Effect of vitamins on the lipid profile of patients on regular hemodialysis

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.

Does Native Vitamin D Supplementation Have Pleiotropic Effects in Patients with End-Stage Kidney Disease? A Systematic Review of Randomized Trials

Vitamin D has been shown to have multiple pleiotropic effects beyond bone and mineral metabolism, with purported roles in cardiovascular disease, cancer, and host immunity. Vitamin D deficiency is common in patients with end-stage kidney disease (ESKD); however, current clinical practice has favored the use of the active hormone. Whether vitamin D deficiency should be corrected in patients with ESKD remains unclear, as few randomized trials have been conducted. In this systematic review, we summarize the current evidence examining whether vitamin D supplementation improves outcomes, beyond mineral metabolism, in patients with ESKD. Data from randomized controlled trials of adults with ESKD were obtained by searching Ovid MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and the Web of Science Core Collection from inception to February 2023. Twenty-three trials composed of 2489 participants were identified for inclusion. Data were synthesized by two independent reviewers and summarized in tables organized by outcome. Outcomes included measures of mortality, cardiovascular disease, inflammation, muscle strength/function, nutrition, patient well-being, and outcomes specific to ESKD including erythropoietin usage, pruritus, and dialysis access maturation. The Cochrane risk of Bias Tool (RoB 2, 2019) was used to assess study quality. Overall, our findings indicate a minimal and varied benefit of native vitamin D supplementation. From the largest studies included, we determine that vitamin D has no demonstrated effect on patient-reported measures of well-being or utilization of erythropoietin, nor does it change levels of the inflammation biomarker C-reactive protein. Included trials were heterogeneous with regards to outcomes, and the majority studied small participant populations with a relatively short follow-up. We conclude that vitamin D supplementation corrects vitamin D deficiency and is safe and well-tolerated in humans with ESKD. However, it is not clear from clinical trials conducted to date that a causal pathway exists between 25(OH)D and pleiotropic effects that is responsive to vitamin D treatment.

Association of vitamin D status with liver and kidney disease: A systematic review of clinical trials, and cross-sectional and cohort studies

Abstract. Background: Vitamin D deficiency (VDD) is a major public health problem. There are few comprehensive systematic reviews about the relationship between Vitamin D status and liver and renal disease in Iran.

Methods: We systemically searched the following databases: Web of Science; PubMed; Cochrane Library; Scopus; Science Direct; Google Scholar and two Iranian databases (Scientific Information Database (SID) and IranMedex) up until November 2017 to identify all randomized control trials (RCTs), case control, cross-sectional and cohort studies investigating the association between vitamin D and any form of liver or kidney disease.

Results: Vitamin D insufficiency, or deficiency (VDD), is highly prevalent in Iran, reports varying between 44.4% in Isfahan to 98% in Gorgan. There is also a high prevalence of VDD among patients with liver or kidney disease, and the administration of vitamin D supplements may have beneficial effects on lipid profile, blood glucose, liver function and fatty liver disease, and bone health. Low serum vitamin D levels are related with abnormalities in these laboratory and clinical parameters.

Conclusion: VDD is prevalent in patients with chronic liver or renal disease in Iran. There appear to be several beneficial effects of vitamin D supplementation in vitamin D deficient patients with liver or kidney disease.

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.

Vitamin D and Cardiovascular Disease: Controversy Unresolved

Vitamin D deficiency is typically caused by inadequate cutaneous synthesis secondary to decreased exposure to sunlight. Serum levels of 25-hydroxyvitamin D l <20 ng/ml are diagnostic of vitamin D deficiency. Vitamin D has various cardiovascular pleiotropic effects by activating its nuclear receptor in cardiomyocytes and vascular endothelial cells and by regulating the renin-angiotensin-aldosterone system, adiposity, energy expenditure, and pancreatic cell activity. In humans, vitamin D deficiency is associated with the following: vascular dysfunction; arterial stiffening; left ventricular hypertrophy; and worsened metrics of diabetes, hypertension, and hyperlipidemia. It is also linked with worse cardiovascular morbidity and mortality. However, meta-analyses of vitamin D supplementation trials have failed to show clear improvements in blood pressure, insulin sensitivity, or lipid parameters, thus suggesting that the link between vitamin D deficiency and cardiovascular disease may be an epiphenomenon. Ongoing larger randomized trials will clarify whether monitoring and supplementation of vitamin D play roles in cardiovascular protection.

