Research indicates that green tea extract (GTE) supplementation is beneficial for a range of conditions, including several forms of cancer, CVD and liver diseases; nevertheless, the existing evidence addressing its effects on body composition, oxidative stress and obesity-related hormones is inconclusive. This systematic review and meta-analysis aimed to investigate the effects of GTE supplementation on body composition (body mass (BM), body fat percentage (BFP), fat mass (FM), BMI, waist circumference (WC)), obesity-related hormones (leptin, adiponectin and ghrelin) and oxidative stress (malondialdehyde (MDA) and total antioxidant capacity (TAC)) markers. We searched proper databases, including PubMed/Medline, Scopus and Web of Science, up to July 2022 to recognise published randomised controlled trials (RCT) that investigated the effects of GTE supplementation on the markers mentioned above. A random effects model was used to carry out a meta-analysis. The heterogeneity among the studies was assessed using the I2 index. Among the initial 11 286 studies identified from an electronic database search, fifty-nine studies involving 3802 participants were eligible to be included in this meta-analysis. Pooled effect sizes indicated that BM, BFP, BMI and MDA significantly reduced following GTE supplementation. In addition, GTE supplementation increased adiponectin and TAC, with no effects on FM, leptin and ghrelin. Certainty of evidence across outcomes ranged from low to high. Our results suggest that GTE supplementation can attenuate oxidative stress, BM, BMI and BFP, which are thought to negatively affect human health. Moreover, GTE as a nutraceutical dietary supplement can increase TAC and adiponectin.

Sperm–zona pellucida (ZP) binding is a necessary event for successful fertilization. The aim of this study was to determine the effect of trace minerals such as copper (Cu), manganese (Mn), selenium (Se) and zinc (Zn) on bovine spermatozoa binding to ZP. Sperm viability, functional membrane integrity, acrosomal status (AS), total antioxidant capacity (TAC) and sperm lipid peroxidation (LPO) were also evaluated. For the present study, in vitro fertilization (IVF) medium was supplemented with Cu (0.4 µg/ml Cu), Mn (5 ng/ml Mn), Se (100 ng/ml Se), Zn (0.8 µg/ml Zn), all minerals (Cu+Mn+Se+Zn), or tested without supplement (Control). Considerably more sperm bound to ZP when Cu, Se or Zn were added to the IVF medium, but there were no difference compared with the Control, Mn and Cu+Mn+Se+Zn groups. After 1 h of incubation, viability was increased by the addition of Cu, Mn and Se with respect to the Control but, after 2 h, viability was higher only with the addition of Mn to IVF medium. Functional membrane integrity improved in sperm treated with Cu. Acrosome integrity was higher in sperm treated with Zn after 1 h of incubation. LPO was significantly higher in sperm treated with Cu or Cu+Mn+Se+Zn. The mean TACs of sperm treated with Cu, Mn, Zn or Cu+Mn+Se+Zn were lower than in the Control. In conclusion, the results obtained in the present study determined that the presence of Cu, Se and Zn in the IVF medium increased the number of spermatozoa bound to the ZP, highlighting the importance of these minerals in the fertilization process.

