEPHY intervention, in contrast with previous research on ketogenic diet and gut microbiome, do not modify the overall composition of gut microbiome in a cohort of athletes. KEMEPHY dietary pattern may represent an alternative and safety tool for maintaining and/or regulating the composition of gut microbiome in athletes practicing regular exercise. Due to the fact that not all ketogenic diets are equal, we hypothesized that each version of ketogenic diet, with different kind of nutrients or macronutrients partitioning, may differently affect the human gut microbiome.

Dietary fat quality impacts metabolic impairments of type 2 diabetes risk differently in male and female CD-1® mice

Metabolic impairments associated with type 2 diabetes, including insulin resistance and loss of glycaemic control, disproportionately impact the elderly. Lifestyle interventions, such as manipulation of dietary fat quality (i.e. fatty acid (FA) composition), have been shown to favourably modulate metabolic health. Yet, whether or not chronic consumption of beneficial FAs can protect against metabolic derangements and disease risk during ageing is not well defined. We sought to evaluate whether long-term dietary supplementation of fish-, dairy- or echium-derived FAs to the average FA profile in a U.S. American diet may offset metabolic impairments in males and females during ageing. One-month-old CD-1^® mice were fed isoenergetic, high-fat (40 %) diets with the fat content composed of either 100 % control fat blend (CO) or 70 % CO with 30 % fish oil, dairy fat or echium oil for 13 months. Every 3 months, parameters of glucose homoeostasis were evaluated via glucose and insulin tolerance tests. Glucose tolerance improved in males consuming a diet supplemented with fish oil or echium oil as ageing progressed, but not in females. Yet, females were more metabolically protected than males regardless of age. Additionally, Spearman correlations were performed between indices of glucose homoeostasis and previously reported measurements of diet-derived FA content in tissues and colonic bacterial composition, which also revealed sex-specific associations. This study provides evidence that long-term dietary fat quality influences risk factors of metabolic diseases during ageing in a sex-dependent manner; thus, sex is a critical factor to be considered in future dietary strategies to mitigate type 2 diabetes risk.

Ingestion of remediated lead-contaminated soils affects the fecal microbiome of mice

The relationship between ingestion of diets amended with a Pb-contaminated soil and the composition of the fecal microbiome was examined in a mouse model. Mice consumed diets amended with a Pb-contaminated soil in its native (untreated) state or after treatment for remediation with phosphoric acid or triple superphosphate alone or in combination with iron-waste material or biosolids compost. Subacute dietary exposure of mice receiving treated soil resulted in modulation of the fecal intestinal flora, which coincided with reduced relative Pb bioavailability in the bone, blood and kidney and differences in Pb speciation compared to untreated soil. Shifts in the relative abundance of several phyla including Verrucomicrobia, Tenericutes, Firmicutes, Proteobacteria, and TM7 (Candidatus Saccharibacteria) were observed. Because the phyla persist in the presence of Pb, it is probable that they are resistant to Pb. This may enable members of the phyla to bind and limit Pb uptake in the intestine. Families Ruminococcaceae, Lachnospiraceae, Erysipelotrichaceae, Verrucomicrobiaceae, Prevotellaceae, Lactobacilaceae, and Bacteroidaceae, which have been linked to health or disease, also were modulated. This study is the first to explore the relationship between the murine fecal microbiome and ingested Pb contaminated soils treated with different remediation options designed to reduce bioavailability. Identifying commonalities in the microbiome that are correlated with more positive health outcomes may serve as biomarkers to assist in the selection of remediation approaches that are more effective and pose less risk.

Diet Is a Stronger Covariate than Exercise in Determining Gut Microbial Richness and Diversity

Obesity is a common metabolic disorder caused by a sedentary lifestyle, and a high-fat and a high-glucose diet in the form of fast foods. High-fat diet-induced obesity is a major cause of diabetes and cardiovascular diseases, whereas exercise and physical activity can ameliorate these disorders. Moreover, exercise and the gut microbiota are known to be interconnected, since exercise can increase the gut microbial diversity and contribute to the beneficial health effects. In this context, we analyzed the effect of diet and exercise on the gut microbiota of mice, by next-generation sequencing of the bacterial V4 region of 16S rRNA. Briefly, mice were divided into four groups: chow-diet (CD), high-fat diet (HFD), high-fat diet + exercise (HFX), and exercise-only (EX). The mice underwent treadmill exercise and diet intervention for 8 weeks, followed by the collection of their feces and DNA extraction for sequencing. The data were analyzed using the QIIME 2 bioinformatics platform and R software to assess their gut microbial composition, richness, and diversity. The Bacteroidetes to Firmicutes ratio was found to be decreased manifold in the HFD and HFX groups compared to the CD and EX groups. The gut microbial richness was comparatively lower in the HFD and HFX groups and higher in the CD and EX groups (ACE, Chao1, and observed OTUs). However, the Shannon alpha diversity index was higher in the HFD and HFX groups than in the CD and EX groups. The beta diversity based on Jaccard, Bray-Curtis, and weighted UniFrac distance metrics was significant among the groups, as measured by PERMANOVA. Paraprevotella, Desulfovibrio, and Lactococcus were the differentially abundant/present genera based on the intervention groups and in addition to these three bacteria, Butyricimonas and Desulfovibrio C21c20 were differentially abundant/present based on diet. Hence, diet significantly contributed to the majority of the changes in the gut microbiota.