How canola and sunflower oils affect lipid profile and anthropometric parameters of participants with dyslipidemia

Background: Restricted intakes of saturated and trans-fatty acids and replacement with poly or monounsaturated fatty acids are emphasized in healthy diets. This study evaluates the effects of a six-month consumption of canola oil compared to sunflower oil on lipid profile and anthropometric parameters of people affected by dyslipidemia. Methods: This randomized controlled trial was conducted on 96 patients with dyslipidemia, who were randomly assigned into canola oil or the sunflower oil groups. The participants were instructed to record the contents of their daily meals, beverages, fruits, and snacks a day before treatment, at the second clinic visit, in the third month, and at the end of study (i.e., six months). Lipid profile and anthropometric parameters were compared between the two groups. Student t-test or Mann Whitney U test was used for statistical comparisons of variables between groups. Multivariate analysis was performed to adjust the confounding factor effects. Results: Of the enrolled participants, 44 (45.8%) were on sunflower oil diet and 52 (54.2%) on canola oil diet. We observed no change in anthropometric parameters and thus no significant difference between the two groups (p>0.05). Significant reductions in LDL-C (p<0.001), total cholesterol (p<0.001) and triglyceride levels (p<0.001), and significant elevation in HDL-C (p=0.008) were observed in canola oil group, as well as those who used sunflower oil. Conclusion: Dietary fats in the form of canola oil or sunflower oil effectively lower the serum cholesterol, LDL-C and triglyceride concentrations. They also result in an increase in serum concentration of HDL-C. These oils, however, did not modify general anthropometric parameters.

Systematic review and meta-analysis of randomised controlled trials testing the effects of vitamin C supplementation on blood lipids

BACKGROUND & AIMS

Randomised controlled trials (RCTs) in humans revealed contradictory results regarding the effect of vitamin C supplementation on blood lipids. We aimed to conduct a systematic review and meta-analysis of RCTs investigating the effect of vitamin C supplementation on total cholesterol, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C) and triglycerides and to determine whether the effects are modified by the participants' or intervention characteristics.

METHODS

Four databases (PubMed, Embase, Scopus and Cochrane Library) were searched from inception until August 2014 for RCTs supplementing adult participants with vitamin C for ≥ 2 weeks and reporting changes in blood lipids.

RESULTS

Overall, vitamin C supplementation did not change blood lipids concentration significantly. However, supplementation reduced total cholesterol in younger participants (≤52 years age) (-0.26 mmol/L, 95% CI: -0.45, -0.07) and LDL-C in healthy participants (-0.32 mmol/L, 95% CI: -0.57, -0.07). In diabetics, vitamin C supplementation reduced triglycerides significantly (-0.15 mmol/L, 95% CI: -0.30, -0.002) and increased HDL-C significantly (0.06 mmol/L, 95% CI: 0.02, 0.11). Meta-regression analyses showed the changes in total cholesterol (β: -0.24, CI: -0.36, -0.11) and in triglycerides (β: -0.17, CI: -0.30, -0.05) following vitamin C supplementation were greater in those with higher concentrations of these lipids at baseline. Greater increase in HDL-C was observed in participants with lower baseline plasma concentrations of vitamin C (β: -0.002, CI: -0.003, -0.0001).

CONCLUSIONS

Overall, vitamin C supplementation had no significant effect on lipid profile. However, subgroup and sensitivity analyses showed significant reductions in blood lipids following supplementation in sub-populations with dyslipidaemia or low vitamin C status at baseline. PROSPERO Database registration: CRD42014013487, http://www.crd.york.ac.uk/prospero/.

Vitamin D and cardiovascular disease: is the evidence solid?