Glutathione (GSH) is considered to play an important role in maintaining the integrity of the small intestine. In piglets, altered mucosal GSH levels might therefore be involved in weaning-induced changes of the small intestinal morphology and barrier function. To test this hypothesis, we aimed to challenge the mucosal GSH redox status during the first 28 days after weaning, by feeding diets containing 5% fresh linseed oil (CON), or 2.5% (OF1) or 5% (OF2) peroxidized linseed oil (peroxide value 225 mEq O2/kg oil) and exploring the effects on gut integrity. Piglets were pair-fed and had a total daily feed allowance of 32 g/kg BW. A fourth treatment included animals that were fed the control diet ad libitum (ACON). Animals were sampled at days 5 and 28 post-weaning. The malondialdehyde (MDA) concentration and GSH redox status (GSH/GSSG Eh) were determined in blood, liver and small intestinal mucosa. Histomorphology of the duodenal and jejunal mucosa was determined, and Ussing chambers were used to assess fluorescein isothiocyanate dextran (FD4) and horseradish peroxidase (HRP) fluxes across the mucosa. Results show that peroxidized linseed oil imposed an oxidative challenge at day 28, but not at day 5 post-weaning. At day 28, increasing levels of dietary peroxides to pair-fed pigs linearly increased MDA levels in duodenal and jejunal mucosa. Moreover, FD4 fluxes were significantly increased in OF1 (+75%) and OF2 (+64%) in the duodenum, and HRP fluxes tended (P=0.099) to show similar differences, as compared to CON. This co-occurred with a significant 11 mV increase of the hepatic GSH/GSSG Eh, potentiated by a significantly increased GSH peroxidase activity for treatments OF1 (+47%) and OF2 (+63%) in liver as compared to CON. Furthermore; duodenal HRP flux significantly correlated with the hepatic glutathione disulphide (GSSG) level (r=0.650), as also observed in the jejunum for hepatic GSSG (r=0.627) and GSH/GSSG Eh (r=0.547). The jejunal permeability was not affected, but FD4 and HRP fluxes significantly correlated with the local GSH (r=0.619; r=0.733) and GSSG (r=0.635; r=0586) levels. Small intestinal histomorphology was not affected by dietary lipid peroxides, nor were there any correlations found with the GSH redox system. To conclude, under oxidative stress conditions, jejunal barrier function is related to the local and hepatic GSH redox system. It is suggested that the hepatic GSH system participates in the elimination of luminal peroxides, and thereby impacts on duodenal barrier function.

This research paper addresses the hypothesis that dietary pioglitazone (PGT), as synthetic and specific ligand for PPAR-γ or walnut meal (WM) as a natural ligand for PPAR-γ, affect plasma metabolites and reduce the oxidative status in high body condition score (BCS) dairy cows (≥4 BCS). Total of 36 multiparous Holstein cows were randomly assigned to one of the dietary treatments: 1- Control (basal diet; CTR), 2- Walnut meal (9·45% walnut meal of DMI; WM), and 3- Pioglitazone (6 mg/kg BW; PGT). The experimental diets were fed from parturition time to 21 d postpartum. Results showed that the PGT supplementation increased dry matter intake (DMI) (22·95 kg/d) compared to the CTR (21·45 kg/d) and WM (21·78 kg/d) groups. Results showed that milk yield and milk composition were not affected by the experimental diets. Body condition score losses tended to be higher in the CTR group compared to the PGT and WM cows. The PGT group had higher plasma insulin compared to the CTR group (11·84 vs. 10·68 mIU/l), and WM cows had intermediate plasma insulin. The PGT cows had lower plasma non esterified fatty acid (NEFA) and tended to have lower β-hydroxy butyric acid (BHBA) than the CTR group. Feeding pioglitazone decreased plasma malondialdehyde (MDA) and increased plasma total antioxidant capacity (TAC) and superoxide dismutase (SOD) compared to the CTR and WM groups. It was concluded that dietary pioglitazone had positive effects on DMI, BCS change, blood metabolites and oxidative status in fresh dairy cows with high pre-calving BCS. The anti-oxidant effects of walnut meal were not supported by the present data.

Cellular oxidative damage is thought to be one of the key mechanisms underlying age-related cognitive impairment in dogs. Several nutritional interventions to limit cognitive decline are reported in the literature. To our knowledge, the association of grape and blueberry extracts has never been tested in aged dogs. Our objective was to evaluate the effect of a polyphenol-rich extract from grape and blueberry (PEGB) on oxidative status and cognitive performances in aged dogs. A total of thirty-five beagle dogs (aged 8·0–14·5 years) were fed a basal diet with PEGB at either 0 parts per million (ppm) (n 11; control), 240 ppm (n 12; PEGB1) or 480 ppm (n 12; PEGB2) for 75 d. To investigate the effects of PEGB supplementation on cognition and oxidative status, a delayed non-matching to position (DNMP) test and RT-PCR on genes involved in oxidative stress were evaluated. The dogs fed PEGB1 showed a higher superoxide dismutase mRNA expression compared with dogs fed PEGB2 (P = 0·042) and with the control group (P = 0·014). Moreover, the dogs fed PEGB2 showed higher nuclear factor-like 2 (Nrf2) mRNA expression compared with the dogs fed PEGB1 (P = 0·027). Concerning the DNMP test, the proportion of dogs showing cognitive improvements relative to their baseline level was significantly higher in dogs fed the PEGB, regardless of the dosage, than in dogs receiving no supplementation (P = 0·030). The results obtained in the DNMP test suggested a potential benefit of the PEGB on working memory. However, this hypothesis should be further investigated to confirm this cognitive effect.

