Can Outcomes be Improved in Dialysis Patients by Optimizing Trace Mineral, Micronutrient, and Antioxidant Status?: The Impact of Vitamins and their Supplementation

Does Vitamin Supplementation Play a Role in Chronic Kidney Disease?

Although the role of vitamins in the human body is proven, guidelines for patients with chronic kidney disease (CKD) remain unclear. This narrative review summarizes the findings of 98 studies of CKD and the effects of vitamin D, B, C, A, E, and K supplementation on patients on dialysis for CKD, with the aim of summarizing the existing guidelines. The findings are promising, showing the potential effectiveness of vitamin supplementation with, for example, vitamins B, D, or C. However, recommendations are still ambiguous, especially in the case of vitamins A and K, due to the potential toxicity associated with higher doses for patients. Continued research is needed to rigorously evaluate the effectiveness and carefully consider the potential risks of some vitamin supplementation for patients with CKD.

Demand for Water-Soluble Vitamins in a Group of Patients with CKD versus Interventions and Supplementation-A Systematic Review

BACKGROUND

Increasingly, chronic kidney disease (CKD) is becoming an inevitable consequence of obesity, metabolic syndrome, and diabetes. As the disease progresses, and through dialysis, the need for and loss of water-soluble vitamins both increase. This review article looks at the benefits and possible risks of supplementing these vitamins with the treatment of CKD.

METHODS

Data in the PubMed and Embase databases were analyzed. The keywords "chronic kidney disease", in various combinations, are associated with thiamin, riboflavin, pyridoxine, pantothenic acid, folates, niacin, cobalamin, and vitamin C. This review focuses on the possible use of water-soluble vitamin supplementation to improve pharmacological responses and the overall clinical condition of patients.

RESULTS

The mechanism of supportive supplementation is based on reducing oxidative stress, covering the increased demand and losses resulting from the treatment method. In the initial period of failure (G2-G3a), it does not require intervention, but later, especially in the case of inadequate nutrition, the inclusion of supplementation with folate and cobalamin may bring benefits. Such supplementation seems to be a necessity in patients with stage G4 or G5 (uremia). Conversely, the inclusion of additional B6 supplementation to reduce CV risk may be considered. At stage 3b and beyond (stages 4-5), the inclusion of niacin at a dose of 400-1000 mg, depending on the patient's tolerance, is required to lower the phosphate level. The inclusion of supplementation with thiamine and other water-soluble vitamins, especially in peritoneal dialysis and hemodialysis patients, is necessary for reducing dialysis losses. Allowing hemodialysis patients to take low doses of oral vitamin C effectively reduces erythropoietin dose requirements and improves anemia in functional iron-deficient patients. However, it should be considered that doses of B vitamins that are several times higher than the recommended dietary allowance of consumption may exacerbate left ventricular diastolic dysfunction in CKD patients.

CONCLUSIONS

Taking into account the research conducted so far, it seems that the use of vitamin supplementation in CKD patients may have a positive impact on the treatment process and maintaining a disease-free condition.

Water-Soluble Vitamins and Trace Elements Losses during On-Line Hemodiafiltration

Maintenance hemodialysis induces water-soluble vitamins and trace elements losses, which is why recommendations regarding potential supplementation were provided, but mainly based on conventional hemodialysis. This study′s aim was to measure the water–soluble vitamins and trace element losses during one on-line post-dilution hemodiafiltration (HDF) session. Thirty-nine patients under maintenance HDF were enrolled. We used the Theraflux^® sampler (Theradial Corp., Orvault, France) to analyze the full session dialysate mass transfer. Blood and dialysate samples were collected before and after one HDF session to measure B1, B2, B6, B9, B12, C vitamins, zinc, and selenium concentrations. Values significantly decreased for B1 (20.2%), B2 (13%), B6 (25.4%), B9 (32.6%), C (66.6%) and selenium (6.7%). No significant differences were found for vitamin B12 and zinc. The dialysate losses per session were 1.12 ± 0.88 mg for vitamin B1, 0.28 ± 0.30 mg for B2, 0.33 ± 0.09 mg for B6, 0.3 ± 0.18 mg for B9, 147.5 ± 145.50 mg for C and 25.75 ± 6.91 mg for zinc. Vitamin B12 and selenium were under detection values. In conclusion, during a standard 4hr-HDF session, we found important losses for vitamin B1, B6, B9, C and zinc, suggesting the need for regular monitoring of plasma levels and systematic supplementation of these compounds.