Vitamin D deficiency, prevalent in 30-50% of adults in developed countries, is largely due to inadequate cutaneous production that results from decreased exposure to sunlight, and to a lesser degree from low dietary intake of vitamin D. Serum levels of 25-hydroxyvitamin D (25-OH D) <20 ng/mL indicate vitamin D deficiency and levels >30 ng/mL are considered optimal. While the endocrine functions of vitamin D related to bone metabolism and mineral ion homoeostasis have been extensively studied, robust epidemiological evidence also suggests a close association between vitamin D deficiency and cardiovascular morbidity and mortality. Experimental studies have demonstrated novel actions of vitamin D metabolites on cardiomyocytes, and endothelial and vascular smooth muscle cells. Low 25-OH D levels are associated with left ventricular hypertrophy, vascular dysfunction, and renin-angiotensin system activation. Despite a large body of experimental, cross-sectional, and prospective evidence implicating vitamin D deficiency in the pathogenesis of cardiovascular disease, a causal relationship remains to be established. Moreover, the cardiovascular benefits of normalizing 25-OH D levels in those without renal disease or hyperparathyroidism have not been established, and questions of an epiphenomenon where vitamin D status merely reflects a classic risk burden have been raised. Randomized trials of vitamin D replacement employing cardiovascular endpoints will provide much needed evidence for determining its role in cardiovascular protection.

Influence of vitamin D supplementation on plasma lipid profiles: a meta-analysis of randomized controlled trials

Observational studies have shown that low serum levels of vitamin D have been associated with an atherogenic lipid profile. However, the intervention studies gave divergent results. We conducted a meta-analysis of randomized controlled trials that evaluated the effects of vitamin D supplementation on blood lipids. A systematic literature search was conducted via MEDLINE, Cochrane library, and EMBASE for randomized controlled clinical trials assessing the effects of vitamin D supplementation on lipids. The mean change in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG) from baseline was treated as a continuous variable. In all, 12 clinical trials consisting of 1346 participants were included in the analysis. The pooled estimate of effect for vitamin D supplementation on LDL-C was 3.23 mg/dl (95% confidence interval, 0.55 to 5.90 mg/dl). No statistically significant effects for vitamin D supplementation were observed for TC, HDL-C and TG (differences in means were 1.52 mg/dl (-1.42 to 4.46 mg/dl), -0.14 mg/dl (-0.99 to 0.71 mg/dl) and -1.92 mg/dl (-7.72 to 3.88 mg/dl) respectively). The lipid modulating effects of vitamin D supplementation should be further investigated though large-scale, randomized trials with adequate doses which can effectively elevated the active form of vitamin D in plasma and with proper population which has hyperlipemia as an inclusion criterion.

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

BACKGROUND

Our 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.

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 randomised 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 minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Seventy-eight randomised 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 I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial 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.

Modulation of vitamin D signaling is a potential therapeutic target to lower cardiovascular risk in chronic kidney disease

While it is true that many traditional cardiovascular risk factors are amenable to intervention in chronic kidney disease (CKD), the results of intervention may not be as efficacious as those obtained in the general population. Thus, there may also be a unique milieu established in CKD, which causes excess cardiovascular disease (CVD) burden by mechanisms that are as yet not fully recognized. Recently, vitamin D has sparked widespread interest because of its potential favorable benefits on CVD. However, the mechanisms for how vitamin D may improve CVD risk markers and outcomes have not been fully elucidated. Furthermore, hypovitaminosis D is highly prevalent in the CKD cohort. Given this background, we hypothesize that low vitamin D status may act as a new CVD risk marker, and modulation of vitamin D signaling may be a potential therapeutic target to lower cardiovascular risk in CKD. The data presented in this review support that the low vitamin D status may be linked with the high cardiovascular risk in CKD, based on both the biological effects of vitamin D itself on the cardiovascular system, and the cross-actions between vitamin D signaling and the multiple metabolic pathways. Considering the high prevalence of hypovitaminosis D, limited natural vitamin D food sources, and reduced sun exposure in CKD patients, recommendations for treatment of hypovitaminosis D mainly focus on exogenous supplementation with vitamin D and its analogues. Although promising, when to start therapy, the route of administration, the dose, and the duration remain need to be discussed.

Vitamin D and cardiovascular outcomes: a systematic review and meta-analysis

CONTEXT

Several studies found association between vitamin D levels and hypertension, coronary artery calcification, and heart disease.

OBJECTIVE

The aim of this study was to summarize the evidence on the effect of vitamin D on cardiovascular outcomes.

