Oxidative stress plays a major role in the pathogenesis of diabetes mellitus, which further exacerbates damage of cardiac, hepatic and other tissues. We have recently reported that Zn supplementation beneficially modulates hyperglycaemia and hypoinsulinaemia, with attendant reduction of associated metabolic abnormalities in diabetic rats. The present study assessed the potential of Zn supplementation in modulating oxidative stress and cardioprotective effects in diabetic rats. Diabetes was induced in Wistar rats with streptozotocin, and groups of diabetic rats were treated with 5- and 10-fold dietary Zn interventions (0·19 and 0·38 g Zn/kg diet) for 6 weeks. The markers of oxidative stress, antioxidant enzyme activities and concentrations of antioxidant molecules, lipid profile, and expressions of fibrosis and pro-apoptotic factors in the cardiac tissue were particularly assessed. Supplemental Zn showed significant attenuation of diabetes-induced oxidative stress in terms of altered antioxidant enzyme activities and increased the concentrations of antioxidant molecules. Hypercholesterolaemia and hyperlipidaemia were also significantly countered by Zn supplementation. Along with attenuated oxidative stress, Zn supplementation also showed significant cardioprotective effects by altering the mRNA expressions of fibrosis and pro-apoptotic factors (by >50 %). The expression of lipid oxidative marker 4-hydroxy-2-nonenal (4-HNE) protein in cardiac tissue of diabetic animals was rectified (68 %) by Zn supplementation. Elevated cardiac and hepatic markers in circulation and pathological abnormalities in cardiac and hepatic tissue architecture of diabetic animals were ameliorated by dietary Zn intervention. The present study indicates that Zn supplementation can attenuate diabetes-induced oxidative stress in circulation as well as in cardiac and hepatic tissues.

Branched-chain amino acids (BCAA) have been clearly demonstrated to have anabolic effects on muscle protein synthesis. However, little is known about their roles in the regulation of net AA fluxes across skeletal muscle in vivo. This study was aimed to investigate the effect and related mechanisms of dietary supplementation of BCAA on muscle net amino acid (AA) fluxes using the hindlimb flux model. In all fourteen 4-week-old barrows were fed reduced-protein diets with or without supplemental BCAA for 28 d. Pigs were implanted with carotid arterial, femoral arterial and venous catheters, and fed once hourly with intraarterial infusion of p-amino hippurate. Arterial and venous plasma and muscle samples were obtained for the measurement of AA, branched-chain α-keto acids (BCKA) and 3-methylhistidine (3-MH). Metabolomes of venous plasma were determined by HPLC-quadrupole time-of-flight-MS. BCAA-supplemented group showed elevated muscle net fluxes of total essential AA, non-essential AA and AA. As for individual AA, muscle net fluxes of each BCAA and their metabolites (alanine, glutamate and glutamine), along with those of histidine, methionine and several functional non-essential AA (glycine, proline and serine), were increased by BCAA supplementation. The elevated muscle net AA fluxes were associated with the increase in arterial and intramuscular concentrations of BCAA and venous metabolites including BCKA and free fatty acids, and were also related to the decrease in the intramuscular concentration of 3-MH. Correlation analysis indicated that muscle net AA fluxes are highly and positively correlated with arterial BCAA concentrations and muscle net BCKA production. In conclusion, supplementing BCAA to reduced-protein diet increases the arterial concentrations and intramuscular catabolism of BCAA, both of which would contribute to an increase of muscle net AA fluxes in young pigs.

Hyperlipidaemia is a major cause of atherosclerosis and related CVD and can be prevented with natural substances. Previously, we reported that a novel Bacillus-fermented green tea (FGT) exerts anti-obesity and hypolipidaemic effects. This study further investigated the hypotriglyceridaemic and anti-obesogenic effects of FGT and its underlying mechanisms. FGT effectively inhibited pancreatic lipase activity in vitro (IC50, 0·48 mg/ml) and ameliorated postprandial lipaemia in rats (26 % reduction with 500 mg/kg FGT). In hypertriglyceridaemic hamsters, FGT administration significantly reduced plasma TAG levels. In mice, FGT administration (500 mg/kg) for 2 weeks augmented energy expenditure by 22 % through the induction of plasma serotonin, a neurotransmitter that modulates energy expenditure and mRNA expressions of lipid metabolism genes in peripheral tissues. Analysis of the gut microbiota showed that FGT reduced the proportion of the phylum Firmicutes in hamsters, which could further contribute to its anti-obesity effects. Collectively, these data demonstrate that FGT decreases plasma TAG levels via multiple mechanisms including inhibition of pancreatic lipase, augmentation of energy expenditure, induction of serotonin secretion and alteration of gut microbiota. These results suggest that FGT may be a useful natural agent for preventing hypertriglyceridaemia and obesity.

