Effect Of Antioxidant Supplementation Research Articles

Mechanical Ventilation Antioxidant Trial.

Many patients each year require prolonged mechanical ventilation. Inflammatory processes may prevent successful weaning, and evidence indicates that mechanical ventilation induces oxidative stress in the diaphragm, resulting in atrophy and contractile dysfunction of diaphragmatic myofibers. Antioxidant supplementation might mitigate the harmful effects of the oxidative stress induced by mechanical ventilation. To test the clinical effectiveness of antioxidant supplementation in reducing the duration of mechanical ventilation. A randomized, prospective, placebo-controlled double-blind design was used to test whether enterally administered antioxidant supplementation would decrease the duration of mechanical ventilation, all-cause mortality, and length of stay in the intensive care unit and hospital. Patients received vitamin C 1000 mg plus vitamin E 1000 IU, vitamin C 1000 mg plus vitamin E 1000 IU plus N-acetylcysteine 400 mg, or placebo solution as a bolus injection via their enteral feeding tube every 8 hours. Clinical and statistically significant differences in duration of mechanical ventilation were seen among the 3 groups (Mantel-Cox log rank statistic = 5.69, df = 1, P = .017). The 3 groups did not differ significantly in all-cause mortality during hospitalization or in the length of stay in the intensive care unit or hospital. Enteral administration of antioxidants is a simple, safe, inexpensive, and effective intervention that decreases the duration of mechanical ventilation in critically ill adults.

Effects of Vitamin E, Selenium and Vitamin C on Various Biomarkers Following Oxidative Stress Caused by Diazinon Exposure in Rainbow Trout

Biochemical parameters are appropriate biomarkers to assess the effects of pesticides on an aquatic ecosystem. Diazinon is an organophosphate pesticide whose metabolism in fish body produces reactive oxygen species that can cause oxidative stress. In this study, Oncorhynchus mykiss fish were allocated into four treatment groups (with three replicates): control; Diazinon (0.1 mg L 1); vitamin C (300 mg kg 1 in diet) plus diazinon (0.1 mg L 1) and vitamin E, selenium (selenium 0.5 & vitamin E 100 mg kg-1 in the diet) plus diazinon (0.1 mg L 1). Blood samples were obtained after two and four weeks and superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (TAC) and malondialdehyde (MDA) were measured. SOD activity was significantly lower in diazinon-exposed fish than in the control group. However, there were no differences between the two supplemented groups and the control group in this regard. CAT activity was significantly higher in all three diazinon-exposed groups compared to the control group. However vitamin E, selenium had the least difference with the control group. Maximum and minimum TAC were observed respectively in fish supplemented with vitamin E, selenium and those only exposed to diazinon. The diazinon group also had the highest MDA levels. The two supplemented groups and the control group had no significant differences in MDA levels. These findings highlighted the antioxidant effects of supplementation with vitamin E, selenium or vitamin C against free radical produced during the metabolism of diazinon. Meanwhile, the combination of vitamin E, selenium had higher antioxidant effects than vitamin C. Moreover, SOD, the first defensive barrier against superoxide radicals and MDA, an index of cellular damage induced by hydroxyl radicals, are the most suitable indicators to assess the effects of diazinon.

Supplementation of Vitamin E and C in the Feed on Color, Cooking Loss and Tenderness of Muscovy Ducks Meat Stored in Room Temperature, Refrigerator and Freezer