DESIGN AND METHODS

We searched electronic databases from inception through August 2010 for randomized trials. Reviewers working in duplicate and independently extracted study characteristics, quality, and the outcomes of interest. Random-effects meta-analysis was used to pool the relative risks (RR) and the weighted mean differences across trials.

RESULTS

We found 51 eligible trials with moderate quality. Vitamin D was associated with nonsignificant effects on the patient-important outcomes of death [RR, 0.96; 95% confidence interval (CI), 0.93, 1.00; P = 0.08], myocardial infarction (RR, 1.02; 95% CI, 0.93, 1.13; P = 0.64), and stroke (RR, 1.05; 95% CI, 0.88, 1.25; P = 0.59). These analyses were associated with minimal heterogeneity. There were no significant changes in the surrogate outcomes of lipid fractions, glucose, or diastolic or systolic blood pressure. The latter analyses were associated with significant heterogeneity, and the pooled estimates were trivial in absolute terms.

CONCLUSIONS

Trial data available to date are unable to demonstrate a statistically significant reduction in mortality and cardiovascular risk associated with vitamin D. The quality of the available evidence is low to moderate at best.

Lipid management in chronic kidney disease, hemodialysis, and transplantation

Recent studies have shown the spectrum of dyslipidemia in patients who have chronic kidney disease (CKD) or end-stage renal disease to be different from that of the general population. This article discusses the pathophysiology of dyslipidemia in CKD, dialysis, and renal transplant patients, the therapeutic options, and their association with clinical outcomes. Whenever possible, comparisons are made to outcomes in the general population.

Alpha-tocopherol supplementation decreases electronegative low-density lipoprotein concentration [LDL(-)] in haemodialysis patients

BACKGROUND

Oxidative stress is a significant contributor to cardiovascular diseases (CVD) in haemodialysis (HD) patients, predisposing to the generation of oxidized low-density lipoprotein (oxLDL) or electronegatively charged LDL subfraction. Antioxidant therapy such as alpha-tocopherol acts as a scavenger of lipid peroxyl radicals attenuating the oxidative stress, which decreases the formation of oxLDL. The present study was designed to investigate the influence of the alpha-tocopherol supplementation on the concentration of electronegative low-density lipoprotein [LDL(-)], a minimally oxidized LDL, which we have previously described to be high in HD patients.

METHODS

Blood samples were collected before and after 120 days of supplementation by alpha-tocopherol (400 UI/day) in 19 stable HD patients (50 +/- 7.8 years; 9 males). The concentrations of LDL(-) in blood plasma [using an anti-LDL- human monoclonal antibody (mAb)] and the anti-LDL(-) IgG auto-antibodies were determined by ELISA. Calculation of body mass index (BMI) and measurements of waist circumference (WC), triceps skin folds (TSF) and arm muscle area (AMA) were performed.

RESULTS

The plasma alpha-tocopherol levels increased from 7.9 microM (0.32-18.4) to 14.2 microM (1.22-23.8) after the supplementation (P = 0.02). The mean concentration of LDL(-) was reduced from 570.9 microg/mL (225.6-1241.0) to 169.1 microg/mL (63.6-621.1) (P < 0.001). The anti-LDL(-) IgG auto-antibodies did not change significantly after the supplementation. The alpha-tocopherol supplementation also reduced the total cholesterol and LDL-C levels in these patients, from 176 +/- 42.3 mg/dL to 120 +/- 35.7 mg/dL (P < 0.05) and 115.5 +/- 21.4 mg/dL to 98.5 +/- 23.01 mg/dL (P < 0.001), respectively.

CONCLUSION

The oral administration of alpha-tocopherol in HD patients resulted in a significant decrease in the LDL(-), total cholesterol and LDL-C levels. This effect may favour a reduction in cardiovascular risk in these patients, but a larger study is required to confirm an effect in this clinical setting.

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

BACKGROUND

Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival.

OBJECTIVES

To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials.

SEARCH STRATEGY

We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials).

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.

Vitamin D deficiency is associated with the metabolic syndrome in morbid obesity

BACKGROUND & AIMS

Vitamin D deficiency has been recently associated with the metabolic syndrome. However, it is not known whether this possible association of vitamin D deficiency with the metabolic syndrome is still present at very high degrees of obesity, as in morbidly obese patients.

