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Absence of Effects of L-Arginine and L-Citrulline on Inflammatory Biomarkers and Oxidative Stress in Response to Physical Exercise: A Systematic Review with Meta-Analysis.
Porto, AA, Gonzaga, LA, Benjamim, CJR, Valenti, VE
Nutrients. 2023;15(8)
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L-citrulline is a non-essential amino acid that acts as a precursor to L-arginine. L-arginine is a semi-essential amino acid used for nitric oxide production which is crucial for maintaining physiological function and immune regulation. Previous research has shown that L-citrulline and L-arginine supplementation may offer antioxidant and anti-inflammatory benefits in reducing exercise-related oxidative stress and inflammation. This systematic review and meta-analysis included seven randomised controlled trials to investigate the effect of L-citrulline and L-arginine on antioxidants, oxidative stress, and inflammatory and anti-inflammatory markers. This systematic review and meta-analysis showed no significant improvements in oxidative stress and inflammation followed by the supplementation of L-citrulline and L-arginine before exercise. However, further robust studies that include different dosages and exercise intensities are required to assess the beneficial effects of L-citrulline and L-arginine supplements to support physical exercise-induced oxidative stress and inflammation due to the heterogeneity of the included studies. Healthcare professionals can use the results of this study to understand the potential benefits of L-citrulline and L-arginine supplementation in people prone to producing proinflammatory cytokines.
Abstract
The repercussions on oxidative and inflammatory stress markers under the effects of arginine and citrulline in response to exercise are not fully reached. We completed a systematic review to investigate the effects of L-Citrulline or L-Arginine on oxidative stress and inflammatory biomarkers following exercise. EMBASE, MEDLINE (PubMed), Cochrane Library, CINAHL, LILACS, and Web of Science databases were used to record the trials. This study includes randomized controlled trials (RCTs) and non-RCTs with subjects over 18 years old. Those under the intervention protocol consumed L-Citrulline or L-Arginine, and the controls ingested placebo. We recognized 1080 studies, but only 7 were included (7 studies in meta-analysis). We observed no difference between pre- vs. post-exercise for oxidative stress (subtotal = -0.21 [CI: -0.56, 0.14], p = 0.24, and heterogeneity = 0%. In the sub-group "L-Arginine" we found a subtotal = -0.29 [-0.71, 0.12], p = 0.16, and heterogeneity = 0%. For the "L-Citrulline" subgroup we observed a subtotal = 0.00 [-0.67, 0.67], p = 1.00, and heterogeneity was not applicable. No differences were observed between groups (p = 0.47), and I² = 0%) or in antioxidant activity (subtotal = -0.28 [-1.65, 1.08], p = 0.68, and heterogeneity = 0%). In the "L-Arginine" sub-group, we found a subtotal = -3.90 [-14.18, 6.38], p = 0.46, and heterogeneity was not applicable. For the "L-Citrulline" subgroup, we reported a subtotal = -0.22 [-1.60, 1.16], p = 0.75, and heterogeneity was not applicable. No differences were observed between groups (p = 0.49), and I² = 0%), inflammatory markers (subtotal = 8.38 [-0.02, 16.78], p = 0.05, and heterogeneity = 93%. Tests for subgroup differences were not applicable, and anti-inflammatory markers (subtotal = -0.38 [-1.15, 0.39], p = 0.34 and heterogeneity = 15%; testing for subgroup differences was not applicable). In conclusion, our systematic review and meta-analysis found that L-Citrulline and L-Arginine did not influence inflammatory biomarkers and oxidative stress after exercise.
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Comparison of L-Carnitine vs. Coq10 and Vitamin E for idiopathic male infertility: a randomized controlled trial.