Steatosis can sensitise the liver to various challenges and favour the development of non-alcoholic fatty liver disease (NAFLD). In this context, fructose feeding promotes endotoxin translocation from the gut, contributing to disease progression via an inflammatory process. Citrulline is protective against fructose-induced NAFLD; we hypothesised that this property might be related to its anti-inflammatory and antioxidative action against endotoxin-induced hepatic injuries. This hypothesis was evaluated in a model of perfused liver isolated from NAFLD rats. Male Sprague–Dawley rats (n 30) were fed either a standard rodent chow or a 60 % fructose diet alone, or supplemented with citrulline (1 g/kg per d) for 4 weeks. After an evaluation of their metabolic status, fasted rats received an intraperitoneal injection of lipopolysaccharide (LPS) (2·5 mg/kg). After 1 h, the livers were isolated and perfused for 1 h to study liver function and metabolism, inflammation and oxidative status. In vivo, citrulline significantly decreased dyslipidaemia induced by a high-fructose diet and insulin resistance. In the isolated perfused rat livers, endotoxaemia resulted in higher cytolysis (alanine aminotransferase release) and higher inflammation (Toll-like receptor 4) in livers of fructose-fed rats, and it was prevented by citrulline supplementation. Oxidative stress and antioxidative defences were similar in all three groups. Amino acid exchanges and metabolism (ammonia and urea release) were only slightly different between the three groups. In this context of mild steatosis, our results suggest that fructose-induced NAFLD leads to an increased hepatic sensitivity to LPS-induced inflammation. Citrulline-induced restriction of the inflammatory process may thus contribute to the prevention of NAFLD.

Strategies for preventing Fe deficiency include Fe supplementation and Fe fortification of foods. The absorption, metabolism and chemical characteristics of Fe multi-amino acid chelate (IMAAC) are not known. Absorption of IMAAC was compared with FeSO4 in Fe-depleted mice and in vitro chemical studies of the Fe supplement was performed in HuTu 80 cells. Hb repletion study was carried out in Fe-deficient CD1 mice that were fed for 10 d a diet supplemented with ferrous IMAAC or FeSO4. A control group of Fe-replete mice was fed a diet with adequate Fe concentrations throughout the study. Tissues were collected from the mice, and the expression of Fe-related genes was determined by quantitative PCR. Ferric reductase and Fe uptake were evaluated in HuTu 80 cells. Supplementation of the diet with FeSO4 or IMAAC significantly increased Hb levels (P<0·001) in Fe-deficient mice from initial 93·9 (SD 10·8) or 116·2 (SD 9·1) to 191 (SD 0·7) or 200 (SD 0·5) g/l, respectively. Initial and final Hb for the Fe-deficient control group were 87·4 (SD 6·7) and 111 (SD 11·7) g/l, respectively. Furthermore, the liver non-haem Fe of both supplement groups increased significantly (P<0·001). IMAAC was more effective at restoring Fe in the spleen compared with FeSO4 (P<0·005). Gene expression showed the IMAAC supplement absorption is regulated by the body’s Fe status as it significantly up-regulated hepcidin (P<0·001) and down-regulated duodenal cytochrome b mRNA (P<0·005), similar to the effects seen with FeSO4. A significant proportion of Fe in IMAAC is reduced by ascorbic acid. Fe absorption in mice and cells was similar for both IMAAC and FeSO4 and both compounds induce and regulate Fe metabolism genes similarly in the maintenance of homeostasis in mice.