Research has been conducted to determine the effectiveness of antioxidant supplementation of vitamin E and C in the feed to meat quality of the Muscovy duck meat stored at room temperature, refrigerator and freezer. Eighty-four Muscovy duck tail males aged 9 weeks maintained for 5 weeks and allocated into 7 treatments with 4 replications and each replication consisted of Muscovy duck 3 heads. Completely Randomized Design was applied, in the which treatments were vitamin E and vitamin C supplementation to the basal feed containing 21% protein and 3100 kcal / kg administered metabolic energy into seven groups namely E0C0: basal feed without Vit E and Vit C, E400: basal feed plus 400 IU of vitamin E, E600: basal feed plus 600 IU of vitamin E, C400: basal feed plus 400 mg / kg feed vitamin C, C600: basal feed plus 600 mg / kg feed as much vitamin C, E200C200: basal feed plus 200 IU vitamin E and 200 mg / kg feed vitamin C, and E300C300: basal feed plus 300 IU of vitamin E and 300 mg / kg feed of vitamin C. The parameters measured were the color of meat that includes the value of L * (lightness), a * (Redness) and b * (yellowness), tenderness and cooking looses. The data obtained and the analysis of variance followed honestly significant difference test.Muscovy duck meat that vitamin E-supplemented feed brightness levels did not differ (P> 0.05) with non-supplemented, otherwise Muscovy duck meat that feed supplemented vitamin C or a combination of vitamin E and C levels of brightness up to 3 days either at room temperature or stored the refrigerator is still high. Supplementation of vitamin E and C was highly significant (P <0.01) against redness (a*) meat stored in different storage means. Muscovy duck meat that feed not supplemented vitamin E and C redness (a*) did not differ (P> 0.05) between the age of 0 hours with that stored in the refrigerator or freezer. B * value of Muscovy duck meat that feed not given vitamin E and C as well as different combinations (P <0.05) with Muscovy duck meat that feed supplemented with vitamin C or a combination of vitamins E and C. The Muscovy duck meat that feed supplemented vitamin E, C or a combination of vitamins E and C if stored at room temperature or refrigerator up to 3 days the value of L* and a* is still high, but the b * low.

Supplementation of Vitamin E and C in the Feed to Meat Quality of Muscovy Ducks Stored in a Temperature Chamber, Refrigerator and Freezer

Research has been conducted to determine the effectiveness of antioxidant supplementation of vitamin E and C in the feed to meat quality of the Muscovy duck meat stored at room temperature, refrigerator and freezer. Eighty-four Muscovy duck tail males aged 9 weeks maintained for 5 weeks and allocated into 7 treatments with 4 replications and each replication consisted of Muscovy duck 3 heads. Completely Randomized Design was applied, in the which treatments were vitamin E and vitamin C supplementation to the basal feed containing 21% protein and 3100 kcal / kg administered metabolic energy into seven groups namely E0C0: basal feed without Vit E and Vit C, E400: basal feed plus 400 IU of vitamin E, E600: basal feed plus 600 IU of vitamin E, C400: basal feed plus 400 mg / kg feed vitamin C, C600: basal feed plus 600 mg / kg feed as much vitamin C, E200C200: basal feed plus 200 IU vitamin E and 200 mg / kg feed vitamin C, and E300C300: basal feed plus 300 IU of vitamin E and 300 mg / kg feed of vitamin C. The parameters measured were the color of meat that includes the value of L * (lightness), a * (Redness) and b * (yellowness), tenderness and cooking looses. The data obtained and the analysis of variance followed honestly significant difference test.Muscovy duck meat that vitamin E-supplemented feed brightness levels did not differ (P> 0.05) with non-supplemented, otherwise Muscovy duck meat that feed supplemented vitamin C or a combination of vitamin E and C levels of brightness up to 3 days either at room temperature or stored the refrigerator is still high. Supplementation of vitamin E and C was highly significant (P <0.01) against redness (a*) meat stored in different storage means. Muscovy duck meat that feed not supplemented vitamin E and C redness (a*) did not differ (P> 0.05) between the age of 0 hours with that stored in the refrigerator or freezer. B * value of Muscovy duck meat that feed not given vitamin E and C as well as different combinations (P <0.05) with Muscovy duck meat that feed supplemented with vitamin C or a combination of vitamins E and C. The Muscovy duck meat that feed supplemented vitamin E, C or a combination of vitamins E and C if stored at room temperature or refrigerator up to 3 days the value of L* and a* is still high, but the b * low.

Antioxidants safeguard telomeres in bold chicks.

Telomeres are sensitive to damage induced by oxidative stress, and thus it is expected that dietary antioxidants may support the maintenance of telomere length in animals, particularly those with a fast rate of life (e.g. fast metabolism, activity and growth). We tested experimentally the effect of antioxidant supplements on telomere length during early development in wild gull chicks with natural individual variations in behaviour pattern and growth rate. Proactive chicks had shorter telomeres than reactive chicks, but the penalty for the bold behaviour pattern was reduced by antioxidant supplementation. Chicks growing faster had longer telomeres during early growth, suggesting that inherited quality supports a fast life history.