Ma, L, Sun, Y
European review for medical and pharmacological sciences. 2022;26(13):4698-4704
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The World Health Organization (WHO) defines infertility as the inability to conceive after more than one year of regular unprotected intercourse. Male infertility has several different causes, ranging from genetic alterations to lifestyle choices to general medical diseases, medications, or even drugs. The aim of this study was to compare the efficacy of L-carnitine versus co-enzyme Q10 (CoQ10) and Vitamin E in improving outcomes in patients with idiopathic male infertility (asthenozoospermia [reduced sperm motility] or teratozoospermia [abnormal sperm morphology]). This study is based on the results of a randomised controlled trial which enrolled 143 patients with male infertility. Participants were randomly assigned to one of the two groups: intervention group (administered L-carnitine complex nutrient treatment) or the control group (administered CoQ10). Results show that: - after 3 months of treatment, sperm parameters improved with both L-carnitine and CoQ10 and vitamin E, except for sperm concentration with the latter. - comparing the two treatment modalities, the improvement was significantly better with L-carnitine as compared to CoQ10 and vitamin E for all three sperm parameters (concentration, progressive motility, and normal morphology). - a significant increase in the levels of testosterone and luteinizing hormone levels in patients on L-carnitine therapy, but only testosterone levels increased with CoQ10 and vitamin E. Authors conclude that future studies should examine clinical pregnancy rates in order to strengthen and warrant their findings.
Abstract
OBJECTIVE This study aimed at comparing sperm parameters and hormonal levels with L-carnitine vs. CoQ10 and Vitamin E therapy for patients with asthenozoospermia and teratozoospermia. PATIENTS AND METHODS A single-blind randomized controlled trial (RCT) was designed wherein patients were randomly allocated to receive L-carnitine complex nutrient treatment (study group - 15 g/bag, orally one bag at a time, twice a day) or CoQ10 (control group - 10 mg tablet orally, thrice daily) with Vitamin E (100 mg tablet orally, thrice daily) for three months. Outcome variables were sperm concentration, progressive sperm motility, normal sperm morphology, testosterone, follicle-stimulating hormone, luteinizing hormone (LH), and prolactin levels. RESULTS 143 patients were analyzed (73 in study and 70 in control group). Compared to baseline, sperm count, progressive sperm motility, and morphology improved significantly in the study group, but only progressive sperm motility and morphology improved in the control group. Serum testosterone levels significantly increased both in the study and control groups, while LH increased only in the study but not in the control group. All sperm parameters showed significantly better improvement in the study group, compared to the control group. Testosterone and LH levels were also higher in the study group compared to the control group. CONCLUSIONS L-carnitine significantly improves sperm motility, morphology, and concentration, while also improving testosterone and LH levels. Use of CoQ10 and Vitamin E resulted in improvement of only sperm motility, morphology, and testosterone levels. L-carnitine was found to be superior to the combination of CoQ10 and Vitamin E in improving sperm parameters. Further studies examining clinical pregnancy rates are needed to strengthen the evidence.
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Effect of vitamin E on Semen Quality Parameters: A Meta-Analysis of a Randomized Controlled Trial.
Wang, R, Wang, S, Song, Y, Zhou, H, Pan, Y, Liu, L, Niu, S, Liu, X
Urology journal. 2022;19(5):343-351
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The incidence of male infertility is increasing year by year. The mechanism of male infertility is complex. One of the important causes of male infertility is the decline in semen quality. The aim of this study was to evaluate the effectiveness of oral vitamin E in improving semen quality. This study is a meta-analysis of eight articles with a total of 459 patients, including 238 cases in the experimental group and 221 cases in the control group. Results show that oral vitamin E treatment could significantly increase the total sperm count and reduce the volume of semen. It was further found that oral vitamin E treatment for up to 6 months could improve the forward motility of sperm but not for 3 months. Authors conclude that vitamin E could increase the total sperm count and reduce the volume of semen in male infertility patients.
Abstract
PURPOSE To explore the effectiveness of vitamin E in male infertility, a systematic review and meta-analysis was conducted. MATERIALS AND METHODS The retrieval time was from January 1947 to May 2021, without language restriction. Stata 12.0 was used for the meta-analysis. RESULTS A total of 8 randomized controlled trials involving 459 patients were included. The results showed that after vitamin E treatment, semen volume was reduced (95% CI: - 0.55 to - 0.06, SMD = - 0.30, p = 0.015), total sperm count was increased (95% CI: 0.02-0.45, SMD = 0.23, p = 0.035), and the differences were statistically significant. There were no statistically significant differences in increasing sperm concentration (95% CI: -0.21-0.29, SMD = 0.04, p = 0.769), total sperm motility (95% CI: -0.01-0.42, SMD = 0.20, p = 0.061) or sperm forward motility rate (95% CI: -0.06-0.65, SMD = 0.29, p = 0.106). Subgroup analysis showed that vitamin E treatment for six months could improve sperm forward motility (95% CI: 0.46-1.14, SMD = 0.80, p <0.001). CONCLUSION Vitamin E could increase the total sperm count and reduce the volume of semen in male infertility patients, and long-term treatment could improve the forward motility rate of sperm. The decrease of semen volume may be the result of different abstinence time before and after the test.
