Influence of Oral Vitamin E Therapy on Micro-Inflammation and Cardiovascular Disease Markers in Chronic Hemodialysis Patients

Supplementation with antioxidant micronutrients in pregnant women with obesity: a randomized controlled trial

BACKGROUND/OBJECTIVE

Obesity increases maternal morbidity and adversely affects child health. Maternal inflammation may play a role in adverse outcomes. The objective of this study was to determine whether providing a higher dose of antioxidant micronutrients to pregnant women with obesity would raise concentrations of key antioxidant vitamins and impact inflammation and oxidative stress during pregnancy.

SUBJECTS/METHODS

This was a double-blind, randomized controlled trial. We recruited pregnant women with a body mass index (BMI) ≥ 30 kg/m2 at their initial prenatal visit ( < 13 weeks gestation) and collected blood and urine samples at baseline, 24-28 weeks, and 32-36 weeks to measure micronutrient concentrations (vitamin C, E, B6 and folate), markers of inflammation (C-reactive protein, interleukin-6, 8, and 1β) and oxidative stress (8-epi-PGF2α and malondialdehyde). We collected maternal and infant health data from enrollment to delivery as secondary outcomes. We enrolled 128 participants (64 in each arm), and 98 (49 in each arm) completed follow-up through delivery.

INTERVENTION

Both groups received a standard prenatal vitamin containing the recommended daily allowance of micronutrients in pregnancy. In addition, the intervention group received a supplement with 90 mg vitamin C, 30 αTU vitamin E, 18 mg vitamin B6, and 800 μg folic acid, and the control group received a placebo.

RESULTS

The intervention group had higher vit B6 (log transformed (ln), β 24-28 weeks: 0.76 nmol/L (95% CI: 0.40, 1.12); β 32-36 weeks: 0.52 nmol/L (95% CI: 0.17, 0.88)) than the control group. Vitamins C, E, erythrocyte RBC folate concentrations did not differ by randomization group. The intervention did not impact biomarkers of inflammation or oxidative stress. There were no differences in maternal or neonatal clinical outcomes by randomization group.

CONCLUSIONS

Higher concentrations of antioxidant vitamins during pregnancy increased specific micronutrients and did not impact maternal inflammation and oxidative stress, which may be related to dosing or type of supplementation provided.

CLINICAL TRIAL REGISTRATION

Clinical Trial Identification Number: NCT02802566; URL of the Registration Site: www.

CLINICALTRIALS

gov .

Antioxidants for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular disease (CVD) and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor. Antioxidant therapy decreases oxidative stress and may consequently reduce cardiovascular morbidity and death in people with CKD. This is an update of a Cochrane review first published in 2012.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on death and cardiovascular and kidney endpoints in adults with CKD stages 3 to 5, patients undergoing dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies until 15 November 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials investigating the use of antioxidants, compared with placebo, usual or standard care, no treatment, or other antioxidants, for adults with CKD on cardiovascular and kidney endpoints.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using random effects models and expressed as risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 95 studies (10,468 randomised patients) that evaluated antioxidant therapy in adults with non-dialysis-dependent CKD (31 studies, 5342 patients), dialysis-dependent CKD (41 studies, 3444 patients) and kidney transplant recipients (21 studies, 1529 patients). Two studies enrolled dialysis and non-dialysis patients (153 patients). Twenty-one studies assessed the effects of vitamin antioxidants, and 74 assessed the effects of non-vitamin antioxidants. Overall, the quality of included studies was moderate to low or very low due to unclear or high risk of bias for randomisation, allocation concealment, blinding, and loss to follow-up. Compared with placebo, usual care, or no treatment, antioxidant therapy may have little or no effect on cardiovascular death (8 studies, 3813 patients: RR 0.94, 95% CI 0.64 to 1.40; I² = 33%; low certainty of evidence) and probably has little to no effect on death (any cause) (45 studies, 7530 patients: RR 0.95, 95% CI 0.82 to 1.11; I² = 0%; moderate certainty of evidence), CVD (16 studies, 4768 patients: RR 0.79, 95% CI 0.63 to 0.99; I² = 23%; moderate certainty of evidence), or loss of kidney transplant (graft loss) (11 studies, 1053 patients: RR 0.88, 95% CI 0.67 to 1.17; I² = 0%; moderate certainty of evidence). Compared with placebo, usual care, or no treatment, antioxidants had little to no effect on the slope of urinary albumin/creatinine ratio (change in UACR) (7 studies, 1286 patients: MD -0.04 mg/mmol, 95% CI -0.55 to 0.47; I² = 37%; very low certainty of evidence) but the evidence is very uncertain. Antioxidants probably reduced the progression to kidney failure (10 studies, 3201 patients: RR 0.65, 95% CI 0.41 to 1.02; I² = 41%; moderate certainty of evidence), may improve the slope of estimated glomerular filtration rate (change in eGFR) (28 studies, 4128 patients: MD 3.65 mL/min/1.73 m², 95% CI 2.81 to 4.50; I² = 99%; low certainty of evidence), but had uncertain effects on the slope of serum creatinine (change in SCr) (16 studies, 3180 patients: MD -13.35 µmol/L, 95% CI -23.49 to -3.23; I² = 98%; very low certainty of evidence). Possible safety concerns are an observed increase in the risk of infection (14 studies, 3697 patients: RR 1.30, 95% CI 1.14 to 1.50; I² = 3%; moderate certainty of evidence) and heart failure (6 studies, 3733 patients: RR 1.40, 95% CI 1.11 to 1.75; I² = 0; moderate certainty of evidence) among antioxidant users. Results of studies with a low risk of bias or longer follow-ups generally were comparable to the main analyses.