How Diet and Physical Activity Modulate Gut Microbiota: Evidence, and Perspectives

Gut microbiota plays a significant role in the maintenance of physiological homeostasis, contributing to human health. Nevertheless, some factors (sex, age, lifestyle, physical activity, drug-based therapies, diet, etc.) affect its composition and functionality, linked to pathologies and immunological diseases. Concerning diet, it interacts with microorganisms, leading to beneficial or detrimental outcomes for the health of host. On the other hand, physical activity is known to be useful for preventing and, sometimes, treating several diseases of cardiovascular, neuroendocrine, respiratory, and muscular systems. This paper focuses on diet and physical activity presenting the current knowledge about how different diets (Western, ketogenic, vegan, gluten free, Mediterranean) as well as different types of exercise (intensive, endurance, aerobic) could shape gut microbiota.

The Role of Gut Microbiota in the Skeletal Muscle Development and Fat Deposition in Pigs

Pork quality is a factor increasingly considered in consumer preferences for pork. The formation mechanisms determining meat quality are complicated, including endogenous and exogenous factors. Despite a lot of research on meat quality, unexpected variation in meat quality is still a major problem in the meat industry. Currently, gut microbiota and their metabolites have attracted increased attention in the animal breeding industry, and recent research demonstrated their significance in muscle fiber development and fat deposition. The purpose of this paper is to summarize the research on the effects of gut microbiota on pig muscle and fat deposition. The factors affecting gut microbiota composition will also be discussed, including host genetics, dietary composition, antibiotics, prebiotics, and probiotics. We provide an overall understanding of the relationship between gut microbiota and meat quality in pigs, and how manipulation of gut microbiota may contribute to increasing pork quality for human consumption.

The impacts of bovine milk, soy beverage, or almond beverage on the growing rat microbiome

Background

Milk, the first food of mammals, helps to establish a baseline gut microbiota. In humans, milk and milk products are consumed beyond infancy, providing comprehensive nutritional value. Non-dairy beverages, produced from plant, are increasingly popular as alternatives to dairy milk. The nutritive value of some plant-based products continues to be debated, whilst investigations into impacts on the microbiome are rare. The aim of this study was to compare the impact of bovine milk, soy and almond beverages on the rat gut microbiome. We previously showed soy and milk supplemented rats had similar bone density whereas the almond supplemented group had compromised bone health. There is an established link between bone health and the microbiota, leading us to hypothesise that the microbiota of groups supplemented with soy and milk would be somewhat similar, whilst almond supplementation would be different.

Methods

Three-week-old male Sprague Dawley rats were randomly assigned to five groups (n = 10/group) and fed ad libitum for four weeks. Two control groups were fed either standard diet (AIN-93G food) or AIN-93G amino acids (AA, containing amino acids equivalent to casein but with no intact protein) and with water provided ad libitum. Three treatment groups were fed AIN-93G AA and supplemented with either bovine ultra-heat treatment (UHT) milk or soy or almond UHT beverages as their sole liquid source. At trial end, DNA was extracted from caecum contents, and microbial abundance and diversity assessed using high throughput sequencing of the V3 to V4 variable regions of the 16S ribosomal RNA gene.

Results

Almost all phyla (91%) differed significantly (FDR < 0.05) in relative abundance according to treatment and there were distinct differences seen in community structure between treatment groups at this level. At family level, forty taxa showed significantly different relative abundance (FDR < 0.05). Bacteroidetes (Bacteroidaceae) and Firmicutes populations (Lactobacillaceae, Clostridiaceae and Peptostreptococcaceae) increased in relative abundance in the AA almond supplemented group. Supplementation with milk resulted in increased abundance of Actinobacteria (Coriobacteriaceae and Bifidobacteriaceae) compared with other groups. Soy supplementation increased abundance of some Firmicutes (Lactobacilliaceae) but not Actinobacteria, as previously reported by others.

Conclusion

Supplementation with milk or plant-based drinks has broad impacts on the intestinal microbiome of young rats. Changes induced by cow milk were generally in line with previous reports showing increased relative abundance of Bifidobacteriacea, whilst soy and almond beverage did not. Changes induced by soy and almond drink supplementation were in taxa commonly associated with carbohydrate utilisation. This research provides new insight into effects on the microbiome of three commercially available products marketed for similar uses.