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Efficacy and Safety of Q10 Ubiquinol With Vitamins B and E in Neurodevelopmental Disorders: A Retrospective Chart Review.
Cucinotta, F, Ricciardello, A, Turriziani, L, Mancini, A, Keller, R, Sacco, R, Persico, AM
Frontiers in psychiatry. 2022;13:829516
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The literature shows that oxidative stress represents a shared feature present in many brain disorders and more specifically in neurodevelopmental disorders (NDDs) including autism spectrum disorder, attention-deficit/hyperactivity disorder, and intellectual disability. The aim of this study was to verify retrospectively the clinical efficacy and safety of a metabolic support therapy (MST) with coenzyme Q10 (Q10 ubiquinol), vitamin E and complex-B vitamins in various neurodevelopmental disorders. This study is a retrospective chart review of 59 patients with NDDs. Results show that in terms of efficacy, MST was associated with clinical improvement in 45/59 (76.27%) patients. Whereas in terms of safety, side effects were mild and always manageable. Thus, this study provides retrospective evidence of efficacy and tolerability for a MST encompassing Q10-ubiquinol, vitamin E and complex-B vitamins in patients with different neurodevelopmental disorders. Authors conclude that their findings encourage further investigations of MST efficacy in neurodevelopmental disorders in order to confirm the generalisability of the study’s observations, verifying both efficacy, safety, treatment response rates and therapeutic effect size, separately in each major neurodevelopmental disorder.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Oxidative stress and mitochondrial dysfunction are reported to play a role in brain and neurological disorders.
- This retrospective chart review suggests that metabolic support therapy with Q10 ubiquinol, vitamin E and complex-B vitamins is well tolerated and produces some improvement in most patients with neurodevelopmental disorders, especially in the presence of intellectual disability.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A retrospective chart review study was conducted on the clinical efficacy and safety of metabolic support therapy (MST) with Q10 ubiquinol, vitamin E and complex-B vitamins in various neurodevelopmental disorders.
59 patients (49 Children and 6 Adults) between the ages of 2.5–39 years old diagnosed with Autism Spectrum Disorder (n=17), Autism Spectrum Disorder with co-morbid Intellectual Disability (n=19), Intellectual Disability or Global Developmental Delay (n=15), Attention-Deficit/Hyperactivity Disorder (n=3), and Intellectual Disability in Phelan-McDermid syndrome due to chr. 22q13.33 deletions (n=5) were included in the study.
Methods
Participants received 50-100mg Q10 ubiquinol, 30-60mg of vitamin E, 5.5mg-11mg of nicotinamide, 3mg-6mg of dexpanthenol, 0.45mg-0.09mg of riboflavin-5’-sodium phosphate, 5mg-10mg of inositol, pyridoxine hydrochloride, and 0.07mcg -1.40mcg of cyanocobalamin for three months. Different dosage levels were administered based on the participant’s body weight and the maximum daily allowance stated by Italy’s Ministry of Health. Patients remained on their prescribed antipsychotic medications during the study.
The Clinical Global Impression of Severity (CGI-S) scale, as well as the Clinical Global Impression of Improvement (CGI-I) scale was assessed by experienced Child and Adolescent or Adult Psychiatrists.
The clinical diagnosis was further confirmed using the Autism Diagnostic Observation Schedule – 2nd ed (ADOS-2) and the Autism Diagnostic Interview-Revised (ADIR) for ASD, the Griffiths Mental Development Scale (GMDS) for GDD, a cognitive test (Leiter-R,WPPSI-III,WISC-IV,WAISIV) for ID, the Conners Parent Rating Scale (CPRS) also in Teacher version (TRF) and the Batteria Italiana per l’ADHD (BIA) for ADHD.
At the endpoint, 45/59 (76.2%) of the subjects completed the study. No reasons were given for dropouts.