Herbal antioxidants in dialysis patients: a review of potential mechanisms and medical implications

The consumption of exogenous antioxidants isolated from herbal extracts has shown beneficial effects on ameliorating dialysis-related complications through debilitating oxidative stress and inflammatory process. Many clinical studies available in public databases have reported the improved consequences of dialysis in patients supplemented with herbal antioxidants. Exploration of such data offers great possibilities for gaining insights into the potential mechanisms and medical implications of herbal antioxidants. In this work, the mechanisms and implications of some famous bioactive substances including silymarin, curcumin, resveratrol, emodin, and quercetin on the consequences of dialysis in chronic kidney disease (CKD) patients were explored. The protective features of silymarin are due to the flavonoid complex silybin. Curcumin is an active element from the root of curcuma longa with extensive beneficial properties, including antioxidant, anti-inflammatory activity, and inhibitory effects on cell apoptosis. Resveratrol can reduce the oxidative stress by neutralization of free radicals. Emodin is known as a natural anthraquinone derivative isolated from Chinese herbs. Finally, quercetin has been reported to exhibit several properties including antioxidant, anti-diabetic, analgesic, antihistaminic, antiviral, cholesterol reducer, and renal hemodynamic modulator. However, potential mechanisms and medical implications of the aforementioned herbal antioxidants seem to be more complicated, that is, more studies are required in this field.

Water-Soluble Vitamin Levels and Supplementation in Chronic Online Hemodiafiltration Patients

Introduction

Supplementation of water-soluble vitamins is a common practice in hemodialysis patients, but dosages are largely based on conventional hemodialysis techniques. The aim of this study was to assess the status of water-soluble vitamins in patients on hemodiafiltration (HDF), and attempt to determine optimal dose of vitamin supplements.

Methods

This monocentric study included 40 patients on thrice-weekly chronic HDF. At baseline, all patients received 2 tablets of Dialvit containing B and C vitamins after each dialysis session. Predialysis samples of B and C vitamins were measured in both blood (n = 40) and a subgroup of dialysate (n = 6) samples. A second blood sample was obtained in 24 patients 3 months after dose adjustment of the vitamin supplement.

Results

At baseline, B-vitamin levels were high with, respectively, 0.4%, 10.0%, and 89.6% of patients in the low, normal, and high reference range. For vitamin C, most patients were in the normal range (5.0%, 82.5%, and 12.5% in low, normal, and high reference range). Three months after dose reduction, B vitamin levels decreased but stayed mostly at or above the normal range (1.4%, 25.7%, 72.9% in low, normal, and high reference range). Three patients (12.5%) developed vitamin C deficiency on low-dose substititon.

Conclusion

This study shows that the levels of most vitamins are above the normal range in patients on HDF receiving a classic dose of vitamin supplements, vitamin C excepted. Our study suggests that the classic dose of postdialysis vitamin B supplements may be reduced.