The Role of Dietary Fats in the Development and Prevention of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a significant cause of mortality and morbidity in preterm infants. The pathogenesis of NEC is not completely understood; however, intestinal immaturity and excessive immunoreactivity of intestinal mucosa to intraluminal microbes and nutrients appear to have critical roles. Dietary fats are not only the main source of energy for preterm infants, but also exert potent effects on intestinal development, intestinal microbial colonization, immune function, and inflammatory response. Preterm infants have a relatively low capacity to digest and absorb triglyceride fat. Fat may thereby accumulate in the ileum and contribute to the development of NEC by inducing oxidative stress and inflammation. Some fat components, such as long-chain polyunsaturated fatty acids (LC-PUFAs), also exert immunomodulatory roles during the early postnatal period when the immune system is rapidly developing. LC-PUFAs may have the ability to modulate the inflammatory process of NEC, particularly when the balance between n3 and n6 LC-PUFAs derivatives is maintained. Supplementation with n3 LC-PUFAs alone may have limited effect on NEC prevention. In this review, we describe how various fatty acids play different roles in the pathogenesis of NEC in preterm infants.

High Vaccenic Acid Content in Beef Fat Attenuates High Fat and High Carbohydrate Western Diet Induced Changes in Lipid Metabolism and Gut Microbiota in Pigs

High-fat diets (HFD) have been shown to induce substantial shifts in intestinal microbial community composition and activity which are associated with adverse metabolic outcomes. Furthermore, changes in microbial composition are affected by fatty acid composition; saturated, monounsaturated (MUFA), and industrial trans fats (iTFA) adversely affect microbial diversity while polyunsaturated fats (PUFA) have been shown to have neutral effects. The effects of naturally occurring trans fats on gut microbial composition are unknown. Vaccenic acid (VA) is the most abundant naturally occurring trans fat (abundant in meat and dairy), can be elevated by altering a cow's diet, and has been shown to have hypolipidemic effects. The aim of this study was to determine how variations of VA content in beef fat affect gut microbial composition, insulin resistance, and lipid metabolism in pigs. Low birth weight (LBW) and control pigs were fed a control or high-fat, high-carbohydrate (HFHC) diet supplemented with beef fat containing either high or low VA levels for 7 weeks. An adapted modified oral glucose tolerance test and fat challenge test were performed at 9 weeks of age following implantation of jugular catheters. Impacts on microbial composition were assessed using 16S rRNA gene amplicon sequencing. The HFHC diet containing beef fat rich in VA had a mild insulin sensitizing effect (p < 0.05, slope of curve), increased plasma HDL cholesterol (p < 0.05, +28%), reduced postprandial plasma TG (p < 0.05), and showed protection from HFHC-induced changes to gut microbial composition in LBW pigs as compared to HFHC diet containing standard beef fat. This is the first study to show effects of natural trans fats on gut dysbiosis; further studies are needed to elucidate mechanisms.

Fueling Gut Microbes: A Review of the Interaction between Diet, Exercise, and the Gut Microbiota in Athletes

The athlete's goal is to optimize their performance. Towards this end, nutrition has been used to improve the health of athletes' brains, bones, muscles, and cardiovascular system. However, recent research suggests that the gut and its resident microbiota may also play a role in athlete health and performance. Therefore, athletes should consider dietary strategies in the context of their potential effects on the gut microbiota, including the impact of sports-centric dietary strategies (e.g., protein supplements, carbohydrate loading) on the gut microbiota as well as the effects of gut-centric dietary strategies (e.g., probiotics, prebiotics) on performance. This review provides an overview of the interaction between diet, exercise, and the gut microbiota, focusing on dietary strategies that may impact both the gut microbiota and athletic performance. Current evidence suggests that the gut microbiota could, in theory, contribute to the effects of dietary intake on athletic performance by influencing microbial metabolite production, gastrointestinal physiology, and immune modulation. Common dietary strategies such as high protein and simple carbohydrate intake, low fiber intake, and food avoidance may adversely impact the gut microbiota and, in turn, performance. Conversely, intake of adequate dietary fiber, a variety of protein sources, and emphasis on unsaturated fats, especially omega-3 (ɷ-3) fatty acids, in addition to consumption of prebiotics, probiotics, and synbiotics, have shown promising results in optimizing athlete health and performance. Ultimately, while this is an emerging and promising area of research, more studies are needed that incorporate, control, and manipulate all 3 of these elements (i.e., diet, exercise, and gut microbiome) to provide recommendations for athletes on how to "fuel their microbes."

Gut Microbiome Diversity and Composition Are Associated with Habitual Dairy Intakes: A Cross-Sectional Study in Men

BACKGROUND

At a population level, the relation between dairy consumption and gut microbiome composition is poorly understood.

OBJECTIVES

We sought to study the cross-sectional associations between individual dairy foods (i.e., milk, yogurt, and cheese), as well as total dairy intake, and the gut microbiome composition in a large, representative sample of men living in south-eastern Australia.

METHODS

Data on 474 men (mean ± SD: 64.5 ± 13.5 y old) from the Geelong Osteoporosis Study were used to assess the cross-sectional association between dairy consumption and gut microbiome. Information on dairy intake was self-reported. Men were categorized as consumers and nonconsumers of milk, yogurt, cheese, and high- and low-fat milk. Milk, yogurt, and cheese intakes were summed to calculate the total dairy consumed per day and categorized into either low (<2.5 servings/d) or high (≥2.5 servings/d) total dairy groups. Fecal samples were analyzed using bacterial 16S ribosomal RNA (rRNA) gene sequencing. After assessment of α and β diversity, differential abundance analysis was performed to identify bacterial taxa associated with each of milk, yogurt, and cheese consumption compared with nonconsumption, low compared with high total dairy, and low- compared with high-fat milk consumption. All analyses were adjusted for potential confounders.