Results
Primary clinical outcomes were:
- Most widespread improvements were recorded in cognition (n=26 44,1%), adaptive functioning (n=26 44,1%) and social motivation (n=19 32.2%).
- Based on clinical chart reviews 45/59 (76.27%) patients responded to MST according to Clinical Global Impression of Severity scores.
- One 13-year-old boy with an intellectual disability, gained over 20 IQ points after consuming metabolic support therapy for 6 months.
- Mild side effects of hyperactivity and insomnia were reported in 18/59 (30%) of patients.
Clinical practice applications:
- Pharmacological treatments are prescribed to correct comorbid symptoms like sleep disorders, aggressiveness, and irritability in neurodevelopmental disorders like ASD. The efficacy of these treatments displays great interindividual variability depending not only on the treatment approach, therapist experience, and therapeutic setting but also on the genetic background of the patient.
- Oxidative stress and mitochondrial dysfunction have been described in many different brain and neurological disorders.
- Minimising the mitochondrial dysfunction produced by oxidative stress damage in brain disorders, while not directly correcting the primary mechanism responsible for the pathology, may nonetheless help to improve the clinical condition, acting as an indirect therapy.
- This study provides preliminary evidence of the efficacy and tolerability of a ‘metabolic support therapy’ encompassing Q10- ubiquinol, Vitamin E and complex-B vitamins in patients with different neurological disorders.
Considerations for future research:
- This study was based on a retrospective design using a small sample size.
- Randomised controlled trials for each single neurodevelopmental disorder are needed to conclusively demonstrate the efficacy of these mitochondrial bioenergetic and antioxidant agents and to estimate their therapeutic effect size.
Abstract
Increased oxidative stress and defective mitochondrial functioning are shared features among many brain disorders. The aim of this study was to verify retrospectively the clinical efficacy and safety of a metabolic support therapy with Q10 ubiquinol, vitamin E and complex-B vitamins in various neurodevelopmental disorders. This retrospective chart review study included 59 patients (mean age 10.1 ± 1.2 y.o., range 2.5-39 years; M:F = 2.47:1), diagnosed with Autism Spectrum Disorder (n = 17), Autism Spectrum Disorder with co-morbid Intellectual Disability (n = 19), Intellectual Disability or Global Developmental Delay (n = 15), Attention-Deficit/Hyperactivity Disorder (n = 3) and Intellectual Disability in Phelan-McDermid syndrome due to chr. 22q13.33 deletion (n = 5). After a minimum of 3 months of therapy, a positive outcome was recorded in 45/59 (76.27%) patients, with Clinical Global Impression-Improvement scores ranging between 1 ("very much improved") and 3 ("minimally improved"). The most widespread improvements were recorded in cognition (n = 26, 44.1%), adaptative functioning (n = 26, 44.1%) and social motivation (n = 19, 32.2%). Improvement rates differed by diagnosis, being observed most consistently in Phelan-McDermid Syndrome (5/5, 100%), followed by Intellectual Disability/Global Developmental Delay (13/15, 86.7%), Autism Spectrum Disorder with co-morbid Intellectual Disability (15/19, 78.9%), Autism Spectrum Disorder (11/17, 64.7%) and ADHD (1/3, 33.3%). No significant adverse event or side effect leading to treatment discontinuation were recorded. Mild side effects were reported in 18 (30.5%) patients, with the most frequent being increased hyperactivity (9/59, 15.3%). This retrospective chart review suggests that metabolic support therapy with Q10 ubiquinol, vitamin E and complex-B vitamins is well tolerated and produces some improvement in the majority of patients with neurodevelopmental disorders, especially in the presence of intellectual disability. Randomized controlled trials for each single neurodevelopmental disorder are now warranted to conclusively demonstrate the efficacy of these mitochondrial bioenergetic and antioxidant agents and to estimate their therapeutic effect size.
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Effect of mitochondrial-targeted antioxidants on glycaemic control, cardiovascular health, and oxidative stress in humans: A systematic review and meta-analysis of randomized controlled trials.