The aim of this study was to elucidate the relationship between the urinary metabolic fingerprint and the effects of cocoa and cocoa fibre on body weight, hormone metabolism, intestinal immunity and microbiota composition. To this effect, Wistar rats were fed, for 3 weeks, a diet containing 10 % cocoa (C10) or two other diets with same the proportion of fibres: one based on cocoa fibre (CF) and another containing inulin as a reference (REF) diet. The rats’ 24 h urine samples were analysed by an untargeted 1H NMR spectroscopy-based metabonomic approach. Concentrations of faecal IgA and plasma metabolic hormones were also quantified. The C10 diet decreased the intestinal IgA, plasma glucagon-like peptide-1 and glucagon concentrations and increased ghrelin levels compared with those in the REF group. Clear differences were observed between the metabolic profiles from the C10 group and those from the CF group. Urine metabolites derived from cocoa correlated with the cocoa effects on body weight, immunity and the gut microbiota. Overall, cocoa intake alters the host and bacterial metabolism concerning energy and amino acid pathways, leading to a metabolic signature that can be used as a marker for consumption. This metabolic profile correlates with body weight, metabolic hormones, intestinal immunity and microbiota composition.

The purpose of this study was to investigate the effects of 8-week green tea extract (GTE) supplementation on promoting postexercise muscle glycogen resynthesis and systemic energy substrate utilisation in young college students. A total of eight healthy male participants (age: 22·0 (se 1·0) years, BMI: 24·2 (se 0·7) kg/m2, VO2max: 43·2 (se 2·4) ml/kg per min) participated in this study. GTE (500 mg/d for 8 weeks) was compared with placebo in participants in a double-blind/placebo-controlled and crossover study design with an 8-week washout period. Thereafter, all participants performed a 60-min cycling exercise (75 % VO2max) and consumed a carbohydrate-enriched meal immediately after exercise. Vastus lateralis muscle samples were collected immediately (0 h) and 3 h after exercise, and blood and gaseous samples were collected during the 3-h postexercise recovery period. An 8-week oral GTE supplementation had no effects on further promoting muscle glycogen resynthesis in exercised human skeletal muscle, but the exercise-induced muscle GLUT type 4 (GLUT4) protein content was greater in the GTE supplementation trial (P<0·05). We observed that, during the postexercise recovery period, GTE supplementation elicited an increase in energy reliance on fat oxidation compared with the placebo trial (P<0·05), although there were no differences in blood glucose and insulin responses between the two trials. In summary, 8-week oral GTE supplementation increases postexercise systemic fat oxidation and exercise-induced muscle GLUT4 protein content in response to an acute bout of endurance exercise. However, GTE supplementation has no further benefit on promoting muscle glycogen resynthesis during the postexercise period.

Metabolic diversity leads to differences in nutrient requirements and responses to diet and medication between individuals. Using the concept of metabotyping – that is, grouping metabolically similar individuals – tailored and more efficient recommendations may be achieved. The aim of this study was to review the current literature on metabotyping and to explore its potential for better targeted dietary intervention in subjects with and without metabolic diseases. A comprehensive literature search was performed in PubMed, Google and Google Scholar to find relevant articles on metabotyping in humans including healthy individuals, population-based samples and patients with chronic metabolic diseases. A total of thirty-four research articles on human studies were identified, which established more homogeneous subgroups of individuals using statistical methods for analysing metabolic data. Differences between studies were found with respect to the samples/populations studied, the clustering variables used, the statistical methods applied and the metabotypes defined. According to the number and type of the selected clustering variables, the definitions of metabotypes differed substantially; they ranged between general fasting metabotypes, more specific fasting parameter subgroups like plasma lipoprotein or fatty acid clusters and response groups to defined meal challenges or dietary interventions. This demonstrates that the term ‘metabotype’ has a subjective usage, calling for a formalised definition. In conclusion, this literature review shows that metabotyping can help identify subgroups of individuals responding differently to defined nutritional interventions. Targeted recommendations may be given at such metabotype group levels. Future studies should develop and validate definitions of generally valid metabotypes by exploiting the increasingly available metabolomics data sets.

Tools, called ‘diet/dietary quality indices’, evaluate the level of adherence to a specified pattern or a set of recommendations in populations. Yet, there are no review studies providing unanimous comprehensive results of dietary indices on obesity. We reviewed observational studies, focusing on the association of diet quality indices with general obesity or abdominal obesity in adults. We systematically conducted a search in all English language publications available on MEDLINE, ISI Web of Science and Embase between January 1990 and January 2016. Among the wide variety of indices and weight-derived variables, studies with dietary-guideline-based indices and mean changes for weight gain or OR for general obesity and abdominal obesity were selected. From a total of 479 articles, thirty-four studies were selected for the current review, ten of which had prospective designs and twenty-six had cross-sectional designs. Associations of weight status with the original Healthy Eating Index (HEI) and other versions of the HEI including alternative HEI, HEI-2005 and HEI-05 were examined in thirteen studies, with ten studies revealing significant associations. The HEI was a better general obesity predictor in men than in women. Diet scores lacked efficacy in assessing overall diet quality and demonstrated no significant findings in developing countries, in comparison with US populations. In addition, indices based on dietary diversity scores were directly associated with weight gain. Despite the insufficient evidence to draw definitive conclusions about the relation between dietary indices and obesity, HEI was found to be inversely associated with obesity and diversity-based indices were positively associated with obesity.