METHODS

Transversal, observational study that included 73 consecutive morbidly obese patients (body mass index 40 kg/m(2)). In every patient, anthropometric variables were recorded, fasting blood was assayed for 25-hydroxyvitamin D concentrations, lipid profiles, glucose and insulin levels, and insulin resistance was estimated by homeostasis model assessment.

RESULTS

Vitamin D deficiency was present in 37 of the 73 patients (50.7%). As defined by revised Adult Treatment Panel III criteria, 46 of the 73 obese patients (63%) had the metabolic syndrome. Vitamin D deficiency was more prevalent in morbidly obese patients presenting with the metabolic syndrome, compared with those who did not achieve the criteria for this syndrome (60.9% vs. 33.3% respectively, P = 0.023). When serum concentrations of 25-hydroxyvitamin D were categorized in tertiles, there was an association of the prevalence of the metabolic syndrome with the former (P = 0.038). Serum high-density lipoprotein cholesterol concentrations were lower (37.0+/-7.8 mg/dl vs. 44.9+/-8.7 mg/dl, P = 0.003), and triglycerides levels were higher (163.3+/-81.5 mg/dl vs. 95.1+/-24.2 mg/dl, P = 0.001) in the vitamin D-deficient group.

CONCLUSION

Vitamin D deficiency is associated with the metabolic syndrome in morbidly obese patients.

Endocrinology and Dialysis: Management of Lipid Abnormalities Associated with End-Stage Renal Disease

The management of lipid abnormalities in patients with end-stage renal disease (ESRD) remains controversial. Large, well-designed studies investigating the effects of dyslipidemia on cardiovascular (CV) morbidity and mortality and the role of cholesterol lowering drugs in reducing mortality in ESRD patients are lacking. While it seems reasonable to suspect that dyslipidemia and its treatment in ESRD patients will affect CV morbidity and mortality similar to that in the general population, recent studies have suggested that this may not be the case. Furthermore, the pharmacokinetics of lipid lowering drugs are altered in patients with ESRD and must be considered when treating this group of patients. This article reviews the major classes of drugs used to treat dyslipidemia, emphasizing their role in patients with ESRD.

Improved Detection of Urothelial Carcinoma In Situ With Hexaminolevulinate Fluorescence Cystoscopy

PURPOSE

In this European multicenter study we compared hexaminolevulinate (HAL) fluorescence cystoscopy and standard white light cystoscopy for the detection of carcinoma in situ (CIS) in patients suspected of having high risk bladder cancer.

MATERIALS AND METHODS

This study was a prospective controlled, within-patient comparison of standard and HAL fluorescence cystoscopy. Eligible patients received an intravesical instillation of 50 ml HAL 8 mM solution. Cystoscopy was performed using a D light system, which provided white and blue light at 375 to 440 nm. The bladder wall was inspected and mapped, first under white light, followed by blue light. All tumors and suspicious areas identified under white light and by red fluorescence were resected or biopsied. Histological findings were assessed by an independent central pathologist blinded to the identity of the biopsies.

RESULTS

Of 211 evaluable patients 83 (39%) had CIS, of whom 18 (22%) were detected by HAL cystoscopy only, 62 (75%) were detected by standard and HAL cystoscopy, 2 (2%) were detected by standard cystoscopy only and 1 (1%) was detected by nonguided biopsy. Therefore, HAL cystoscopy identified 28% more patients with CIS than standard cystoscopy. The side effects of HAL instillation were negligible and no unexpected events were reported.

CONCLUSIONS

HAL fluorescence cystoscopy improves the detection of bladder CIS significantly, which has consequences for clinical management and may improve the patient prognosis. The procedure is easily implemented as an adjunct to standard cystoscopy and it adds no significant risk of complications.

Congestive heart failure in patients with chronic kidney disease and on dialysis

CHF is highly prevalent in ESRD and is a leading cause of death in such patients. Hypertension, renal anemia, and comorbid conditions such as coronary artery disease are particularly important risk factors for CHF in ESRD. Dialysis hypotension may be a marker of poor prognosis in such persons. Recent studies suggest that lipid peroxidation and L-carnitine deficiency may contribute to CHF in some patients with ESRD. All forms of renal replacement therapy are capable of ameliorating symptoms of CHF, but their effect on cardiovascular mortality has not been firmly established. Drug therapy, particularly angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers, is under-used in patients with ESRD and CHF. Heart/kidney transplantation may be a viable option for some patients with advanced CHF and ESRD.