Effects of Acai berry supplementation on exercise adaptation of mice

BackgroundDietary antioxidant supplementation is now a matter of debate in sports science. Traditionally, vitamin supplementation has been widely used by athletes, for the purpose of recovering from fatigue or enhancing performance. However, recent research shows conflicting data about the effectiveness of antioxidant supplementation, and some research even indicates antioxidant supplementation inhibits adaptation response to endurance training. The antioxidant used in these studies, however, is only limited to antioxidant vitamins or single type of antioxidant. Since a body of data indicate antioxidants work synergistically, we used whole food Acai berry as antioxidant supplementation.【Method】We divided 32 male ICR mice (7wk old) into four groups, Acai‐fed group (Ac), trained group (Tr), Acai‐fed and trained group (AcTr), and control group (Cn, n = 8 for each group). Ac group and AcTr group were fed normal chow (MF, Oriental Kobo) mixed with freeze‐dried Acai powder (10% in weight, Amazonia) for 6 weeks. Tr group and AcTr group were trained on a treadmill for 60 min/day, 5 days/wk (20 m/min). After 6 weeks of the intervention, mice were sacrificed and citrate synthase activities of the skeletal muscle were measured.【Result and Discussion】There are no differences in exercise performance between Tr and AcTr groups. The citrate synthase activities are higher among trained group (compared with non‐trained groups, p < 0.01), but not in Acai‐fed group (compared with normal chow groups). Therefore, our current data don't support the idea that whole food antioxidant‐rich Acai berry supplementation is beneficial for athletes.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases.

BACKGROUND: Our previous systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review. OBJECTIVES: To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults. METHODS: Search methods: We searched The Cochrane Library, Medline, Embase, Lilacs, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials. Selection criteria: We included all primary and secondary prevention randomized clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Data collection and analysis: Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimize the risk of systematic errors. Trial sequential analyses were conducted to minimize the risk of random errors. Random effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity. MAIN RESULTS: Seventy-eight randomized trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I2- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertribal heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/ 77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/ 29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002). AUTHORS' CONCLUSIONS: We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Effect of vitamin C and vitamin E supplementation on endothelial function: a systematic review and meta-analysis of randomised controlled trials.

Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial function (EF) have reported conflicting results. We aimed to investigate the effects of supplementation with antioxidant vitamins C and E on EF and to explore factors that may provide explanations for the inconsistent results. We searched four databases (MEDLINE, Embase, Cochrane Library and Scopus) from inception until May 2014 for RCT involving adult participants aged ≥18 years who were supplemented with vitamins C and E alone or in combination for more than 2 weeks and reporting changes in EF measured using flow mediated dilation or forearm blood flow. Data were pooled as standardised mean difference (SMD) and analysed using a random-effects model. Significant improvements in EF were observed in trials supplementing with vitamin C alone (500-2000 mg/d) (SMD: 0·25, 95% CI 0·02, 0·49, P=0·043) and vitamin E alone (300-1800 IU/d; 1 IU vitamin E=0·67 mg natural vitamin E) (SMD: 0·48, 95% CI 0·23, 0·72, P=0·0001), whereas co-administration of both vitamins was ineffective (vitamin C: 500-2000 mg/d; vitamin E: 400-1200 IU/d) (SMD: 0·12, 95% CI-0·18, 0·42, P=0·428). The effect of vitamin C supplementation on EF increased significantly with age (β 0·023, 95% CI 0·001, 0·05, P=0·042). There was a significant negative correlation between baseline plasma vitamin E concentration and the effect of vitamin E supplementation on EF (β-0·03, 95% CI-0·06, -0·001, P=0·029). Supplementation with either vitamin C or vitamin E alone improves EF. However, subgroup analysis emphasises the importance of careful characterisation and selection of a population group which may benefit from such supplementation.

Oxidative stress causes imbalance of renal renin angiotensin system (RAS) components and hypertension in obese Zucker rats.