The present study investigated the effects of medium-chain TAG (MCT) on hepatic oxidative damage in weanling piglets with intra-uterine growth retardation (IUGR). At weaning (mean 21 (sd 1·06) d of age), twenty-four IUGR piglets and twenty-four normal-birth weight (NBW) piglets were selected according to their birth weight (BW; IUGR: mean 0·95 (sd 0·04) kg; NBW: mean 1·58 (sd 0·04) kg) and weight at the time of weaning (IUGR: mean 5·26 (sd 0·15) kg; NBW: mean 6·98 (sd 0·19) kg) and fed either a soyabean oil (SO) diet (containing 5 % SO) or a MCT diet (containing 1 % SO and 4 % MCT) for 28 d. IUGR piglets exhibited poor (P< 0·05) growth performance, lower (P< 0·05) metabolic efficiency of hepatic glutathione (GSH) redox cycle, and increased (P< 0·05) levels of reactive oxygen species, apoptosis and necrosis in hepatocytes compared with NBW piglets. The MCT diet increased (P< 0·05) the average daily gain and feed efficiency of piglets during the first 4 weeks after weaning. Furthermore, MCT diet-fed piglets had a higher (P< 0·05) GSH:oxidised glutathione ratio and increased (P< 0·05) activities of glucose-6-phosphate dehydrogenase (G6PD) and GSH reductase. The expression of G6PD was up-regulated (P< 0·05) by the MCT diet irrespective of BW. Moreover, malondialdehyde concentrations in the liver and apoptosis and necrosis levels in hepatocytes were decreased (P< 0·05) by the MCT diet irrespective of BW. These results indicate that MCT might have auxiliary therapeutic potential to attenuate hepatic oxidative damage in IUGR offspring during early life, thus leading to an improvement in the metabolic efficiency of the hepatic GSH redox cycle.

This study evaluated the strategy of supplementing oral micellized natural vitamin E (d-α-tocopherol) to either piglets and/or sows on α-tocopherol concentrations in piglets serum and tissues after weaning. One first experiment tested the influence of the vitamin E supplementation source (natural form in water v. the synthetic form in feed) and dose administered to piglets and/or sows on serum α-tocopherol concentration, α-tocopherol stereoisomer accumulation, antioxidant capacity and immune response of weaned piglets. A second experiment studied the effect of sow source and dose vitamin E supplementation on some of these parameters in piglets. Oral supplementation to sows with natural vitamin E as a micellized form (d-α-tocopherol) at the lowest dose produced a similar concentration of α-tocopherol in serum at days 2, 14 and 28 postpartum to those supplemented with threefold higher dose of the synthetic form in feed. At day 39 of age, neither piglet supplementation source nor dose significantly affected α-tocopherol accumulation in the serum, muscle, subcutaneous fat or liver. Those piglets from sows supplemented with the micellized alcohol form had higher RRR-α-tocopherol stereoisomers (P<0.001) and lower (P<0.001) RRS- RSS- and RSR-α-tocopherol, at day 39 of age than those from sows supplemented with the synthetic form. A predominant importance of sow over piglet vitamin E supplementation was observed on stereoisomer distribution in piglets. Low doses of oral natural vitamin E supplementation to sows or piglets did not increase the oxidative stress of piglets when compared with the use of the synthetic form in feed. Immunoglobulin levels in piglet serum at day 39 were not affected by natural vitamin E supplementation at low doses in drinking water of piglets or sows when compared with the synthetic form in feed. IgA tended to be higher (P=0.145) at day 39 in piglets supplemented with natural vitamin E when compared with those supplemented with the synthetic form. Low doses of oral micellized natural vitamin E supplementation to sows is an interesting feeding strategy, when compared with the use of high doses of the synthetic form in feed, because it results in similar α-tocopherol concentrations, allows a predominant –R stereoisomer distribution in piglets and also maintains their oxidative status in vivo.