AUTHORS' CONCLUSIONS

We found no evidence that antioxidants reduced death or improved kidney transplant outcomes or proteinuria in patients with CKD. Antioxidants likely reduce cardiovascular events and progression to kidney failure and may improve kidney function. Possible concerns are an increased risk of infections and heart failure among antioxidant users. However, most studies were of suboptimal quality and had limited follow-up, and few included people undergoing dialysis or kidney transplant recipients. Furthermore, the large heterogeneity in interventions hampers drawing conclusions on the efficacy and safety of individual agents.

Association between the composite dietary antioxidant index and chronic kidney disease: evidence from NHANES 2011-2018

Objectives: There is growing evidence that antioxidant-rich diets protect against chronic kidney disease (CKD). However, the relationship between the Composite Dietary Antioxidant Index (CDAI), an important measure of an antioxidant diet, and CKD has received little attention. Therefore, here we investigated the relationship between the CDAI and CKD through a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2011-2018 data. Methods: The CDAI was calculated based on the intake of six dietary antioxidants. A survey-based multivariate linear regression analysis was performed to analyze the independent relationship between the CDAI and CKD. Weighted multivariate regression and subgroup analyses were conducted to explore the relationship between the CDAI and CKD. Results: A total of 6874 NHANES participants represented 181.9 million non-institutionalized US residents (mean age, 46.43 ± 0.38 years; 49.87% female; 40.62% non-Hispanic white; 20.24% non-Hispanic black; and 13.94% Mexican American). The weighted linear regression model with full adjustment for confounding variables was -0.0155 (-0.0417, 0.0107) for Q2 (P for trend <0.0001), -0.0052 (-0.0346, 0.0242) for Q3 (P for trend <0.0001), and -0.0305 (-0.0491, -0.0120) for Q4 (P for trend = 0.0094) upon comparison with the lowest quartile of the CDAI. None of the interactions in any subgroup analysis were statistically significant except for individuals with a history of diabetes or the aged population (≥60 years) (P for interaction <0.05). Conclusions: The CDAI was positively associated with a lower prevalence of CKD in adults in the United States. Further large-scale prospective studies are required to analyze the role of the CDAI in CKD.