Oestrogen and n-3 PUFA, especially EPA and DHA, have been reported to have beneficial effects on bone loss. Thus, the purpose of the present study was to investigate the synergistic bone-protective mechanism of combined treatments of EPA+DHA supplementation and oestrogen injection in ovariectomised rats. Rats were fed a modified American Institute of Nutrition-93G diet with 0 %, 1 % or 2 % n-3 PUFA (EPA+DHA) relative to the total energy intake for 12 weeks. Rats were surgically ovariectomised at week 8, and after a 1-week recovery period rats were injected with either 17β-oestradiol-3-benzoate (E2) or maize oil for the last 3 weeks. Combined use of n-3 PUFA and E2 synergistically increased femoral cortical bone volume, bone mineral content and the bone expression of runt-related transcription factor 2 (RUNX2), but decreased the bone expression of IL-1β. Both n-3 PUFA and E2 decreased the bone expressions of IL-7, TNF-α and PPAR-γ, and increased the bone expression of oestrogen receptor-α. n-3 PUFA in the presence of E2 and E2 alone significantly decreased the bone expressions of IL-1β and IL-6 and increased the bone expression of RUNX2. E2 significantly decreased the serum levels of bone turnover markers and the bone expression of receptor activator of NF-κB ligand, but decreased the bone expression of osteoprotegerin. The combined use of n-3 PUFA and E2 exerted synergistic bone-protective efficacy through up-regulation of RUNX2, an essential transcription factor for bone formation, as well as the suppression of bone-resorbing cytokine IL-1β.

Ingestion of collagen peptide (CP) elicits beneficial effects on the body, including improvement in blood lipid profiles, but the underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of CP ingestion on the liver, which controls lipid metabolism in the body. Male BALB/cCrSlc mice were bred with the AIN-93M diet containing 14 % casein or the AIN-93M-based low-protein diet containing 10 % casein or a diet containing 6 % casein+4 % CP for 10 weeks (n 12/group). Total, free and esterified cholesterol levels in the blood decreased in the CP group. DNA microarray analysis of the liver revealed that expressions of genes related to lipid metabolic processes such as the PPAR signalling pathway and fatty acid metabolism increased in the CP group compared with the 10 % casein group. The expressions of several genes involved in steroid metabolic process, including Cyp7a1 and Cyp8b1, were decreased, despite being targets of transcriptional regulation by PPAR. These data suggest that lipid metabolism in the liver is altered by CP ingestion, and the decrease in blood cholesterol levels in the CP group is not due to enhancement of the steroid metabolic process. On the other hand, expressions of genes related to the unfolded protein response (UPR) significantly decreased at the mRNA level, suggesting that CP ingestion lowers endoplasmic reticulum stress. Indeed, protein levels of phosphorylated inositol-requiring enzyme 1 decreased after CP ingestion. Taken together, CP affects the broader pathways in the liver – not only lipid metabolism but also UPR.

Although beneficial effects have been attributed to PUFA supplementation in high-yielding dairy cows, diets rich in PUFA may also increase oxidative stress in tissues such as the liver. To fully exploit the health benefits of PUFA, we believe that the addition of natural antioxidants could help in preventing oxidative damage. Using an in vitro precision-cut liver slices (PCLS) tissue culture system, we investigated the effects of different linoleic acid (LA, n-6):α-linolenic acid (ALA, n-3) ratios (LA:ALA ratio of 4, LA:ALA ratio of 15 and LA:ALA ratio of 25) in the presence or absence of the antioxidant enterolactone (ENL) on (1) the mRNA abundance of genes with key roles in hepatic lipid metabolism, oxidative stress response and inflammatory processes, (2) oxidative damages to lipids and proteins and (3) superoxide dismutase activity in early-lactating dairy cows. The addition of LA and ALA to PCLS culture media increased oxidative damage to lipids as suggested by higher concentrations of thiobarbituric acid reactive substances and increased the expression of nuclear factor erythroid 2-related factor 2 target genes. The addition of ENL was effective in preventing lipid peroxidation caused by LA and ALA. Transcript abundance of sterol regulatory element-binding transcription factor 1 and its lipogenic target genes acetyl-CoA carboxylase α, fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD) was decreased with LA and ALA, whereas ENL decreased FASN and SCD gene expression. Our results show that addition of LA and ALA to PCLS culture media lowers hepatic lipogenic gene expression and increases oxidative damages to lipids. On the other hand, addition of ENL prevents oxidative damages provoked by these PUFA.