Besides its typical role as an amino acid in protein synthesis, methionine is an important intermediate in methylation reactions. In addition, it can also be converted to cysteine and hence plays a role in the defence against oxidative stress. The present study was conducted to investigate further the role of dl-methionine (DLM) and its hydroxy analogue, dl-2-hydroxy-4-methylthiobutanoic acid (DL-HMTBA), on zootechnical performance and oxidative status of broiler chickens. Male broiler chickens were reared on two diets differing in crude protein (CP) content (low-protein, 18·3 % v. high-protein, 23·2 % CP) and were supplemented either with 0·25 % DLM or 0·25 % DL-HMTBA. Reducing the dietary protein content resulted in an impaired body weight gain (P < 0·0001). However, supplementation of DL-HMTBA to the low-protein diet partially alleviated these negative effects (P = 0·0003). This latter phenomenon could be explained by the fact that chickens fed DL-HMTBA-supplemented diets displayed a better antioxidant status as reflected in lower lipid peroxidation probably as a consequence of their higher hepatic concentrations of total and reduced glutathione compared with their DLM counterparts. On the other hand, within the high protein levels, uric acid might be an important antioxidant to explain the lower lipid peroxidation of high-protein DL-HMTBA-supplemented chickens. Hepatic methionine sulfoxide reductase-A gene expression was not significantly affected by the dietary treatments. In conclusion, the present study indicates that there are interactions between dietary protein content and supplementation of methionine analogues with respect to broiler performance and antioxidant status, also suggesting a causal link between these traits.

Cardiovascular risk is determined by the complex interactions between genetic and environmental factors. The apoE genotype represents the most-widely-studied single nucleotide polymorphism in relation to CVD risk, with >3600 publications cited in PubMed. Although originally described as a mediator of lipoprotein metabolism, the lipoprotein-independent functions of apoE are being increasingly recognised, with limited data available on the potential impact of genotype on these metabolic processes. Furthermore, although meta-analyses suggest that apoE4 carriers may have a 40–50% increased CVD risk, the associations reported in individual studies are highly heterogeneous and it is recognised that environmental factors such as smoking status and dietary fat composition influence genotype–phenotype associations. However, information is often derived from observational studies or small intervention trials in which retrospective genotyping of the cohort results in small group sizes in the rarer E2 and E4 subgroups. Either larger well-standardised intervention trials or smaller trials with prospective recruitment according to apoE genotype are needed to fully establish the impact of diet on genotype–CVD associations and to establish the potential of dietary strategies such as reduced total fat, saturated fat, or increased antioxidant intakes to counteract the increased CVD burden in apoE4 carriers.

In ruminants, Co is required for the synthesis of vitamin B12, which in turn is needed for the resynthesis of methionine by methylation of homocysteine and thus, cobalamin deficiency may induce hyperhomocysteinaemia which is brought into context with perturbations of the antioxidative–prooxidative balance. The present study was conducted to explore whether Co deficiency in cattle is also associated with homocysteine-induced disturbances of oxidative status. Co deficiency was induced in cattle by feeding two groups of animals on either a basal maize-silage-based diet that was moderately low in Co (83 μg Co/kg DM), or the same diet supplemented with Co to a total of 200 μg Co/kg DM, for 43 weeks. Co deficiency was apparent from a reduced vitamin B12 status in serum and liver and an accumulation of homocysteine in plasma which was in excess of 4·8 times higher in Co-deprived cattle than in controls. The much increased level of circulating homocysteine did not indicate severe disturbances in antioxidant–prooxidant balance as measured by individual markers of lipid peroxidation, protein oxidation, and the antioxidative defence system. There were no quantitative difference in plasma thiol groups, nor were there significant changes in concentrations of α-tocopherol, microsomal thiobarbituric acid-reactive substances and carbonyl groups in liver. However, there was a trend toward increased plasma carbonyl levels indicating a slight degradation of plasma proteins in the hyperhomocysteinaemic cattle. Analysis of the hepatic catalase (EC 1.11.1.6) activity revealed an 11 % reduction in Co-deficient cattle relative to the controls. These results indicate that long-term moderate Co deficiency may induce a severe accumulation of plasma homocysteine in cattle, but considerable abnormalities in oxidative status failed to appear.