Beneficial Effects of Vitamin E Supplementation on Endothelial Dysfunction, Inflammation, and Oxidative Stress Biomarkers in Patients Receiving Hemodialysis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Inflammation and oxidative stress are closely related to cardiovascular complications and atherosclerosis, and have the potential to lead to an increase in death in patients receiving hemodialysis. Vitamin E has antioxidant and anti-inflammatory properties. We conducted a systematic review and meta-analysis to assess the effects of vitamin E supplementation on endothelial dysfunction, inflammation, and oxidative stress biomarkers in adult patients receiving hemodialysis. We searched the MEDLINE, EMBASE, Web of Science, and Cochrane Library databases and identified randomized controlled trials of adult patients receiving hemodialysis until 30 August 2021. A total of 11 trials with 491 randomized patients were included. The pooled data indicated that vitamin E supplementation significantly decreased intercellular adhesion molecule-1 [standardized mean difference (SMD): -1.35; 95% confidence interval (CI): -2.57, -0.13; p = 0.03, I2 = 89%], vascular cell adhesion molecule-1 (SMD: -1.08; 95% CI: -2.05, -0.11; p = 0.03, I2 = 81%), C-reactive protein (SMD: -0.41; 95% CI: -0.75, -0.07; p = 0.02, I2 = 64%), and malondialdehyde (SMD: -0.76; 95% CI: -1.26, -0.25; p = 0.003, I2 = 77%) levels, but not interleukin-6 levels compared to those in the control group. Our results suggest that vitamin E supplementation may help alleviate oxidative stress and both vascular and systemic inflammation in patients receiving hemodialysis.

Effects of pomegranate peel extract and vitamin E on the inflammatory status and endothelial function in hemodialysis patients: a randomized controlled clinical trial

Inflammation and endothelial dysfunction are major problems in hemodialysis (HD) patients. This study assessed the effects of an 8 week administration of pomegranate peel extract (PPE) and vitamin E (Vit E) alone or in combination on the biomarkers of inflammation, including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), and the biomarkers of endothelial function, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and P-selectin, in HD patients. In a randomized, double-blind, parallel, placebo-controlled trial, 100 HD patients were randomly divided into 4 equal groups: (a) PPE + Vit E, received 2 pomegranate tablets (each tablet contained 225 mg PPE, equal to 90 mg ellagic acid) + 1 Vit E soft gel (400 IU) daily, (b) PPE, received 2 pomegranate tablets + 1 Vit E placebo soft gel daily, (c) Vit E, received 1 Vit E soft gel + 2 pomegranate placebo tablets daily, and (d) placebo, received 2 pomegranate placebo tablets + 1 Vit E placebo soft gel daily. For group allocation, a stratified block randomization procedure based on sex, age, and HD duration was used. Each intervention product and its placebo had identical shape, color, size, and packaging. Consumption of PPE + Vit E significantly reduced the serum CRP level (mean change: -7.12 ± 4.59 mg l-1, P < 0.001) compared to other groups, while reduced levels of IL-6 (mean change: -2.19 ± 2.33 pg ml-1, P < 0.001), TNF-α (mean change: -2.41 ± 3.21 pg ml-1, P = 0.008), ICAM-1 (mean change: -64.2 ± 111.0 ng ml-1, P = 0.017), and VCAM-1 (mean change: -117.7 ± 177.1 ng ml-1, P = 0.002) were observed compared to the control. There was no significant difference in the P-selectin level among the groups. Consumption of PPE or Vit E alone significantly reduced the CRP level (mean change for PPE: -3.58 ± 5.41 mg l-1, P < 0.001; mean change for Vit E: -3.25 ± 8.29 mg l-1, P = 0.002) compared to the control. As a result, consumption of PPE in combination with Vit E enhanced the inflammatory status and endothelial function in HD patients.

The effect of vitamin E supplementation on selected inflammatory biomarkers in adults: a systematic review and meta-analysis of randomized clinical trials