A growing body of evidence suggests that capsaicin ingestion may lead to desirable metabolic outcomes; however, the results in humans are equivocal. Whether or not benefits may be gained from ingestion of capsaicin via a commercially available meal has not been determined. The objectives of this randomised, cross-over intervention study were to compare the 2 h postprandial effects of a standard commercially prepared meal containing chilli (HOT, 5·82 mg total capsaicinoids) with a similar meal with no chilli (CON, <1·0 mg total capsaicinoids) on resting energy expenditure, plasma insulin, glucose, serum high sensitivity C-reactive protein (hs-CRP) concentrations, core body temperature and forearm microvascular reactivity responses in overweight individuals. A total of thirty-four apparently healthy individuals (sixteen men and eighteen women) between 18 and 50 years of age, with a BMI >25 kg/m2 and a waist circumference >94 cm (men) or 80 cm (women), were studied. Participants had normal glucose tolerance and were accustomed, but were not regular chilli eaters. A paired t test indicated that insulin AUC was smaller following the HOT meal (P=0·002). Similarly, there was a tendency for glucose AUC to be reduced following the HOT meal (P=0·056). No discernable effects of the HOT meal were observed on metabolic rate, core temperature, hs-CRP concentrations and endothelial-dependent microvascular reactivity. The results from this study indicate that a standard restaurant meal containing a relatively small dose of capsaicin delivered via African bird’s eye chilli, which is currently available to the public, results in lower postprandial insulin concentrations in overweight individuals, compared with the same meal without chilli.

Probiotics are known to regulate host immunity by interacting with systemic and mucosal immune cells as well as intestinal epithelial cells. Supplementation with certain probiotics has been reported to be effective against various disorders, including immune-related diseases. However, little is known about the effectiveness of Lactobacillus paracasei GMNL-32 (GMNL-32), Lactobacillus reuteri GMNL-89 (GMNL-89) and L. reuteri GMNL-263 (GMNL-263) in the management of autoimmune diseases, especially systemic lupus erythematosus (SLE). NZB/W F1 mice, which are a lupus-prone animal model, were orally gavaged with GMNL-32, GMNL-89 or GMNL-263 to investigate the effects of these Lactobacillus strains on liver injuries in NZB/W F1 mice. The results thus obtained reveal that supplementary GMNL-32, GMNL-89 or GMNL-263 in NZB/W F1 mice ameliorates hepatic apoptosis and inflammatory indicators, such as matrix metalloproteinase-9 activity and C-reactive protein and inducible nitric oxide synthase expressions. In addition, supplementation with GMNL-32, GMNL-89 or GMNL-263 in NZB/W F1 mice reduced the expressions of hepatic IL-1β, IL-6 and TNF-α proteins by suppressing the mitogen-activated protein kinase and NF-κB signalling pathways. These findings, presented here for the first time, reveal that GMNL-32, GMNL-89 and GMNL-263 mitigate hepatic inflammation and apoptosis in lupus-prone mice and may support an alternative remedy for liver disorders in cases of SLE.