BackgroundOxidative stress plays an important role in the pathogenesis of hypertension, especially in obesity‐related hypertension. The natriuretic and antinatriuretic components of the renal renin angiotensin system (RAS) maintain sodium homeostasis and blood pressure. Here, we test the hypothesis that increased oxidative stress leads to the imbalance of RAS components and hypertension in obese Zucker rats.Methods and ResultsLean and obese rats received vehicle or tempol, a superoxide dismutase mimetic in the drinking water for 4 weeks. Compared with vehicle‐treated lean rats, vehicle‐treated obese rats exhibited higher blood pressure and increased renal oxidative stress, accompanied by increased diuretic and natriuretic responses to AT1R antagonist (Candesartan) and AT2R agonist (CGP‐42112A) and reduced diuretic and natriuretic response to MasR agonist (Ang‐[1 to 7]). Moreover, obese rats had higher ACE, AT1R and AT2R, lower ACE2 and MasR expressions in the kidney. All of the above‐mentioned abnormalities were reversed to some degree by tempol treatment. In primary cultures of renal proximal tubular (RPT) cells from lean and obese rats, tempol treatment also increased AT2R, ACE2, and MasR expressions but decreased AT1R and ACE expressions in obese rats.ConclusionsTaken together, our study indicated that the imbalance of renal RAS components was associated with increased oxidative stress in obese rats. Furthermore, antioxidant treatment with tempol reversed the imbalance of renal RAS components and led to diuresis and natriuresis, which, at least in part, explains the blood pressure‐lowering effect of antioxidant supplementation in obesity‐related hypertension.

Antioxidant Supplementation on Cancer Risk and During Cancer Therapy: An Update

Radiation and some chemotherapeutic agents used in conventional cancer treatment generate reactive oxygen species (ROS), and a high ROS level diminishes cellular antioxidant capacity and leads to apoptosis and cancer cell death. Antioxidant supplements are consumed widely by cancer patients in order to prevent toxic side effects of cancer treatment to normal tissues and organs. However, the effects of antioxidant supplementation in cancer therapy were largely disappointing. There is still no consensus on the efficacy and safety of dietary antioxidant supplementation during conventional cancer therapy. In some studies, antioxidant supplements did not reduce the risk for cancer or prevent tumour growth; at the contrary, these interventions resulted in some cases to be harmful to the patients. Therefore, a guidance on antioxidant supplementation based on large clinical trials is urgently needed in order to obtain the best possible care and to avoid risky treatments for cancer patients.

Does combined antioxidant vitamin supplementation blunt repeated bout effect?

We investigated the effect of antioxidant supplementation on markers of muscle damage, antioxidant status, and delayed onset of muscle soreness (DOMS) after repeated downhill runs. Moderately-trained males (n=22) were randomly assigned to a supplement (S) or placebo (P) group. Capsules (vitamin C:1 000 mg/d; vitamin E: 400 IU/d) were ingested daily for 2 weeks. before the first (1D) and second (2D) downhill runs, and for 2 additional days following each run. Creatine kinase (CK) activity and oxygen radical absorbance capacity (ORAC) were measured pre-exercise and at 0 (immediately), 6, 24 and 48 h post-exercise (POST). DOMS was rated for quadriceps, hamstring, gluteus, gastrocnemius, and tibialis anterior at 0, 24, 48 and 72 h POST. CK at 48 h following 1D remained elevated above pre-exercise only in P (P<0.01). Overall, DOMS of the quadriceps was lower in S (1.1±0.3) than P (2.2±0.5) (P<0.05). At 24 h POST in S, CK was lower (P<0.01) and ORAC was higher (P<0.05) following 2D than 1D. CK and ORAC following 2D were blunted and augmented, respectively, in response to 1D and antioxidant supplementation enhanced this protective effect as indicated by an attenuation of biomarkers of muscle damage and a greater antioxidant capacity observed 24 h POST 2D.

The Dietary Combination of Quercetin and Resveratrol Supplementation May Improve Exercise Tolerance in Young Untrained Males by Modulating IL-6 and NGAL Response

The effect of antioxidant supplementation on exercise performance has not been clearly defined in trained or un-trained individuals. The purpose of this investigation was to test the effects of quercetin-resveratrol combination on plasma anti-inflammatory response and exercise performance in untrained men. After baseline cycling performance testing, the subjects (n=8) were supplemented daily with 500gr quercetin and 500 gr resveratrol for 21 days. The complete blood counts, creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), interleukin-6 (IL-6), Neutrophil gelatinase-associated lipocalin (NGAL) and exercise performance parameters were evaluated at baseline, after 21 days of supplementation and 15 days after the end of the study. The maximal aerobic power (POmax) was increased (19%) in the post-supplementation period compare to baseline and washout period. In the post-supplementation period, the time trial score (TTscore), maximal and average speed significantly increased in the 10 km time trial cycling test compare to the baseline level. Importantly, in response to supplementation, the serum IL-6 and N-GAL levels were upregulated post-supplementation and these levels returned to baseline levels at the end of the washout period. These results suggest that dieatary combination of quercetin and resveretrol may act as a potential tool for enhancing exercise performance by regulation IL-6, NGAL level in untrained men.