RESULTS

α Diversity was not associated with consumption of any of the dairy groups. Differences in β diversity were observed between milk and yogurt consumption compared with nonconsumption. Taxa belonging to the genera Ruminococcaceae UCG-010 and Bifidobacterium showed negative and weak positive associations with milk consumption, respectively. A taxon from the genus Streptococcus was positively associated with yogurt consumption, whereas a taxon from the genus Eisenbergiella was negatively associated with cheese consumption. No specific taxa were associated with low- compared with high-fat milk nor low compared with high total dairy consumption.

CONCLUSIONS

In men, community-level microbiome differences were observed between consumers and nonconsumers of milk and yogurt. Bacterial taxon-level associations were detected with milk, yogurt, and cheese consumption. Total dairy consumption was not associated with any microbiome measures, suggesting that individual dairy foods may have differential roles in shaping the gut microbiome in men.

The interplay between diet, gut microbes, and host epigenetics in health and disease

The mechanisms linking the function of microbes to host health are becoming better defined but are not yet fully understood. One recently explored mechanism involves microbe-mediated alterations in the host epigenome. Consumption of specific dietary components such as fiber, glucosinolates, polyphenols, and dietary fat has a significant impact on gut microbiota composition and function. Microbial metabolism of these dietary components regulates important epigenetic functions that ultimately influences host health. Diet-mediated alterations in the gut microbiome regulate the substrates available for epigenetic modifications like DNA methylation or histone methylation and/or acetylation. In addition, generation of microbial metabolites such as butyrate inhibits the activity of core epigenetic enzymes like histone deacetylases (HDACs). Reciprocally, the host epigenome also influences gut microbial composition. Thus, complex interactions exist between these three factors. This review comprehensively examines the interplay between diet, gut microbes, and host epigenetics in modulating host health. Specifically, the dietary impact on gut microbiota structure and function that in-turn regulates host epigenetics is evaluated in terms of promoting protection from disease development.

Nutrigenomics of Dietary Lipids

Dietary lipids have a major role in nutrition, not only for their fuel value, but also as essential and bioactive nutrients. This narrative review aims to describe the current evidence on nutrigenomic effects of dietary lipids. Firstly, the different chemical and biological properties of fatty acids contained both in plant- and animal-based food are illustrated. A description of lipid bioavailability, bioaccessibility, and lipotoxicity is provided, together with an overview of the modulatory role of lipids as pro- or anti-inflammatory agents. Current findings concerning the metabolic impact of lipids on gene expression, epigenome, and gut microbiome in animal and human studies are summarized. Finally, the effect of the individual’s genetic make-up on lipid metabolism is described. The main goal is to provide an overview about the interaction between dietary lipids and the genome, by identifying and discussing recent scientific evidence, recognizing strengths and weaknesses, to address future investigations and fill the gaps in the current knowledge on metabolic impact of dietary fats on health.

The Microbiota and the Gut-Brain Axis in Controlling Food Intake and Energy Homeostasis

Obesity currently represents a major societal and health challenge worldwide. Its prevalence has reached epidemic proportions and trends continue to rise, reflecting the need for more effective preventive measures. Hypothalamic circuits that control energy homeostasis in response to food intake are interesting targets for body-weight management, for example, through interventions that reinforce the gut-to-brain nutrient signalling, whose malfunction contributes to obesity. Gut microbiota-diet interactions might interfere in nutrient sensing and signalling from the gut to the brain, where the information is processed to control energy homeostasis. This gut microbiota-brain crosstalk is mediated by metabolites, mainly short chain fatty acids, secondary bile acids or amino acids-derived metabolites and subcellular bacterial components. These activate gut-endocrine and/or neural-mediated pathways or pass to systemic circulation and then reach the brain. Feeding time and dietary composition are the main drivers of the gut microbiota structure and function. Therefore, aberrant feeding patterns or unhealthy diets might alter gut microbiota-diet interactions and modify nutrient availability and/or microbial ligands transmitting information from the gut to the brain in response to food intake, thus impairing energy homeostasis. Herein, we update the scientific evidence supporting that gut microbiota is a source of novel dietary and non-dietary biological products that may beneficially regulate gut-to-brain communication and, thus, improve metabolic health. Additionally, we evaluate how the feeding time and dietary composition modulate the gut microbiota and, thereby, the intraluminal availability of these biological products with potential effects on energy homeostasis. The review also identifies knowledge gaps and the advances required to clinically apply microbiome-based strategies to improve the gut-brain axis function and, thus, combat obesity.