Oxidative Stress in ESRD Patients on Dialysis and the Risk of Cardiovascular Diseases

Chronic kidney disease is highly prevalent worldwide. The decline of renal function is associated with inadequate removal of a variety of uremic toxins that exert detrimental effects on cells functioning, thus affecting the cardiovascular system. The occurrence of cardiovascular aberrations in CKD is related to the impact of traditional risk factors and non-traditional CKD-associated risk factors, including anemia; inflammation; oxidative stress; the presence of some uremic toxins; and factors related to the type, frequency of dialysis and the composition of dialysis fluid. Cardiovascular diseases are the most frequent cause for the deaths of patients with all stages of renal failure. The kidney is one of the vital sources of antioxidant enzymes, therefore, the impairment of this organ is associated with decreased levels of these enzymes as well as increased levels of pro-oxidants. Uremic toxins have been shown to play a vital role in the onset of oxidative stress. Hemodialysis itself also enhances oxidative stress. Elevated oxidative stress has been demonstrated to be strictly related to kidney and cardiac damage as it aggravates kidney dysfunction and induces cardiac hypertrophy. Antioxidant therapies may prove to be beneficial since they can decrease oxidative stress, reduce uremic cardiovascular toxicity and improve survival.

Inflammation and Oxidative Stress in Chronic Kidney Disease-Potential Therapeutic Role of Minerals, Vitamins and Plant-Derived Metabolites

Chronic kidney disease (CKD) is a debilitating pathology with various causal factors, culminating in end stage renal disease (ESRD) requiring dialysis or kidney transplantation. The progression of CKD is closely associated with systemic inflammation and oxidative stress, which are responsible for the manifestation of numerous complications such as malnutrition, atherosclerosis, coronary artery calcification, heart failure, anemia and mineral and bone disorders, as well as enhanced cardiovascular mortality. In addition to conventional therapy with anti-inflammatory and antioxidative agents, growing evidence has indicated that certain minerals, vitamins and plant-derived metabolites exhibit beneficial effects in these disturbances. In the current work, we review the anti-inflammatory and antioxidant properties of various agents which could be of potential benefit in CKD/ESRD. However, the related studies were limited due to small sample sizes and short-term follow-up in many trials. Therefore, studies of several anti-inflammatory and antioxidant agents with long-term follow-ups are necessary.

Association between trace element concentrations and anemia in patients with chronic kidney disease: a cross-sectional population-based study

Anemia is common in chronic kidney disease (CKD) and may be affected by trace element concentrations. While the concentrations of trace elements are known to be altered in CKD, the relationship between trace element and hemoglobin concentrations has not been systematically investigated in a large cohort. This study aims to examine associations between trace element concentrations and anemia in patients with CKD. Data from the National Health and Nutrition Examination Survey collected from 2011 to 2014 were used for this analysis. The participants who were more than 20 years old were included. A total of 3057 participants were included; the final cohort was divided into two groups based on CKD status. The concentrations of hemoglobin, iron, zinc, and manganese were significantly lower in participants with than without CKD (all p<0.05). Multivariate analyses showed that in patients without CKD, hemoglobin concentrations correlated positively with iron, zinc, and cadmium (β=0.005, 0.009, and 0.33, respectively), but correlated negatively with copper levels (β=-0.002). In patients with CKD, hemoglobin concentrations correlated positively with cadmium and selenium, but negatively with copper levels (β=0.57, 0.007, and -0.008, respectively). The serum iron concentration was found to correlate positively with zinc, cadmium, and selenium, but negatively with copper and manganese concentrations in the total study population (all p<0.05). The associations between serum concentrations of trace elements and hemoglobin differ between patients with and without CKD. Further investigations are warranted to determine whether patients with CKD have distinct trace element requirements.

Nutritional Management for Chronic Kidney Disease Patients who Undergo Bariatric Surgery: A Narrative Review