Evaluation of serum antioxidants in age-related hearing loss.

Age-related hearing loss (ARHL) has been linked to the shift in the pro-oxidant/antioxidant ratio. Our objectives were to assess serum levels of retinol and zinc among the elderly individuals and to correlate the levels with hearing threshold. Prospective study of apparently healthy individuals aged ≥60 years of age. Participants had complete clinical history, physical examination and pure tone average conducted. Blood samples were collected for determination of serum levels of retinol and zinc. Mann-Whitney U test was used to compare retinol and zinc values. Pearson's correlation test was used to determine the relationship between hearing threshold and serum levels of retinol and zinc. Among 126 elderly participants with mean age 67 ± 2.7 years; the mean pure tone average for air conduction was 29.3 ± 1.6 dBHL while the mean bone conduction was 36.5 ± 1.8 dBHL. The median values of serum retinol and zinc levels in the elderly participants who had hearing loss in the speech frequencies were 52 and 83.3 μg/L, respectively, while among participants with normal hearing threshold, values were 50 and 89.9 μg/L, respectively (p = 0.59 and 0.99, respectively). For the high frequencies, the median value of serum retinol and zinc levels among the elderly participants with normal hearing threshold was 70.3 and 99.9 μg/L, while among those with hearing loss, it was 46.9 and 83.2 μg/L, respectively (p = 0.000 and 0.005, respectively). Serum retinol and zinc levels were significantly lower among elderly with hearing loss involving the high frequencies. This is added evidence to extant literature on the possible role of antioxidants in the development of ARHL and suggests further study on the effect of antioxidants supplementation in the control of ARHL which is presently controversial and inconclusive.

Are antioxidant supplements effective in reducing delayed onset muscle soreness? A systematic review

In recent years, antioxidant supplements have become popular to counter the effects of free radicals and muscle damage symptoms, including delayed onset muscle soreness (DOMS). To conduct a systematic review in different databases to determine the effects of antioxidant supplements on DOMS. We conducted a search in databases; Cochrane, Pubmed, Scopus and SportDiscus and Web of Science (WOS). The words and acronyms used were; Delayed onset muscle soreness, exercise induced muscle damage, DOMS, EIMD, antioxidant and oxidative stress. 54 articles were identified of which 48 were retreived, all in English, 17 related to vitamin C and E, supplements polyphenolic correspond to fourteen, eleven other antioxidant supplements and six to commercial supplements, all of them used to diminish the DOMS and other variables. Both vitamins and commercial supplements have low effectiveness in reducing DOMS, while polyphenols and other antioxidant supplements show moderate to good effectiveness in combating DOMS. However, most of the studies have effectiveness in reducing other symptoms of muscle damage besides helping in the post-exercise recovery.

P3 - Antioxidants and muscle atrophy in colon cancer: beneficial or deleterious effects?

Cancer cachexia is a multifactorial syndrome characterized by an ongoing loss of body weight, mainly due to adipose tissue and skeletal muscle wasting. Muscle atrophy leads to a progressive functional impairment and contributes to a negative impact on patient’s quality of life. Oxidative Stress (OS) seems to play a major role in muscle atrophy since OS markers are increased in plasma and muscles of cancer patients. Thus, supplementing patients with antioxidant may reduce OS and restore muscle mass and function. In this study, we assess the effects of antioxidant supplementation on muscle atrophy in a model of colon 26 tumor-bearing mice (C26-mice). Five-week old Balb/c mice receive a subcutaneous injection of PBS or C26 cancer cells with or without daily supplementation with Allopurinol or Oxynov (50mg/kg and 163mg/kg respectively). Blood and muscles are removed 20–22 days after injection. C26-mice develop cachexia, with a decrease in total body weight, muscular endurance and muscle fibers diameter. Furthermore, injection of C26 induces ubiquitination of muscles proteins, suggesting the enhancement of muscle proteolysis. Contrary to our expectations, supplementation with antioxidants (Allopurinol or Oxynov) doesn’t prevent weight loss and muscle atrophy but induces premature death of mice. C26-mice exhibit systemic oxidative stress markers (i.e. carbonyl proteins and 4-HNE) and show an increase in phosphorylation levels of the redox-dependent kinase, JNK, in the atrophied muscles (i.e. gastrocnemius). Surprisingly, Allopurinol or Oxynov decrease the total antioxidant defenses in plasma but has no effect on C26-induced oxidative damages and JNK phosphorylation. Our results are in agreement with recent reports showing deleterious effects of antioxidants supplementation in lung and prostate cancer. However, such findings require further investigations.