The previous meta-analysis of clinical trials revealed a beneficial effect of vitamin E supplementation on serum C-reactive protein (CRP) concentrations; however, it is unknown whether this vitamin has the same influence on other inflammatory biomarkers. Also, several clinical trials have been published since the release of earlier meta-analysis. Therefore, we aimed to conduct a comprehensive meta-analysis to summarize current evidence on the effects of vitamin E supplementation on inflammatory biomarkers in adults. We searched the online databases using relevant keywords up to November 2019. Randomized clinical trials (RCTs) investigating the effect of vitamin E, compared with the placebo, on serum concentrations of inflammatory cytokines were included. Overall, we included 33 trials with a total sample size of 2102 individuals, aged from 20 to 70 years. Based on 36 effect sizes from 26 RCTs on serum concentrations of CRP, we found a significant reduction following supplementation with vitamin E (− 0.52, 95% CI − 0.80, − 0.23 mg/L, P < 0.001). Although the overall effect of vitamin E supplementation on serum concentrations of interleukin-6 (IL-6) was not significant, a significant reduction in this cytokine was seen in studies that used α-tocopherol and those trials that included patients with disorders related to insulin resistance. Moreover, we found a significant reducing effect of vitamin E supplementation on tumor necrosis factor-α (TNF-α) concentrations at high dosages of vitamin E; such that based on dose–response analysis, serum TNF-α concentrations were reduced significantly at the dosages of ≥ 700 mg/day vitamin E (P_{non-linearity} = 0.001). Considering different chemical forms of vitamin E, α-tocopherol, unlike other forms, had a reducing effect on serum levels of CRP and IL-6. In conclusion, our findings revealed a beneficial effect of vitamin E supplementation, particularly in the form of α-tocopherol, on subclinical inflammation in adults. Future high-quality RCTs should be conducted to translate this anti-inflammatory effect of vitamin E to the clinical setting.

KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for nutrition in kidney diseases since 1999. Since the publication of the first KDOQI nutrition guideline, there has been a great accumulation of new evidence regarding the management of nutritional aspects of kidney disease and sophistication in the guidelines process. The 2020 update to the KDOQI Clinical Practice Guideline for Nutrition in CKD was developed as a joint effort with the Academy of Nutrition and Dietetics (Academy). It provides comprehensive up-to-date information on the understanding and care of patients with chronic kidney disease (CKD), especially in terms of their metabolic and nutritional milieu for the practicing clinician and allied health care workers. The guideline was expanded to include not only patients with end-stage kidney disease or advanced CKD, but also patients with stages 1-5 CKD who are not receiving dialysis and patients with a functional kidney transplant. The updated guideline statements focus on 6 primary areas: nutritional assessment, medical nutrition therapy (MNT), dietary protein and energy intake, nutritional supplementation, micronutrients, and electrolytes. The guidelines primarily cover dietary management rather than all possible nutritional interventions. The evidence data and guideline statements were evaluated using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Efficacy of Nutritional Interventions on Inflammatory Markers in Haemodialysis Patients: A Systematic Review and Limited Meta-Analysis

Low-grade chronic inflammation is prevalent in patients undergoing haemodialysis (HD) treatment and is linked to the development of premature atherosclerosis and mortality. The non-pharmacological approach to treat inflammation in HD patients through nutritional intervention is well cited. We aimed to assess the efficacy of different nutritional interventions at improving inflammatory outcomes in HD patients, based on markers such as C-reactive protein (CRP), interleukin-6 (IL-6), and tumour necrosis factor-α (TNF-α). We searched PubMed, Cochrane Library, and Embase for randomized controlled trials (RCT) published before June 2017. Inclusion criteria included RCTs on adult patients on maintenance HD treatment with duration of nutritional interventions for a minimum 4 weeks. Risk of bias was assessed using the Jadad score. In total, 46 RCTs experimenting different nutritional interventions were included in the review and categorized into polyphenols rich foods, omega-3 fatty acids, antioxidants, vitamin D, fibres, and probiotics. Meta-analyses indicated significant reduction in CRP levels by omega-3 fatty acids (Random model effect: -0.667 mg/L, p < 0.001) and vitamin E (fixed model effect: -0.257 mg/L, p = 0.005). Evidence for other groups of nutritional interventions was inconclusive. In conclusion, our meta-analysis provided evidence that omega-3 fatty acids and vitamin E could improve inflammatory outcomes in HD patients.

Vitamin E tocotrienol supplementation improves lipid profiles in chronic hemodialysis patients

PURPOSE

Chronic hemodialysis patients experience accelerated atherosclerosis contributed to by dyslipidemia, inflammation, and an impaired antioxidant system. Vitamin E tocotrienols possess anti-inflammatory and antioxidant properties. However, the impact of dietary intervention with Vitamin E tocotrienols is unknown in this population.