Effect of oral calcitriol pulse therapy on the lipid, calcium, and glucose homeostasis of hemodialysis-patients: its safety in a combination with oral calcium carbonate

OBJECTIVE

To more clearly elucidate the conflicting results that have been obtained after oral calcitriol pulse therapy on lipid, glucose, and calcium levels in hemodialysis (HD) patients, and to determine safety of oral calcitriol pulse therapy in a combination with calcium carbonate.

DESIGN

A randomized, crossover, placebo-controlled study.

SETTING

HD centers in 3 teaching university hospitals.

PATIENTS

Forty-eight chronic HD patients.

METHODS

HD patients were randomized into 2 groups. Each group (n = 24), in addition to 4.5 g calcium carbonate daily, received either oral calcitriol pulse therapy or placebo twice weekly at the end of HD, sessions for 3 months, after which the 2 therapeutic groups were crossed-over, and for an additional 3 months, the calcitriol group received placebo, and the placebo group was put on calcitriol. Serum triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), total calcium, alkaline phosphatase, proteins, phosphorus, parathyroid hormone (PTH), blood pH, and glucose were measured at random and at the end of 3 and 6 months of the trial.

RESULTS

After calcitriol therapy, triglyceride, serum PTH, total alkaline phosphatase, and fasting blood sugar significantly decreased, but total serum calcium significantly increased, whereas other examined parameters remained unchanged compared with the other groups. Calcium, phosphorus, calcium x phosphorus product, PTH levels, and all of these parameters were optimized in 18 (37.5%), 22 (45.8%), 34 (70.8%), 30 (62.5%), and 12 (%25) cases, respectively, in the calcitriol groups. No significant side effect was seen during the trial.

CONCLUSION

Our findings indicate that short-term oral calcitriol pulse therapy in combination with calcium carbonate is safe and beneficial for metabolic abnormalities of HD patients; however, its safety for prolonged therapy is yet to be proved.

Alpha-tocopherol protects against diet induced atherosclerosis in New Zealand white rabbits

In this study, we asked the question "does alpha-tocopherol supplementation prevent an increase in total plasma cholesterol (TPC) concentration and reduce the deposition of cholesterol in arterial plaques of rabbits fed atherogenic diets?" Isocaloric diets containing 0.1% cholesterol to induce atherosclerosis were enriched in one of three fats: saturated fats (SAT), monounsaturated fats (MONO), or n-6 polyunsaturated fats (POLY). Half of each of the three diets were supplemented with 2,500 IU alpha-tocopherol/kg-diet. Unsupplemented diets contained 25 IU alpha-tocopherol/kg-diet. Rabbits supplemented with alpha-tocopherol had plasma alpha-tocopherol concentrations 10-fold higher and an average TPC concentration 31% lower, P = 0.017, than rabbits fed unsupplemented diets. Among the three fat-fed groups, the difference was greatest for the POLY fat fed group (54%, P = 0.041). POLY fat-fed rabbits without alpha-tocopherol supplementation had plasma HDL cholesterol concentrations that were less than half that of rabbits fed other fats, P < or = 0.0001. In general, differences in mean esterified artery cholesterol concentrations among the three fat-fed groups, with and without alpha-tocopherol supplementation, paralleled differences in TPC concentration among the groups. This study suggests that for rabbits fed high pharmacological doses of alpha-tocopherol, atherosclerosis can be diminished in situations where the plasma cholesterol concentrations are also significantly lower.

Fluorescence detection of bladder cancer: a review

An effective therapeutic outcome in the treatment of bladder cancer is largely defined by its early detection. In this context, big expectations have been placed on the fluorescence-guided diagnosis of bladder cancer. This paper reviews the applications of endo- and exogenous fluorescence for early diagnosis of in situ carcinoma of the bladder. Despite certain advantages of autofluorescence, exogenous fluorescence, based on the intravesical instillation of fluorophores with the following visible light excitation, has been shown to be more effective in terms of sensitivity and specificity for detecting carcinoma in situ. The equipment consists of a slightly modified light source in order to choose between white (conventional endoscopy) or blue light (fluorescence endoscopy) excitation, and specific lenses, in order to enhance maximally the contrast between normal (blue) autofluorescence and red fluorescence from malignancies. Among exogenous fluorophores, a particular emphasis will be put on the 5-aminolevulinic acid (ALA), its ester derivative (h-ALA) and hypericin. These dyes demonstrated an excellent sensitivity above 90% and specificity ranging from 70% to 90%.