Inhibition of ROS production through mitochondria-targeted antioxidant and mitochondrial uncoupling increases post-thaw sperm viability in yellow catfish

Reactive oxygen species (ROS) are one of the main causes for decreased viability in cryopreserved sperm. Many studies have reported the beneficial effect of antioxidant supplements in freezing media for post-thaw sperm quality. In the present study, we explored two new approaches of ROS inhibition in sperm cryopreservation of yellow catfish, namely mitochondrial-targeted antioxidant and metabolic modulator targeting mitochondrial uncoupling pathways. Our study revealed that addition of MitoQ, a compound designed to deliver ubiquinone into mitochondria, significantly decreased ROS production, as well as lipid peroxidation, and increased post-thaw viability. Similarly, sperm incubated with 2,4-dinitrophenol (DNP), a chemical protonophore that induces mitochondrial uncoupling, also had reduced ROS production, as well as lipid peroxidation, and increased post-thaw sperm viability. Conversely, activation of uncoupling protein (UCP2) by 4-hydroxynonenal (HNE) neither reduced ROS production nor increased post-thaw sperm viability. Our findings indicate that ROS inhibition through mitochondrial-targeted antioxidant or mild mitochondrial uncoupling is beneficial for sperm cryopreservation in yellow catfish. Our study provides novel methods to mitigate oxidative stress induced damage in cryopreserved sperm for future applications.

Don't mess with stress: vitamin supplementation and the role of oxidative stress for aerobic exercise adaptation.

The effect of chronic antioxidant and anti-inflammatory supplementation on the adaptive process to exercise training is an emerging area of research, with training implications that have yet to be elucidated fully. The use of these agents has become more popular amongst athletes and recreationally active individuals, thus the long-term consequence of their chronic use for muscle and cardiovascular adaptation is an important consideration for this population. Usage of these supplements relates to the common belief that exercise-induced inflammation and oxidative stress play a crucial role in muscle soreness and weakness in the hours and days following a strenuous bout of exercise. Hence, anti-inflammatory and antioxidant supplements are used with the expectation that reducing exercise-induced stress in fatigued muscles will reduce soreness and promote quicker recovery.

A functional variant in NKX3.1 associated with prostate cancer risk in the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

NKX3.1 is an androgen-regulated prostate tumor suppressor protein. We previously found that antioxidant administration (N-acetylcysteine) in the Nkx3.1 knockout mouse model promoted prostate epithelial proliferation, suggesting that NKX3.1 activity modifies the effect of antioxidant administration on prostate carcinogenesis. Interestingly, administration of the antioxidant vitamin E significantly increased prostate cancer risk in the Selenium and Vitamin E Cancer Prevention Trial (SELECT), suggesting that our animal experiments may be relevant to humans. To determine whether NKX3.1 played a role in increased human prostate cancer risk associated with antioxidant administration in SELECT, we investigated the joint risk of antioxidant administration and NKX3.1 genotypes previously found to be associated with decreased NKX3.1 mRNA expression (rs11781886) or DNA-binding activity in vitro (rs2228013) in the SELECT biomarker case-cohort substudy (1,866 cases; 3,135 non-cases). Multivariable COX regression models were developed to determine the joint association of NKX3.1 genotypes with administration of vitamin E, selenium, or the combination, compared with placebo. The CC genotype at rs11781886 combined with selenium administration was associated with increased overall prostate cancer risk [HR, 1.676; 95% confidence interval (CI), 1.011-2.777; P = 0.045] and low-grade prostate cancer risk (HR, 1.811; 95% CI, 1.016-3.228; P = 0.0441). Similarly, the rs11781886 minor allele (CC+CT) combined with vitamin E administration was significantly associated with increased prostate cancer risk (HR, 1.450; 95% CI, 1.117-1.882; P = 0.0052). Our results indicate that variation in NKX3.1 expression combined with selenium or vitamin E treatment modifies the risk of prostate cancer. Genetic background may modulate the effects of antioxidant supplementation thought to act as chemoprevention agents.