Mason, SA, Wadley, GD, Keske, MA, Parker, L
Diabetes, obesity & metabolism. 2022;24(6):1047-1060
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Reactive oxygen species (ROS) are free radical oxygen molecules produced by mitochondria, which cause molecular damage known as oxidative stress. Chronic diseases such as diabetes, heart disease, cancer, and Parkinson's disease are more likely to develop when ROS levels are elevated. Mitochondrial‐targeted antioxidants (mitoAOX) may be effective in treating chronic diseases by targeting mitochondrial ROS. In this systematic review and meta-analysis, 19 randomised controlled trials were included to evaluate the effects of mitoAOXs on glycaemic control, cardiovascular health, and oxidative stress in humans. The evidence is limited, but there were improvements in endothelial function, blood pressure, oxidative stress, and functional capacity. The mitoAOX agents, dosage, and participant characteristics varied between the studies, making it difficult to draw conclusions. Due to the heterogeneity of studies included in this study, there is a need for larger, longer-term robust studies to investigate mitoAOXs' effects on mitochondrial ROS and markers of oxidative stress in different clinical populations. As a result of this study, healthcare professionals can gain a better understanding of mitoAOX's potential in tackling oxidative stress. However, caution must be exercised before implementing it as a therapeutic strategy due to concerns over possible adverse effects and a low evidence certainty.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Mitochondria are a major producer of reactive oxygen species (ROS) in cells. Excess mitochondrial ROS has been implicated in the pathophysiology of various chronic diseases including Parkinson’s disease, cardiovascular disease (CVD), Type 2 diabetes and cancer.
- This review reported that there is limited evidence to support the use of mitoAOXs in the management of glycaemic control and cardiovascular health. However, there are promising findings on the effect of mitoAOXs on endothelial function that warrant consideration and further investigation in target clinical population groups.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Background
A systematic review and meta-analysis was conducted to evaluate the current evidence from randomised control trials (RCTs) in humans on the effects of mitochondrial-targeted antioxidant (mitoAOXs) on glycaemic control, cardiovascular health, and oxidative stress.
Methodology
19 Randomised control trials (n= 884 participants) using mitoAOXs (including Elamipretide, MitoQ and MitoTEMPO) were included from MEDLINE-PubMed, Scopus, EMBASE and Cochrane Library databases. A Cochrane Collaboration’s tool was used to assess risk bias and to grade the quality of the trials and their certainty of the evidence.
Results
Primary clinical outcomes were:
- A quantitative analysis on glycaemic control found no significant effect for fasting glucose in response to MitoQ supplementation.
- A quantitative analysis on cardiovascular health related outcomes found a significant lowering effect of mitoAOXs brachial flow-mediated dilation (FMD) (standardized mean difference: 1.19, 95% CI: 0.28, 2.16; I2: 67%) and an improved blood pressure (standardized mean difference: -0.32, 95% CI:-0.95, 0.30; I2: 0%) in patients with atherosclerosis-related impairment of renal blood flow.
- A quantitative analysis on oxidative stress-related outcomes found no significant effect of mitoAOX on malondialdehyde or F2-Isoprostanes.
Clinical practice applications:
- The findings from this review suggest limited evidence to support the use of mitoAOX in the management of glycaemic control or cardiovascular health.
- However, there are some potential promising findings which included improved endothelial function (particularly brachial FMD) and improved blood pressure in patients with atherosclerosis-related impairment of renal blood flow.
- Based on this review, practitioners may consider recommending the use of mitoAOXs only in quite specific circumstances, namely to improve endothelial function in patients with a risk of brachial FMD or high blood pressure associated with atherosclerosis-related impairment of renal blood flow.
Considerations for future research:
- The studies included in this review were mostly one to three months in duration therefore, there is a need for long-term, follow-up studies to be conducted to better investigate these outcomes.
- Given the pathogenic factors of elevated mitochondrial ROS and oxidative stress in chronic diseases such as CVD and Type2 diabetes, further investigation is needed into the effects of mitoAOXs on mitochondrial ROS and oxidative stress markers in target clinical population groups.
- It appears that mitoAOXs may improve endothelial function, therefore further research is needed to focus on the effect of mitoAOXs on endothelial function in target clinical populations.
- Additionally, further reviews are required to provide a more comprehensive review of the safety and adverse effects of mitoAOXs.
- Furthermore, only antioxidants specific to microconidia were included in this review. It is possible that other more general acting antioxidants may have redox-related effects in mitochondria. Therefore, a more comprehensive review is needed to include all possible antioxidant compounds that have mitochondrial effect.