Host-microbial interactions in the metabolism of different dietary fats

Although generally presumed to be isocaloric, dietary fats can differ in their energetic contributions and metabolic effects. Here, we show how an explicit consideration of the gut microbiome and its interactions with human physiology can enrich our understanding of dietary fat metabolism. We outline how variable human metabolic responses to different dietary fats, such as altered ileal digestibility or bile acid production, have downstream effects on the gut microbiome that differentially promote energy gain and inflammation. By incorporating host-microbial interactions into energetic models of human nutrition, we can achieve greater insight into the underlying mechanisms of diet-driven metabolic disease.

High-Fat Diets with Differential Fatty Acids Induce Obesity and Perturb Gut Microbiota in Honey Bee

HFD (high-fat diet) induces obesity and metabolic disorders, which is associated with the alteration in gut microbiota profiles. However, the underlying molecular mechanisms of the processes are poorly understood. In this study, we used the simple model organism honey bee to explore how different amounts and types of dietary fats affect the host metabolism and the gut microbiota. Excess dietary fat, especially palm oil, elicited higher weight gain, lower survival rates, hyperglycemic, and fat accumulation in honey bees. However, microbiota-free honey bees reared on high-fat diets did not significantly change their phenotypes. Different fatty acid compositions in palm and soybean oil altered the lipid profiles of the honey bee body. Remarkably, dietary fats regulated lipid metabolism and immune-related gene expression at the transcriptional level. Gene set enrichment analysis showed that biological processes, including transcription factors, insulin secretion, and Toll and Imd signaling pathways, were significantly different in the gut of bees on different dietary fats. Moreover, a high-fat diet increased the relative abundance of Gilliamella, while the level of Bartonella was significantly decreased in palm oil groups. This study establishes a novel honey bee model of studying the crosstalk between dietary fat, gut microbiota, and host metabolism.

Maternal Linoleic Acid Overconsumption Alters Offspring Gut and Adipose Tissue Homeostasis in Young but Not Older Adult Rats

Maternal n-6 polyunsaturated fatty acids (PUFA) consumption during gestation and lactation can predispose offspring to the development of metabolic diseases such as obesity later in life. However, the mechanisms underlying the potential programming effect of n-6 PUFA upon offspring physiology are not yet all established. Herein, we investigated the effects of maternal and weaning linoleic acid (LA)-rich diet interactions on gut intestinal and adipose tissue physiology in young (3-month-old) and older (6-month-old) adult offspring. Pregnant rats were fed a control diet (2% LA) or an LA-rich diet (12% LA) during gestation and lactation. At weaning, offspring were either maintained on the maternal diet or fed the other diet for 3 or 6 months. At 3 months of age, the maternal LA-diet favored low-grade inflammation and greater adiposity, while at 6 months of age, offspring intestinal barrier function, adipose tissue physiology and hepatic conjugated linoleic acids were strongly influenced by the weaning diet. The maternal LA-diet impacted offspring cecal microbiota diversity and composition at 3 months of age, but had only few remnant effects upon cecal microbiota composition at 6 months of age. Our study suggests that perinatal exposure to high LA levels induces a differential metabolic response to weaning diet exposure in adult life. This programming effect of a maternal LA-diet may be related to the alteration of offspring gut microbiota.

The effects of dairy and dairy derivatives on the gut microbiota: a systematic literature review

The effects of dairy and dairy-derived products on the human gut microbiota remains understudied. A systematic literature search was conducted using Medline, CINAHL, Embase, Scopus, and PubMed databases with the aim of collating evidence on the intakes of all types of dairy and their effects on the gut microbiota in adults. Risk of bias was assessed using the Cochrane risk-of-bias tool.The search resulted in 6,592 studies, of which eight randomized controlled trials (RCTs) met pre-determined eligibility criteria for inclusion, consisting of a total of 468 participants. Seven studies assessed the effect of type of dairy (milk, yogurt, and kefir) and dairy derivatives (whey and casein) on the gut microbiota, and one study assessed the effect of the quantity of dairy (high dairy vs low dairy). Three studies showed that dairy types consumed (milk, yogurt, and kefir) increased the abundance of beneficial genera Lactobacillus and Bifidobacterium. One study showed that yogurt reduced the abundance of Bacteroides fragilis, a pathogenic strain. Whey and casein isolates and the quantity of dairy consumed did not prompt changes to the gut microbiota composition. All but one study reported no changes to bacterial diversity in response to dairy interventions and one study reported reduction in bacterial diversity in response to milk intake.In conclusion, the results of this review suggest that dairy products such as milk, yogurt, and kefir may modulate the gut microbiota composition in favor to the host. However, the broader health implications of these findings remain unclear and warrant further studies.

Allergic sensitization to peanuts is enhanced in mice fed a high-fat diet

The incidence of peanut (PN) allergy is on the rise. As peanut allergy rates have continued to climb over the past few decades, obesity rates have increased to record highs, suggesting a link between obesity and the development of peanut allergy. While progress has been made, much remains to be learned about the mechanisms driving the development of allergic immune responses to peanut. Remaining unclear is whether consuming a Western diet, a diet characterized by overeating foods rich in saturated fat, salt, and refined sugars, supports the development of PN allergy. To address this, we fed mice a high fat diet to induce obesity. Once diet-induced obesity was established, mice were exposed to PN flour via the airways using our 4-week inhalation model. Mice were subsequently challenged with PN extract to induce anaphylaxis. Mice fed a high-fat diet developed significantly higher titers of PN-specific IgE, as well as stronger anaphylactic responses, when compared to their low-fat diet fed counterparts. These results suggest that obesity linked to eating a high-fat diet promotes the development of allergic immune responses to PN in mice. Such knowledge is critical to advance our growing understanding of the immunology of PN allergy.