PATIENTS AND METHODS

A randomized, double-blind, placebo-controlled, parallel trial was conducted in 81 patients undergoing chronic hemodialysis. Subjects were provided daily with capsules containing either vitamin E tocotrienol-rich fraction (TRF) (180 mg tocotrienols, 40 mg tocopherols) or placebo (0.48 mg tocotrienols, 0.88 mg tocopherols). Endpoints included measurements of inflammatory markers (C-reactive protein and interleukin 6), oxidative status (total antioxidant power and malondialdehyde), lipid profiles (plasma total cholesterol, triacylglycerols, and high-density lipoprotein cholesterol), as well as cholesteryl-ester transfer protein activity and apolipoprotein A1.

RESULTS

TRF supplementation did not impact any nutritional, inflammatory, or oxidative status biomarkers over time when compared with the baseline within the group (one-way repeated measures analysis of variance) or when compared with the placebo group at a particular time point (independent t-test). However, the TRF supplemented group showed improvement in lipid profiles after 12 and 16 weeks of intervention when compared with placebo at the respective time points. Normalized plasma triacylglycerols (cf baseline) in the TRF group were reduced by 33 mg/dL (P=0.032) and 36 mg/dL (P=0.072) after 12 and 16 weeks of intervention but no significant improvement was seen in the placebo group. Similarly, normalized plasma high-density lipoprotein cholesterol was higher (P<0.05) in the TRF group as compared with placebo at both week 12 and week 16. The changes in the TRF group at week 12 and week 16 were associated with higher plasma apolipoprotein A1 concentration (P<0.02) and lower cholesteryl-ester transfer protein activity (P<0.001).

CONCLUSION

TRF supplementation improved lipid profiles in this study of maintenance hemodialysis patients. A multi-centered trial is warranted to confirm these observations.

Role of alpha-lipoic acid in the management of anemia in patients with chronic renal failure undergoing hemodialysis

Introduction

Anemia associated with chronic kidney disease is a serious complication necessitating expenditure of huge medical efforts and resources. This study investigates the role of alpha-lipoic acid (ALA) in end stage renal disease patients undergoing hemodialysis. By the virtue of its antioxidative effects, ALA is expected to act as an erythropoietin (EPO) adjuvant, and also has extended beneficial effects on endothelial dysfunction.

Methods

Forty-four patients undergoing hemodialysis and receiving EPO were randomized into two groups: the first group received ALA 600 mg once daily for 3 months; while the other group represented the control group. Parameters measured at baseline and at end of study were hemoglobin, EPO doses, EPO resistance index (ERI), iron store indices, malondialdehyde, oxidized low-density lipoprotein (ox-LDL), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and asymmetric dimethylarginine (ADMA), as well as routine laboratory follow-up.

Results

EPO doses and ERI were significantly decreased in the treatment group, while they did not change in the control group. Hemoglobin, iron store indices, malondialdehyde, oxidized ox-LDL, IL-6, TNF-α, and ADMA were similar in both treatment and control groups at baseline, and did not change by the end of study period. Likewise, routine laboratory measures were not affected by the treatment.

Conclusion

ALA could be used in hemodialysis patients to reduce requirements for EPO. However, larger and longer term studies are required to clarify the exact role of ALA in hemodialysis as well as in pre-hemodialysis patients.

Cu/Zn ratios are associated with nutritional status, oxidative stress, inflammation, and immune abnormalities in patients on peritoneal dialysis

OBJECTIVES

We evaluated the relationship of the plasma copper/zinc (Cu/Zn) ratio with nutritional status, inflammation, oxidative stress, and immune function in peritoneal dialysis patients.

DESIGN AND METHODS

Clinical and laboratory parameters were measured in patients (n=45) and age- and sex-matched healthy individuals (n=30).