Abstract
AIM: To investigate the effects of mitochondrial-targeted antioxidants (mitoAOXs) on glycaemic control, cardiovascular health, and oxidative stress outcomes in humans. MATERIALS AND METHODS Randomized controlled trials investigating mitoAOX interventions in humans were searched for in databases (MEDLINE-PubMed, Scopus, EMBASE and Cochrane Library) and clinical trial registries up to 10 June 2021. The Cochrane Collaboration's tool for assessing risk of bias and Grading of Recommendations, Assessment, Development and Evaluations were used to assess trial quality and evidence certainty, respectively. RESULTS Nineteen studies (n = 884 participants) using mitoAOXs (including Elamipretide, MitoQ and MitoTEMPO) were included in the systematic review. There were limited studies investigating the effects of mitoAOXs on glycaemic control; and outcomes and population groups in studies focusing on cardiovascular health were diverse. MitoAOXs significantly improved brachial flow-mediated dilation (n = 3 trials; standardized mean difference: 1.19, 95% CI: 0.28, 2.16; I2 : 67%) with very low evidence certainty. No significant effects were found for any other glycaemic, cardiovascular or oxidative stress-related outcomes with mitoAOXs in quantitative analyses, with evidence certainty rated mostly as low. There was a lack of serious treatment-emergent adverse events with mitoAOXs, although subcutaneous injection of Elamipretide increased mild-moderate injection site-related events. CONCLUSION While short-term studies indicate that mitoAOXs are generally well tolerated, there is currently limited evidence to support the use of mitoAOXs in the management of glycaemic control and cardiovascular health. Review findings suggest that future research should focus on the effects of mitoAOXs on glycaemic control and endothelial function in target clinical population groups.
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Selenium, antioxidants, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials.
Jenkins, DJA, Kitts, D, Giovannucci, EL, Sahye-Pudaruth, S, Paquette, M, Blanco Mejia, S, Patel, D, Kavanagh, M, Tsirakis, T, Kendall, CWC, et al
The American journal of clinical nutrition. 2020;112(6):1642-1652
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Oxidative damage is a shared characteristic in chronic diseases such as cardiovascular disease (CVD), diabetes, cancer and ageing. Antioxidants mitigate the impact of oxidants and have been widely investigated in ageing and disease. However, the evidence for supplementary antioxidants has been mixed and some authorities have advised against the use of certain single nutrients for the prevention of CVD or cancer. This systematic review and meta-analysis focused on selenium due to its vital role in the antioxidant system and associations of low selenium blood levels with increased risk of CVD, cancers and death. The study included 43 randomised controlled trials (RCTs) evaluating the effect of supplemental selenium and antioxidants with or without selenium and their impact on CVD risk, cancer and all-cause mortality. Overall supplemental selenium or antioxidants alone did not seem to be associated with CVD outcomes, cancer, CVD and cancer mortality, or all-cause mortality. On close examination, a decreased risk was seen for CVD mortality when antioxidants were combined with selenium, whilst antioxidant mixtures without selenium demonstrated an increased risk in all-cause mortality. The findings did not seem to be influenced by dietary selenium intake. The authors suggested that inclusion of selenium as part of an antioxidant mix could be key for an antioxidant associated risk reduction. However, in the absence of further long term studies, a balanced antioxidant-rich diet was advocated as the safest approach. In clinical practice, where antioxidant support beyond diet is warranted, supplemental antioxidant use should be concurrent with adequate selenium supplementation, with dose benefits of 50-200mcg observed.