Bariatric surgery (BS) may be effective for chronic kidney disease (CKD) patients by reducing microalbuminuria and proteinuria, and by facilitating their meeting inclusion criteria for kidney transplantation. However, nutritional management for this population is complex and specific guidelines are scarce. A literature search was performed to create dietetic practice for these patients based on the most recent evidence. For the purposes of nutritional recommendations, we divided the patients into 2 subgroups: 1) patients with CKD and dialysis, and 2) patients after kidney transplantation. Before surgery, nutritional care includes nutritional status evaluation and adjusting doses of supplements to treat deficiencies and daily nutrient intake according to the dietary restrictions derived from kidney disease, including quantities of fluids, protein, phosphorus, potassium, and vitamins. After BS, these patients are at major risk for lean body mass loss, malnutrition and dehydration because of fluid restriction and diuretics. Postoperative nutritional recommendations should be carefully tailored according to CKD nutritional limitations and include specific considerations regarding protein, fluids, and supplementation, in particular calcium, vitamin A, and vitamin D. Nutritional management of CKD and kidney transplant patients undergoing BS is challenging and future studies are required to establish uniform high-level evidence-based guidelines.

Plasma Retinol Concentration Is Mainly Driven by Transthyretin in Hemodialysis Patients

OBJECTIVE

Micronutrients deficiencies in hemodialysis patients are due to low dietary intakes and intradialytic losses for hydrophilic micronutrients. Conversely, lipophilic nondialyzable compounds might accumulate because of a lack of elimination through renal metabolism or dialysis. Other compounds have complex metabolism: their concentration is not explained by these phenomenons. The aim of this study was to report plasma concentrations of lipophilic micronutrients in hemodialysis patients and to analyze if these concentrations were predictive of mortality.

DESIGN

The design was monocentric observational longitudinal study.

SUBJECTS

A total of 123 hemodialysis patients included in this observational study.

MAIN OUTCOME MEASURE

Plasma concentration of lipophilic micronutrients retinol and its two co-transporters transthyretin and retinol-binding protein 4, tocopherol, and carotenoids (α-carotene and β-carotene, β-cryptoxanthin, lycopene, lutein, and zeaxanthin), and all factors associated with 1-year mortality.

RESULTS

Within the 123 patients of the study, median age (interquartile range) was 77.5 (69.5-84.5) years and 58.5% were male. Median retinol plasma concentration was 4.07 (2.65-5.51) μmol/L, and 91.9% of patient had high plasma retinol concentrations. In monovariate analysis, retinol levels were inversely correlated with mortality (hazard ratio = 0.57 [0.45-0.72]; P < .001). This effect remained significant after adjustment with several parameters. Nevertheless, the correlation between retinol and mortality disappeared as soon as transthyretin was added in the statistical model, suggesting an effect of transthyretin as confusing bias. Median tocopherol plasma concentration was 34.8 (28.3-42.9) μmol/L and 72.4% of patients had high plasma tocopherol concentration. Neither tocopherol plasma levels nor carotenoids concentrations were correlated with death in multivariate analysis.

CONCLUSIONS

In hemodialysis patients, the correlation between retinol plasma concentration and mortality represents the nutritional status but not a direct biological effect of retinol. Retinol is only a surrogate predictor of mortality. It might not represent vitamin A levels, but likely the transthyretin level. Plasma retinol levels should be interpreted cautiously in hemodialysis patients.

Vitamins and Microelement Bioavailability in Different Stages of Chronic Kidney Disease

Chronic kidney disease (CKD) predisposes one to either deficiency or toxic excess of different micronutrients. The knowledge on micronutrients—specifically water-soluble vitamins and trace elements—in CKD is very limited. Consequently, current guidelines and recommendations are mostly based on expert opinions or poor-quality evidence. Abnormalities of micronutrient resources in CKD develop for several reasons. Dietary restrictions and anorexia lead to an insufficient micronutrient intake, while diuretics use and renal replacement therapy lead to their excessive losses. Absorption is unpredictable, and metabolism impaired. Better understanding of the micronutrient needs of CKD patients could have an impact on many complications linked to vitamin and trace element disorders, including high mortality, increased risk of atherosclerosis, inflammation, oxidative stress, anemia, polyneuropathy, encephalopathy, weakness and fragility, muscle cramps, bone disease, depression, or insomnia. Here, we summarize the up-to-date knowledge on micronutrient resources in different stages of CKD, and share our experience with the assessment of micronutrient status.