RESULTS

There were significant negative correlations of the Cu/Zn ratio with nutrition-related parameters (body mass index [BMI], creatinine, hemoglobin, and albumin) and antioxidant (vitamin C and E) levels and positive correlations of the Cu/Zn ratio with the levels of high sensitivity C-reactive protein (hs-CRP) and oxidation products (malondialdehyde [MDA] and protein carbonyl). The Cu/Zn ratio was negatively correlated with the percentages of B- and T-lymphocyte subsets and the ratio of CD4/CD8 antigens.

CONCLUSIONS

In peritoneal dialysis patients, elevated Cu/Zn ratios are associated with malnutrition, increased oxidative stress, inflammation, and disrupted immune status.

Circulating plasma antioxidants, inflammatory markers and asymptomatic carotid atherosclerosis in end-stage renal disease patients: a case control study

Few studies have been conducted on the relationship between antioxidant plasma vitamin concentrations, inflammatory markers and carotid atherosclerosis with inconclusive results in endstage renal disease (ESRD) patients. A case-control study was performed to investigate the relationship between plasma antioxidant concentrations, inflammatory markers, and carotid intima-media thickness (CIMT) in healthy subjects and in patients undergoing hemodialysis (HD). We enrolled 40 subjects (20 healthy, 20 with ESRD) asymptomatic for carotid atherosclerosis. After carotid ultrasound investigation (CUI), medical history data, physical examination, venous blood samples were collected. These were analyzed for concentrations of antioxidant vitamins (A, E), carotenoids (lycopene, beta-carotene), inflammatory markers (C-reactive protein, fibrinogen), and lipid profile. Low concentrations of vitamin A, vitamin E, lycopene, and beta-carotene were significantly associated with carotid atherosclerosis in patients with ESRD (p less than 0.001). In addition, high concentration of low density lipoprotein cholesterol and total cholesterol (p less than 0.01), C-reactive protein and fibrinogen (p less than 0.001) were also associated with carotid atherosclerosis, while other laboratory parameters considered (high density lipoprotein cholesterol and triglycerides) were not significantly associated with carotid atherosclerosis. A regular intake of foods rich in antioxidant vitamins with low fat concentrations may slow the progression of atherosclerotic process in this group of patients.

Antioxidant therapy does not ameliorate oxidative stress and inflammation in patients with end-stage renal disease

Oxidative stress and inflammation are common manifestations and major mediators of cardiovascular and many other complications of end-stage renal disease (ESRD). Oxidative stress and inflammation are intimately interrelated as each can cause the other. The present study tested the hypothesis that antioxidant therapy may alleviate oxidative stress and improve inflammation in ESRD patients. We studied 37 hemodialysis patients, of whom 20 were treated daily with a combination of vitamin E, 800 lU; vitamin C, 250 mg; vitamin B6, 100 mg; vitamin B12, 250 microg; and folic acid, 10 mg; whereas 17 patients were given placebo for 8 weeks. Predialysis levels of f-2 isoprostane and protein carbonyl (markers of oxidative stress), C-reactive protein (CRP) and IL6 (markers/ mediators of inflammation) were measured prior to and at 4 and 8 weeks after the onset of therapy. Kt/V, predialysis and postdialysis blood pressure, blood hemoglobin, erythropoietin requirement, plasma ferritin and transferrin saturation, and nutritional indexes were similar among the 2 groups at baseline and remained virtually unchanged throughout the study period. Likewise, plasma f-2 isoprostane, protein carbonyl, CRP, and IL-6 levels remained unchanged and were unaffected by antioxidant administration. In conclusion, the addition of a potent antioxidant cocktail to conventional vitamin supplements had no effect on severity of ESRD-induced oxidative stress, inflammation, hypertension, anemia, or nutritional disorders in hemodialysis patients. Thus, high doses of vitamins beyond the routinely prescribed vitamin supplements do not appear to be indicated in this population.