Abstract
BACKGROUND Antioxidants have been promoted for cardiovascular disease (CVD) risk reduction and for the prevention of cancer. Our preliminary analysis suggested that only when selenium was present were antioxidant mixtures associated with reduced all-cause mortality. OBJECTIVE We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the effect of selenium supplementation alone and of antioxidant mixtures with or without selenium on the risk of CVD, cancer, and mortality. METHODS We identified studies using the Cochrane Library, Medline, and Embase for potential CVD outcomes, cancer, and all-cause mortality following selenium supplementation alone or after antioxidant supplement mixtures with and without selenium up to June 5, 2020. RCTs of ≥24 wk were included and data were analyzed using random-effects models and classified by the Grading of Recommendations, Assessment, Development, and Evaluation approach. RESULTS The meta-analysis identified 9423 studies, of which 43 were used in the final analysis. Overall, no association of selenium alone or antioxidants was seen with CVD and all-cause mortality. However, a decreased risk with antioxidant mixtures was seen for CVD mortality when selenium was part of the mix (RR: 0.77; 95% CI: 0.62, 0.97; P = 0.02), with no association when selenium was absent. Similarly, when selenium was part of the antioxidant mixture, a decreased risk was seen for all-cause mortality (RR: 0.90; 95% CI: 0.82, 0.98; P = 0.02) as opposed to an increased risk when selenium was absent (RR: 1.09; 95% CI: 1.04, 1.13; P = 0.0002). CONCLUSION The addition of selenium should be considered for supplements containing antioxidant mixtures if they are to be associated with CVD and all-cause mortality risk reduction. This trial was registered at https://www.crd.york.ac.uk/PROSPERO/ as CRD42019138268.
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Inflammaging and Oxidative Stress in Human Diseases: From Molecular Mechanisms to Novel Treatments.
Zuo, L, Prather, ER, Stetskiv, M, Garrison, DE, Meade, JR, Peace, TI, Zhou, T
International journal of molecular sciences. 2019;20(18)
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Reactive oxygen species (ROS) are produced during normal metabolic processes or can be induced by environmental factors. High levels of ROS in the cell can lead to oxidation causing cellular damage and a subsequent increase in inflammation, which is a significant contributor to disease. Age-associated increases in such chronic, low-grade inflammation is also referred to as inflammaging. This review summarizes how inflammaging plays a role in various age-related health conditions. Described are the mechanisms of how ROS and the age-related decline in cellular turn-over and immune activation contribute to the pathology of cardiovascular disease, cancer, neurodegeneration concerning Alzheimer’s and Parkinson’s disease, diabetes and rheumatoid arthritis. Furthermore, the authors discuss potential treatments that could assist in the management of such inflammaging-related diseases. These include vaccines to stimulate immune activity, stem cell intervention, drugs like metformin, nutritional and nutraceutical supplements like zinc, vitamin E, vitamins C, D, carotenoids, polyphenols and flavonoids like resveratrol, red algae extract and melatonin. Addressed are also general dietary concepts like calorie restriction, the benefits of the Mediterranean diet or a whole foods diet, and the potential of specific plant derived compounds like baicalin and sulforaphanes. The authors also briefly highlight the importance of the gut microbiome, as a poor gut microbiota has been associated with unfavourable age-related immune alterations and overall inflammaging. This review provides a comprehensive resource, detailing the effects and mechanisms of oxidative damage and its contribution to age-related diseases, including a list of interventions to consider when navigating the impact and risks associated with inflammaging.
Abstract
It has been proposed that a chronic state of inflammation correlated with aging known as inflammaging, is implicated in multiple disease states commonly observed in the elderly population. Inflammaging is associated with over-abundance of reactive oxygen species in the cell, which can lead to oxidation and damage of cellular components, increased inflammation, and activation of cell death pathways. This review focuses on inflammaging and its contribution to various age-related diseases such as cardiovascular disease, cancer, neurodegenerative diseases, chronic obstructive pulmonary disease, diabetes, and rheumatoid arthritis. Recently published mechanistic details of the roles of reactive oxygen species in inflammaging and various diseases will also be discussed. Advancements in potential treatments to ameliorate inflammaging, oxidative stress, and consequently, reduce the morbidity of multiple disease states will be explored.
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Association of l-Arginine Supplementation with Markers of Endothelial Function in Patients with Cardiovascular or Metabolic Disorders: A Systematic Review and Meta-Analysis.
Rodrigues-Krause, J, Krause, M, Rocha, IMGD, Umpierre, D, Fayh, APT
Nutrients. 2018;11(1)
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L-arginine is an amino acid supplement that has shown potential for treating cardiovascular and metabolic diseases, however the current evidence has not produced clear results. The aim of this systematic review and meta-analysis was to verify the effects of L-arginine supplementation in individuals with cardiovascular disease, obesity or diabetes. Of the existing research, 13 studies were included for data extraction. The major outcome analysed was blood flow with a focus on specific biochemical markers that regulate vascular dilation. Based on the current literature, no difference was found between oral L-arginine supplementation and improvements in vascular function compared with placebo. The authors conclude this review may provide insight into potential mechanisms for improving endothelial function in individuals experiencing cardiovascular risk, but also note there were significant differences among the participants and intervention strategies in the studies reviewed.