Facility-dependent metabolic phenotype and gut bacterial composition in CD-1 mice from a single vendor: A brief report

Utilization of murine models remains a valuable tool in biomedical research, yet, disease phenotype of mice across studies can vary considerably. With advances in next generation sequencing, it is increasingly recognized that inconsistencies in host phenotype can be attributed, at least in part, to differences in gut bacterial composition. Research with inbred murine strains demonstrates that housing conditions play a significant role in variations of gut bacterial composition, however, few studies have assessed whether observed variation influences host phenotype in response to an intervention. Our study initially sought to examine the effects of a long-term (9-months) dietary intervention (i.e., diets with distinct fatty acid compositions) on the metabolic health, in particular glucose homeostasis, of genetically-outbred male and female CD-1 mice. Yet, mice were shipped from two different husbandry facilities of the same commercial vendor (Cohort A and B, respectively), and we observed throughout the study that diet, sex, and aging differentially influenced the metabolic phenotype of mice depending on their husbandry facility of origin. Examination of the colonic bacteria of mice revealed distinct bacterial compositions, including 23 differentially abundant genera and an enhanced alpha diversity in mice of Cohort B compared to Cohort A. We also observed that a distinct metabolic phenotype was linked with these differentially abundant bacteria and indices of alpha diversity. Our findings support that metabolic phenotypic variation of mice of the same strain but shipped from different husbandry facilities may be influenced by their colonic bacterial community structure. Our work is an important precautionary note for future research of metabolic diseases via mouse models, particularly those that seek to examine factors such diet, sex, and aging.

High-Fat Diet Induced Alteration of Mice Microbiota and the Functional Ability to Utilize Fructooligosaccharide for Ethanol Production

High-fat diet (HFD) leads to enhancement in various parameters of mice like weight, fasting glucose levels, adipose tissue, and also the liver weight in male C57 BL/6 J mice. Additionally, high-fat diet causes severe liver damage with significant increase in the level of aspartate amino transferase (AST) and alanine transaminase (ALT). The variations in microbiota induced by different diet were analyzed by Illumina MiSeq platform with sequencing of 16S ribosomal RNA (rRNA) gene, and QIIME pipeline was used. The population of Proteobacteria was found to be higher in HFD cecum sample as compared to other treatments. Microbiota analysis suggests that phylum Proteobacteria and Firmicutes were found to be higher in high-fat diet groups as compared to mice fed with normal diet (ND). At the genus level, Bacteroides showed higher population in HFD diet. Bacterial strains belonging to Enterobacteriaceae like Escherichia, Klebsiella, and Shigella were also dominant in HFD treatments. Furthermore, we explored the effects of ethanol production in vitro with supplementation of dietary fibers following inoculation of ND and HFD microbiotas. HFD microbiota of cecum and feces showed high level (P < 0.05) of ethanol production with 2% fructooligosaccharide (FOS) as compared to 2% galactomannan. Microbial fermentation also generated short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate. High levels (P < 0.05) of propionate were found after fermentation of FOS with HFD cecum and feces microbiota. The present study highlights the HFD-induced population of phylum Proteobacteria and genus Bacteroides for ethanol production using FOS as a dietary supplement, and these findings may imply on the harmful effect of HFD even at the microbiota level.

The influence of the gut microbiome on obesity

Obesity is a disease with multiple environmental and genetic factors, which when combined contribute to the maintenance of an elevated body weight, thereby reducing long-term success of weight loss. The human gut microbiome is becoming a new potential contributor to obesity. Specifically, gut bacteria and their metabolites are known to affect dysbiosis, metabolism, endotoxemia, and inflammation. Many environmental and lifestyle factors can alter the gut microbiota affecting obesity. Potential therapies to alter the gut microbiota include supplementation with probiotic organisms and the use of fecal microbiota transplantation. This review will examine the growing evidence supporting the mechanisms with which the human gut microbiota may influence obesity, various influences on the microbiota, and potential therapies.