Effect of one-year oral alpha-tocopherol administration on the antioxidant defense system in hemodialysis patients

Oxidative stress is increased in hemodialysis (HD) patients and contributes to the increased morbidity and mortality in this population. Vitamin E is an antioxidant agent. In the present study the effect of prolonged oral alpha-tocopherol administration on the antioxidant defense system was evaluated. The antioxidant factors plasma total antioxidant status (TAS), red blood cell superoxide dismutase (SOD) activity and glutathione peroxidase (GPX) activity were evaluated with spectrometry in 27 HD patients. Measurements were performed before and after oral administration of alpha-tocopherol at a dose of 500 mg/d for a one-year period. Twenty HD patients received a placebo and 22 healthy volunteers served as controls. TAS was increased in HD patients. No difference was detected in SOD and GPX activity between HD patients and healthy volunteers. Tocopherol administration induced a significant decrease in TAS and SOD activity. Levels of GPX activity remained unaffected. All the evaluated factors remained stable in the HD patients receiving a placebo. Prolonged oral alpha-tocopherol administration in HD patients induces a decrease in some components of the antioxidant defense system, raising the possibility for a pro-oxidative role of vitamin E. Vitamin E is an antioxidant agent, but it is also known to have pro-oxidant action under special conditions that can be encountered in HD patients.

Cardiovascular disease in dialysis patients: do some antihypertensive drugs have specific antioxidant effects or is it just blood pressure reduction? Does antioxidant treatment reduce the risk for cardiovascular disease?

PURPOSE OF REVIEW

Patients with end-stage renal disease have an extremely high cardiovascular disease mortality. Oxidative stress is one of the 'nontraditional' risk factors for cardiovascular disease mortality in dialysis patients. This review discusses antioxidant activity of the commonly prescribed antihypertensive agents and the effects of antioxidant interventions on cardiovascular disease mortality in patients with end-stage renal disease.

RECENT FINDINGS

Several lines of evidence confirm antioxidant activity of the renin-angiotensin-aldosterone antagonists, some of the calcium channel blockers, carvedilol, and hydralazine. This appears to be independent of their antihypertensive activity. Clinical evidence of their superiority in improving cardiovascular disease endpoints in end-stage renal disease, however, is lacking. There are no randomized trials that have examined the effect of correcting oxidative stress on clinical endpoints. One randomized study in patients on hemodialysis reported a reduction in oxidative stress and the plasma methylarginines with valsartan and amlodipine but no clinical endpoints were examined.

SUMMARY

The effects of the antihypertensive agents with antioxidant activity on cardiovascular disease mortality in end-stage renal disease have not been examined in randomized clinical trials. These agents may offer specific clinical advantage in addition to lowering the blood pressure, but this remains to be proven. Two studies show a reduction in cardiovascular disease events with vitamin E and N-acetylcysteine in patients on hemodialysis without an effect on overall mortality.

Vitamin E does not modulate plasma lipid profile or C-reactive protein despite suppressing oxidative stress in orchiectomized rats

Vitamin E is known to improve antioxidant status and to prevent lipoprotein oxidation. However, the effect of vitamin E on other cardiovascular risk factors, including C-reactive protein (CRP) and lipid profile status, in orchiectomized rats is unknown. In the present study, 32 1-year-old male rats were randomized into two groups: a sham-control group (n = 8) and an orchiectomized group (n = 24). The orchiectomized group was divided into three groups of eight and assigned to one of the following treatments: orchiectomy (ORX), ORX + vitamin E mixture (65.6 mg/kg) diet, or ORX + vitamin E mixture (656 mg/kg) diet. For 120 days all four groups consumed a basal AIN-93M diet, while the vitamin E groups ate diets containing an additional vitamin E mixture. Four months after the study began, all the rats were killed, the blood was collected, and the plasma was assayed for antioxidant status, CRP, lipid profile, and indices of peroxidation. ORX decreased (P < .05) the plasma antioxidant status, superoxide dismutase (SOD) activity, and CRP level and increased (P < .05) the plasma malondialdeyde, nitrite, and lipid profile compared with that of the sham-control group. In contrast to the ORX group, supplementation with vitamin E mixture increased (P < .05) plasma antioxidant status and dose-dependently increased (P < .05) SOD activity, while the vitamin E decreased (P < .05) plasma malondialdeyde and nitrite. The vitamin E mixture had no effect on CRP or on lipid profiles when compared to the orchiectomized rats. In conclusion, vitamin E appears to reduce oxidative stress without modulating lipid profile or inflammatory response.