Abstract
l-Arginine supplementation is a potential therapy for treating cardiovascular and metabolic diseases. However, the use of distinct l-arginine sources, intervened populations, and treatment regimens may have yielded confusion about their efficacy. This research constitutes a systematic review and meta-analysis summarizing the effects of l-arginine supplementation compared to placebo in individuals with cardiovascular disease (CVD), obesity, or diabetes. Eligibility criteria included randomized clinical trials and interventions based on oral supplementation of l-arginine with a minimum duration of three days; comparison groups consisted of individuals with the same disease condition receiving an oral placebo substance. The primary outcome was flow-mediated dilation, and secondary outcomes were nitrite/nitrate (NOx) rate and asymmetric dimethylarginine (ADMA). Statistical heterogeneity among studies included in the meta-analyses was assessed using the inconsistency index (I2). Fifty-four full-text articles from 3761 retrieved references were assessed for eligibility. After exclusions, 13 studies were included for data extraction. There was no difference in blood flow after post-ischemic hyperemia between the supplementation of l-arginine and placebo groups before and after the intervention period (standardized mean difference (SMD) = 0.30; 95% confidence intervals (CIs) = -0.85 to 1.46; I2 = 96%). Sensitivity analysis showed decreased heterogeneity when the studies that most favor arginine and placebo were removed, and positive results in favor of arginine supplementation were found (SMD = 0.59; 95% CIs = 0.10 to 1.08; I2 = 75%). No difference was found in meta-analytical estimates of NOx and ADMA responses between arginine or placebo treatments. Overall, the results indicated that oral l-arginine supplementation was not associated with improvements on selected variables in these patients (PROSPERO Registration: CRD42017077289).
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Effect of purple sweet potato leaf consumption on the modulation of the antioxidative status in basketball players during training.
Chang, WH, Chen, CM, Hu, SP, Kan, NW, Chiu, CC, Liu, JF
Asia Pacific journal of clinical nutrition. 2007;16(3):455-61
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Purple sweet potato leaves (PSPLs) have a high polyphenol content and have been shown to exhibit free-radical scavenging properties. During a training period athletes experience exercise-induced oxidative stress, and many studies have indicated that polyphenols can help prevent oxidative damage. Currently there is limited information on the physiologic and biochemical effects of dietary PSPLs in humans. The aim of this crossover study was to examine the effect of PSPLs on a variety of antioxidant status biomarkers in fifteen elite basketball players. Participants were enrolled for seven weeks and consumed a PSPL-rich diet and a control diet with a washout period in between. This study found that PSPL consumption for two weeks led to a significant increase in total plasma polyphenol concentration and vitamin E and C levels, and demonstrated a protective effect on lipid and DNA oxidation. The authors conclude that can a polyphenol-rich diet can modulate the anti-oxidative status of athletes during a training period.
Abstract
The aim of this study was to evaluate the effect of purple sweet potato leaves (PSPLs) consumption on antioxidative status and its modulation of that status in basketball players during training period. Fifteen elite basketball players were enrolled in this study. The seven-week study consisted of a run-in (week 1), PSPLs diet (daily consumption of 200 g PSPLs) (weeks 2, 3), washout (weeks 4, 5), and control diet (low polyphenol, with the amount of carotenoids adjusted to the same level as that of PSPLs) (weeks 6, 7). Blood and urine samples were taken for biochemical analysis. Compared with the control group, the results showed that PSPLs consumption led to a significant increase of plasma polyphenol concentration and vitamin E and C levels. Low density lipoprotein (LDL) lag time was significantly longer in the PSPLs group. A significant decrease of urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) was noted; however, there was no significant change in plasma glutathione (GSH), total antioxidant status (TAS) and malondialdehyde + 4-hydroxy-2(E)-nonenal level after consuming the PSPLs diet. In conclusion, consumption of PSPLs diet for 2 weeks may reduce lipid and DNA oxidation that can modulate the antioxidative status of basketball players during training period.