Gastrointestinal Disorders and Metabolic Syndrome: Dysbiosis as a Key Link and Common Bioactive Dietary Components Useful for their Treatment

Gastrointestinal (GI) diseases, which include gastrointestinal reflux disease, gastric ulceration, inflammatory bowel disease, and other functional GI disorders, have become prevalent in a large part of the world population. Metabolic syndrome (MS) is cluster of disorders including obesity, hyperglycemia, hyperlipidemia, and hypertension, and is associated with high rate of morbidity and mortality. Gut dysbiosis is one of the contributing factors to the pathogenesis of both GI disorder and MS, and restoration of normal flora can provide a potential protective approach in both these conditions. Bioactive dietary components are known to play a significant role in the maintenance of health and wellness, as they have the potential to modify risk factors for a large number of serious disorders. Different classes of functional dietary components, such as dietary fibers, probiotics, prebiotics, polyunsaturated fatty acids, polyphenols, and spices, possess positive impacts on human health and can be useful as alternative treatments for GI disorders and metabolic dysregulation, as they can modify the risk factors associated with these pathologies. Their regular intake in sufficient amounts also aids in the restoration of normal intestinal flora, resulting in positive regulation of insulin signaling, metabolic pathways and immune responses, and reduction of low-grade chronic inflammation. This review is designed to focus on the health benefits of bioactive dietary components, with the aim of preventing the development or halting the progression of GI disorders and MS through an improvement of the most important risk factors including gut dysbiosis.

In Vitro Gastrointestinal Digestion of Palm Olein and Palm Stearin-in-Water Emulsions with Different Physical States and Fat Contents

The impacts of lipid physical state and content on lipid digestion behavior were investigated using 4 and 20% palm olein-in-water emulsions (4% PO and 20% PO) and 4 and 20% palm stearin-in-water emulsions (4% PS and 20% PS). The changes of lipid physical state, particle size, and microstructure during gastrointestinal digestion; the free fatty acid (FFA) released in the intestinal phase; and the fatty acid composition of micellar phases were investigated. After gastric digestion, all emulsions underwent flocculation and coalescence, with 20% PS showing the most extensive aggregation. During intestinal digestion, the FFA release rate and level decreased as the lipid content increased from 4 to 20%, with 4% PO presenting the highest digestion rate and extent. Besides, the solid fat in 4% PS and 20% PS decreased and increased the maximum lipid digestibility, respectively. These results highlighted the combined roles of lipid physical state and content in modulating dietary lipid digestion.

Adolescent dietary manipulations differentially affect gut microbiota composition and amygdala neuroimmune gene expression in male mice in adulthood

Adolescence is a critical developmental period that is characterised by growth spurts and specific neurobiological, neuroimmune and behavioural changes. In tandem the gut microbiota, which is a key player in the regulation of health and disease, is shaped during this time period. Diet is one of the most important regulators of microbiota composition. Thus, we hypothesised that dietary disturbances of the microbiota during this critical time window result in long-lasting changes in immunity, brain and behaviour. C57BL/6 male mice were exposed to either high fat diet or cafeteria diet during the adolescent period from postnatal day 28 to 49 and were tested for anxiety-related and social behaviour in adulthood. Our results show long-lasting effects of dietary interventions during the adolescent period on microbiota composition and the expression of genes related to neuroinflammation or neurotransmission. Interestingly, changes in myelination-related gene expression in the prefrontal cortex following high fat diet exposure were also observed. However, these effects did not translate into overt behavioural changes in adulthood. Taken together, these data highlight the importance of diet-microbiota interactions during the adolescent period in shaping specific outputs of the microbiota-gut-brain axis in later life.

A Humanized Diet Profile May Facilitate Colonization and Immune Stimulation in Human Microbiota-Colonized Mice

BACKGROUND

In spite of the importance of the use of gnotobiotic mice for human fecal transfer, colonization efficiency and immune stimulation after human microbiota inoculation in mice are poorly studied compared to mouse microbiota inoculation. We tested the colonization efficiency and immune responses in mice bred for one additional generation after inoculating the parent generation with either a human (HM) or a mouse microbiota (MM). Furthermore, we tested if colonization efficiency and immune stimulation could be improved in HM-colonized mice by dietary approaches: if these were fed a diet closer to the human diet either in its sources of animal fat and protein [the "animal source" (AS) diet] or in its proportions of macronutrients from the normal sources of a mouse diet [the "human profile" (HP) diet].

RESULTS

Although significantly lower in mice with a human microbiota (30-40% vs. 61-70%) the colonization efficiency was significantly higher in HM mice fed the HP diet (40%), and in MM mice fed AS (70%). The microbiota of mice fed HP was comparable to the microbiota of mice fed a standard rodent chow, while the microbiota of mice fed the animal source diet (AS) clustered separately. Mice inoculated with mouse fecal matter had significantly more CD4+ T cells and Cd4 expression and significantly fewer regulatory T cells (Tregs) and FoxP3 expression than human microbiota inoculated mice, but cell proportions differences were mostly apparent between mice fed the AS diet. Mice fed the HP diet had significantly higher expression of Cd8a.

CONCLUSION

It is concluded that a diet with a humanized profile could support the establishment of a human microbiota in mice, which will, however, still elicit a lower colonization efficiency compared to mice inoculated with a mouse microbiota.