The present study aimed to investigate the effects of maternal dietary butyrate supplementation on energy metabolism and mitochondrial biogenesis in offspring skeletal muscle and the possible mediating mechanisms. Virgin female rats were randomly assigned to either control or butyrate diets (1 % butyrate sodium) throughout gestation and lactation. At the end of lactation (21 d), the offspring were killed by exsanguination from the abdominal aorta under anaesthesia. The results showed that maternal butyrate supplementation throughout gestation and lactation did not affect offspring body weight. However, the protein expressions of G-protein-coupled receptors (GPR) 43 and 41 were significantly enhanced in offspring skeletal muscle of the maternal butyrate-supplemented group. The ATP content, most of mitochondrial DNA-encoded gene expressions, the cytochrome c oxidase subunit 1 and 4 protein contents and the mitochondrial DNA copy number were significantly higher in the butyrate group than in the control group. Meanwhile, the protein expressions of type 1 myosin heavy chain, mitochondrial transcription factor A, PPAR-coactivator-1α (PGC-1α) and uncoupling protein 3 were significantly increased in the gastrocnemius muscle of the treatment group compared with the control group. These results indicate for the first time that maternal butyrate supplementation during the gestation and lactation periods influenced energy metabolism and mitochondrial biogenesis through the GPR and PGC-1α pathways in offspring skeletal muscle at weaning.

To investigate the effects of maternal dietary protein restriction on offspring Fe metabolism, twenty-four second-parity Landrace×Yorkshire sows were randomly allocated to standard-protein (SP) and low-protein (LP) groups. The SP sows were fed diets containing 15 and 18 % crude protein throughout pregnancy and lactation, respectively, whereas the LP sows were subjected to 50 % dietary protein restriction. Offspring birth weight was not affected, but the body weight at weaning (P=0·06) and average daily gain (P=0·01) of the female piglets were significantly decreased. Serum Fe level in the LP piglets was markedly decreased at weaning, especially in males (P=0·03). Serum ferritin level (P=0·08) tended to be lower, yet serum transferrin was greatly higher (P=0·01) in male weaning piglets of the LP group. Duodenal expression of the divalent metal transporter 1 (DMT1) and ferroportin (FPN) was surprisingly reduced (P<0·05) at the level of protein, but not at the mRNA level, in male weaning piglets of the LP group. Male weaning piglets born to the LP sows exhibited higher hepatic hepcidin levels (P=0·09), lower hepatic expression of transferrin (P<0·01) and transferrin receptor 1 (P<0·05) at the level of mRNA. However, no significant differences were observed for hepatic Fe storage, ferritin, transferrin and transferrin receptor 1 protein expression in male weaning piglets of the two groups. These results indicate that maternal protein restriction during pregnancy and lactation influences growth of female offspring at weaning, reduces duodenal expression of Fe transporters (DMT1 and FPN) and decreases serum Fe level in male weaning piglets.

Se is an essential micronutrient for human health, and fluctuations in Se levels and the potential cellular dysfunction associated with it may increase the risk for disease. Although Se has been shown to influence several biological pathways important in health, little is known about the effect of Se on the expression of microRNA (miRNA) molecules regulating these pathways. To explore the potential role of Se-sensitive miRNA in regulating pathways linked with colon cancer, we profiled the expression of 800 miRNA in the CaCo-2 human adenocarcinoma cell line in response to a low-Se (72 h at <40 nm) environment using nCounter direct quantification. These data were then examined using a range of in silico databases to identify experimentally validated miRNA–mRNA interactions and the biological pathways involved. We identified ten Se-sensitive miRNA (hsa-miR-93-5p, hsa-miR-106a-5p, hsa-miR-205-5p, hsa-miR-200c-3p, hsa-miR-99b-5p, hsa-miR-302d-3p, hsa-miR-373-3p, hsa-miR-483-3p, hsa-miR-512-5p and hsa-miR-4454), which regulate 3588 mRNA in key pathways such as the cell cycle, the cellular response to stress, and the canonical Wnt/β-catenin, p53 and ERK/MAPK signalling pathways. Our data show that the effects of low Se on biological pathways may, in part, be due to these ten Se-sensitive miRNA. Dysregulation of the cell cycle and of the stress response pathways due to low Se may influence key genes involved in carcinogenesis.