Antioxidant supplementation for lung disease in cystic fibrosis

Airway infection leads to progressive damage of the lungs in cystic fibrosis and oxidative stress has been implicated in the etiology. Supplementation of antioxidant micronutrients (vitamin E, vitamin C, ß-carotene and selenium) or glutathione may therefore potentially help maintain an oxidant-antioxidant balance. Current literature suggests a relationship between oxidative status and lung function. To synthesize existing knowledge of the effect of antioxidants such as vitamin C, vitamin E, ß-carotene, selenium and glutathione in cystic fibrosis lung disease. The Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register and PubMed were searched using detailed search strategies. We contacted authors of included studies and checked reference lists of these studies for additional, potentially relevant studies.Last search of Cystic Fibrosis Trials Register: 29 August 2013. Randomized controlled studies and quasi-randomized controlled studies of people with cystic fibrosis comparing antioxidants as listed above (individually or in combination) in more than a single administration to placebo or standard care. Two authors independently selected studies, extracted data and assessed the risk of bias in the included studies. We contacted trial investigators to obtain missing information. Primary outcomes are lung function and quality of life; secondary outcomes are oxidative stress, inflammation, nutritional status, days on antibiotics and adverse events during supplementation. If meta-analysed, studies were subgrouped according to method of administration and the duration of supplementation. One quasi-randomized and nine randomized controlled studies were included, with a total of 436 participants. Eight studies analyzed oral supplementation with antioxidants and two inhaled supplements.One study (n = 46) of an oral combined supplement demonstrated a significant difference in forced expiratory volume at one second expressed as per cent predicted after two weeks in favour of the control group, mean difference -4.30 (95% confidence interval -5.64 to -2.96); however a further study (n = 41) of oral supplementation with glutathione showed a significant improvement in this outcome and in forced vital capacity after six months from the treatment start, mean difference 17.40 (95% confidence interval 13.69 to 21.11) and 14.80 (95% confidence interval 9.66 to 19.94) respectively. The combined supplement study also indicated a significant improvement in quality of life favouring control, mean difference -0.06 points on the quality of well-being scale (95% confidence interval -0.12 to -0.01). Based on one study (n = 41) of oral glutathione supplementation in children, the supplements had a positive effect on the nutritional status (body mass index %) of the patients, mean difference 17.20 (95% confidence interval 12.17 to 22.23). In two studies (n = 83) that supplemented vitamin E, there was an improvement after two months in the blood levels of vitamin E, mean difference 11.78 μM/L (95% confidence interval 10.14 to 13.42).Based on one of the two studies of inhaled glutathione supplementation, there was an improvement in the forced expiratory volume at one second expressed as per cent predicted after three and six months (n = 153), mean difference 2.57 (95% confidence interval 2.24 to 2.90) and 0.97 (95% confidence interval 0.65 to 1.29) respectively. Only one of the studies reported quality of life data that could be analysed, but data showed no significant differences between treatment and control.None of the 10 included studies was judged to be free of bias. There appears to be conflicting evidence regarding the clinical effectiveness of antioxidant supplementation in cystic fibrosis. Based on the available evidence, glutathione (administered either orally or by inhalation) appears to improve lung function in some cases and decrease oxidative stress; however, due to the very intensive antibiotic treatment and other treatments that cystic fibrosis patients receive, the beneficial effect of antioxidants is very difficult to assess in patients with chronic infection without a very large population sample and a long-term (at least six months) study period. Further studies, especially in very young patients, examining clinically relevant outcomes, dose levels, timing and the elucidation of clear biological pathways by which oxidative stress is involved in cystic fibrosis, are necessary before a firm conclusion regarding effects of antioxidants supplementation can be drawn.

Oxidized forms of dietary antioxidants: Friends or foes?

Many clinical trials in which individuals received one or more dietary antioxidants failed to demonstrate conclusive effects of antioxidant supplementation. Antioxidant supplements do not seem to protect sufficiently against oxidative stress, oxidative damage or to increase lifespan. Some recent studies implied that antioxidant therapy can even increase mortality. In this paper, the idea is presented that antioxidants in their oxidative forms may have more health-beneficial effects than their reduced forms. It seems that it is not the anti-oxidative potential of the antioxidants that has the major role in health-improvement, but rather their involvement in cell signaling processes, regulation of transcription factor activities and other determinants of gene expression. Although oxidized forms of dietary antioxidants may be toxic, their low concentrations might trigger an adaptive stress response (hormesis) and provoke an increased endogenous antioxidant protection and an activation of damage repair processes. Thus, if proved beneficial, the food supplements should contain also low to moderate concentration of specific antioxidants in their oxidized forms.