Fatty Acid Diets: Regulation of Gut Microbiota Composition and Obesity and Its Related Metabolic Dysbiosis

Long-term high-fat dietary intake plays a crucial role in the composition of gut microbiota in animal models and human subjects, which affect directly short-chain fatty acid (SCFA) production and host health. This review aims to highlight the interplay of fatty acid (FA) intake and gut microbiota composition and its interaction with hosts in health promotion and obesity prevention and its related metabolic dysbiosis. The abundance of the Bacteroidetes/Firmicutes ratio, as Actinobacteria and Proteobacteria species are associated with increased SCFA production, reported high-fat diet rich in medium-chain fatty acids (MCFAs), monounsaturated fatty acids (MUFAs), and n-3 polyunsaturated fatty acids (PUFAs) as well as low-fat diets rich in long-chain fatty acids (LCFAs). SCFAs play a key role in health promotion and prevention and, reduction and reversion of metabolic syndromes in the host. Furthermore, in this review, we discussed the type of fatty acids and their amount, including the administration time and their interplay with gut microbiota and its results about health or several metabolic dysbioses undergone by hosts.

Different Sources of High Fat Diet Induces Marked Changes in Gut Microbiota of Nursery Pigs

Fat is one of the most important nutrients which provides concentrated energy and essential fatty acids. High fat diet markedly changes the gut microbial composition in mammals, whereas little is known about the impact of fat type on gut microbiome. This study was to evaluate the effects of fat sources on intestinal microbiota of nursery pigs. Eighteen pigs (28 days of age, 8.13 ± 0.10 kg BW) were housed individually (n = 6 per treatment) and allotted to three treatments based on a randomized complete block design. Pigs were fed basal diets with three different fat sources: 6.0% soybean oil (SBO), 6.0% palm oil (PO), and 7.5% encapsulated palm oil (EPO, contains 80% palm oil) respectively. Pigs were euthanized after 28 days of ad libitum feeding, and the digesta in the distal duodenum, jejunum, ileum, cecum and colon of each pig were obtained for microbial composition analysis. Correlation analyses were also performed between microbial composition with nutrients digestibility or growth performance. The results showed that pigs fed PO had marked changes in the bacteria community composition with increasing the richness and diversity in duodenum and jejunum (P < 0.05). Increased abundances of Proteobacteria in duodenum, jejunum and cecum, and decreased abundance of Firmicutes in jejunum were observed in pigs fed PO compared to SBO and EPO. Pigs fed EPO decreased abundances of Proteobacteria in duodenum and jejunum, and increased abundance of Firmicutes compared to pigs fed PO, and was similar to pigs fed SBO. The microbial changes (genus) had significant negative correlation with the fat digestibility. These results indicate that palm oil supplementation in nursery pig diet alters the gut microbial composition, with the most significant changes observed in small intestine. Encapsulation of palm oil, which helps increase the digestibility of palm oil, have beneficial effect on the microbial disturbance caused by palm oil supplementation. Our findings provide a better understanding of how different fat types influence microbial composition in different parts of the intestinal tract and the correlation between bacteria composition and nutrients digestibility, which may provide a new perspective for the rational application of fat in diet.

Intersection of the Gut Microbiome and Circadian Rhythms in Metabolism

The gut microbiome and circadian rhythms (CRs) both exhibit unique influence on mammalian hosts and have been implicated in the context of many diseases, particularly metabolic disorders. It has become increasingly apparent that these systems also interact closely to alter host physiology and metabolism. However, the mechanisms that underlie these observations remain largely unknown. Recent findings have implicated microbially derived mediators as potential signals between the gut microbiome and host circadian clocks; two specific mediators are discussed in this review: short-chain fatty acids (SCFAs) and bile acids (BAs). Key gaps in knowledge and major challenges that remain in the circadian and microbiome fields are also discussed, including animal versus human models and the need for precise timed sample collection.

Colonic bacterial composition is sex-specific in aged CD-1 mice fed diets varying in fat quality

Evidence suggests that sex influences the effect of diet on the gut bacterial composition, yet, no studies have been performed assessing dietary fatty acid composition (i.e., fat quality) in this context. This study examined the effect of dietary fat quality on colonic bacterial composition in an aged, genetically-diverse mouse population. CD-1 mice were fed isoenergetic diets consisting of (1) control fat (CO; "Western-style" fat blend), (2) CO supplemented with 30% fish oil, (3) CO supplemented with 30% dairy fat, or (4) CO supplemented with 30% echium oil. Fecal samples were collected at mid-life and aged (reproductively senescent) time points. Overall, the abundance of Bacteroidetes was greater in mice fed echium oil compared to mice fed the control fat. Examination of colonic bacterial relative abundance also revealed sex differences, with 73 bacterial taxa being differentially expressed in males and females. Notably, results showed a strong interactive effect among the diet, sex, and age of mice which influenced colonic bacterial relative abundance and alpha diversity. In males, supplementation of the diet with dairy fat or echium oil caused the abundance of Bacteroidetes and Bacteroides to change with age. Additionally, supplementation of the diet with fish oil induced sex-dependent changes in the alpha diversity of aged mice compared to mid-life. This work supports that sex is a critical factor in colonic bacterial composition of an aged, genetically-heterogenous population. Moreover, this study establishes that the effectiveness of dietary interventions for health maintenance and disease prevention via direct or indirect manipulation of the gut microbiota is likely dependent on an individual's sex, age, and genetic background.