A new approach to classifying malnutrition in the hemodialysis patient

BACKGROUND

Novel classification nomenclature defining the type of malnutrition by the root cause of the hypoalbuminenia has been developing in the literature since 1999. As the classification of malnutrition became more definite in the literature, the need to assess the type of malnutrition, thereby the root cause(s) and initiate appropriate intervention(s), has become apparent.

METHODS

In September 1999, San Diego Dialysis began a continuous quality improvement (CQI) project to assess the root causes of hypoalbuminemia for patients with serum albumin level <3.5 g/dL. An extensive review of the literature was conducted on the subject of malnutrition, inflammation, and the acute-phase reaction.

FINDINGS

Two major groups of patients emerged: those consuming adequate protein and calories, yet presenting with hypoalbuminemia, and those suffering from a protein calorie deficit. Observation of the second group showed that although the monthly percentage of patients with hypoalbuminemia remained fairly constant, the names on the list changed from month to month.

CONCLUSIONS

The CQI team developed a protocol and a unique nomenclature to classify the types of malnutrition, type I, type IIa, type IIb, or mixed, by adapting the definitions in the literature through clinical practice. Interventions were developed to address each classification of malnutrition.

A randomized, double-blind, placebo-controlled trial of supplementary vitamins E, C and their combination for treatment of haemodialysis cramps

BACKGROUND

Muscle cramps that improve after carnitine or vitamin E therapies are common in haemodialysis (HD) patients. Because vitamin C participates in carnitine biosynthesis, and its levels are reduced in uraemia, subclinical vitamin C depletion may contribute to HD cramps. Our aim was to determine the effects of vitamins C, E and their combination on the frequency and intensity of HD cramps.

METHODS

In this placebo-controlled, double-blind study, 60 HD-patients were randomized into four therapeutic groups. Each group (n=15) received six identical capsules daily for 8 weeks, containing one of the following: vitamin E (400 mg), vitamin C (250 mg), their combination, or placebo.

RESULTS

The frequency and intensity of HD cramps decreased significantly in all three vitamin groups compared with the placebo group at the end of the trial, and compared with the pre-treatment values. At the end of the trial, vitamins E, C, their combination, and placebo produced cramp reductions of 54, 61, 97 and 7%, respectively. The percentage cramp reduction had no significant correlation with age, sex, aetiology of end-stage renal disease, serum electrolytes or HD duration, but showed a positive correlation (r=0.33, P=0.01) with the type of therapy. No vitamin-related adverse effects were encountered during the trial.

CONCLUSION

Short-term treatment with the combination of vitamins E and C is safe and effective in reducing HD cramps; however, its safety for prolonged therapy has yet to be evaluated in HD patients.

Involvement of oxidation-sensitive mechanisms in the cardiovascular effects of hypercholesterolemia

Hypercholesterolemia is a common clinical metabolic and/or genetic disorder that promotes functional and structural vascular wall injury. The underlying mechanisms for these deleterious effects involve a local inflammatory response and release of cytokines and growth factors. Consequent activation of oxidation-sensitive mechanisms in the arterial wall, modulation of intracellular signaling pathways, increased oxidation of low-density lipoprotein cholesterol, and quenching of nitric oxide can all impair the functions controlled by the vascular wall and lead to the development of atherosclerosis. This cascade represents a common pathological mechanism activated by various cardiovascular risk factors and may partly underlie synergism among them as well as the early pathogenesis of atherosclerosis. Antioxidant intervention and restoration of the bioavailability of nitric oxide have been shown to mitigate functional and structural arterial alterations and improve cardiovascular outcomes. Elucidation of the precise nature and role of early transductional signaling pathways and transcriptional events activated in hypercholesterolemia in children and adults, including mothers during pregnancy, and understanding their downstream effects responsible for atherogenesis may help in directing preventive and interventional measures against atherogenesis and vascular dysfunction.