This study aimed to explore the potential associations of adherence to the Mediterranean diet with gut microbiota characteristics and gastrointestinal symptomatology in an adult population. Other long-term dietary habits (e.g. consumption of snacks and junk food or stimulant intake) were also evaluated in terms of the gut microbiota profile. Participants (n 120) underwent anthropometric, dietary, physical activity and lifestyle evaluation. Adherence to the Mediterranean diet was assessed using a Mediterranean diet score, the MedDietScore, and subjects were classified into three tertiles according to individual adherence scoring. Gut microbiota composition was determined using quantitative PCR and plate-count techniques, and faecal SCFA were analysed using GC. Gastrointestinal symptoms were also evaluated. Participants with a high adherence to the Mediterranean diet had lower Escherichia coli counts (P=0·022), a higher bifidobacteria:E. coli ratio (P=0·025), increased levels and prevalence of Candida albicans (P=0·039 and P=0·050, respectively), greater molar ratio of acetate (P=0·009), higher defaecation frequency (P=0·028) and a more pronounced gastrointestinal symptomatology compared with those reporting low adherence. A lower molar ratio of valerate was also observed in the case of high adherence to the Mediterranean diet compared with the other two tertiles (Pfor trend=0·005). Positive correlations of MedDietScore with gastrointestinal symptoms, faecal moisture, total bacteria, bifidobacteria:E. coli ratio, relative share of Bacteroides, C. albicans and total SCFA, as well as negative associations with cultivable E. coli levels and valerate were indicated. Fast food consumption was characterised by suppressed representation of lactobacilli and butyrate-producing bacteria. In conclusion, our findings support a link between adherence to the Mediterranean diet and gut microbiota characteristics.

The intestine plays key roles in maintaining body arginine (Arg) homoeostasis. Meanwhile, the intestine is very susceptible to reactive oxygen species. In light of this, the study aimed to explore the effects of Arg supplementation on intestinal morphology, Arg transporters and metabolism, and the potential protective mechanism of Arg supplementation in piglets under oxidative stress. A total of thirty-six weaned piglets were randomly allocated to six groups with six replicates and fed a base diet (0·95 % Arg,) or base diet supplemented with 0·8 % and 1·6 % l-Arg for 1 week, respectively. Subsequently, a challenge test was conducted by intraperitoneal injection of diquat, an initiator of radical production, or sterile saline. The whole trial lasted 11 d. The diquat challenge significantly decreased plasma Arg concentration at 6 h after injection (P<0·05), lowered villus height in the jejunum and ileum (P<0·05) as well as villus width and crypt depth in the duodenum, jejunum and ileum (P<0·05). Oxidative stress significantly increased cationic amino acid transporter (CAT)-1, CAT-2 and CAT-3, mRNA levels (P<0·05), decreased arginase II (ARGII) and inducible nitric oxide synthase mRNA levels, and increased TNF-α mRNA level in the jejunum (P<0·05). Supplementation with Arg significantly decreased crypt depth (P<0·05), suppressed CAT-1 mRNA expression induced by diquat (P<0·05), increased ARGII and endothelial nitric oxide synthase mRNA levels (P<0·05), and effectively relieved the TNF-α mRNA expression induced by diquat in the jejunum (P<0·05). It is concluded that oxidative stress decreased Arg bioavailability and increased expression of inflammatory cytokines in the jejunum, and that Arg supplementation has beneficial effects in the jejunum through regulation of the metabolism of Arg and suppression of inflammatory cytokine expression in piglets.

Recently, it has been found that the gut microbiota influences functions of the host brain by affecting monoamine metabolism. The present study focused on the relationship between the gut microbiota and the brain amino acids. Specific pathogen-free (SPF) and germ-free (GF) mice were used as experimental models. Plasma and brain regions were sampled from mice at 7 and 16 weeks of age, and analysed for free d- and l-amino acids, which are believed to affect many physiological functions. At 7 weeks of age, plasma concentrations of d-aspartic acid (d-Asp), l-alanine (l-Ala), l-glutamine (l-Gln) and taurine were higher in SPF mice than in GF mice, but no differences were found at 16 weeks of age. Similar patterns were observed for the concentrations of l-Asp in striatum, cerebral cortex and hippocampus, and l-arginine (l-Arg), l-Ala and l-valine (l-Val) in striatum. In addition, the concentrations of l-Asp, d-Ala, l-histidine, l-isoleucine (l-Ile), l-leucine (l-Leu), l-phenylalanine and l-Val were significantly higher in plasma of SPF mice when compared with those of GF mice. The concentrations of l-Arg, l-Gln, l-Ile and l-Leu were significantly higher in SPF than in GF mice, but those of d-Asp, d-serine and l-serine were higher in some brain regions of GF mice than in those of SPF mice. In conclusion, the concentration of amino acids in the host brain seems to be dependent on presence of the gut microbiota. Amino acid metabolism in the host brain may be modified by manipulating microbiota communities.