Zinc supplementation alters plasma aluminum and selenium status of patients undergoing dialysis: a pilot study

Effect of Selenium and Zinc Supplementation on Reproductive Organs Following Postnatal Protein Malnutrition

Protein diets are required for the normal development of the reproductive system and their inadequacy or deficiency might have hazardous functional complications during maturational and developmental stages. The study was carried out to evaluate the effect of selenium (Se) and zinc (Zn) supplementation on the male and female reproductive organs of rats with postnatal protein malnutrition. Male and female weanling rats were randomly assigned to six groups respectively. The adequate protein diet rats were fed with 16% casein diet while the protein malnourished diet (PMD) rats were fed with 5% casein diet. After the 8th week of feeding, Se (sodium selenite; Na2SeO3) and Zn (zinc sulfate; ZnSO4·7H2O) were supplemented for 3 weeks. The growth curve of body weights, lipid profile, testosterone and progesterone level, Na+-K+-ATPase activity, oxidative stress, and antioxidant status were evaluated. The results showed that PMD reduced the body weights of male and female rats. It also reduced the activities of catalase and glutathione peroxidase in the testes, but reductions in superoxide dismutase and glutathione-S-transferase activities, glutathione, vitamins C and E, testosterone, and progesterone levels were observed in both the testes and ovaries. Furthermore, PMD increased the nitric oxide level in both organs and altered the plasma lipid profiles in both sexes. Se and Zn supplementation, however, restored almost all the alterations observed in all the parameters analyzed. In conclusion, Se and Zn supplementation protects the male and female reproductive organs of rats against postnatal protein malnutrition.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

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.

Effect of Curcumin Consumption on Inflammation and Oxidative Stress in Patients on Hemodialysis: A Literature Review

Advanced chronic kidney disease (CKD) stages lead to exacerbated inflammation and oxidative stress. Patients with CKD in stage 5 need renal hemodialysis (HD) to remove toxins and waste products. However, this renal replacement therapy is inefficient in controlling inflammation. Regular curcumin consumption has been shown to reduce inflammation and oxidative stress in subjects with chronic pathologies, suggesting that the daily intake of curcumin may alleviate these conditions in HD patients. This review analyzes the available scientific evidence regarding the effect of curcumin intake on oxidative stress and inflammation in HD patients, focusing on the mechanisms and consequences of HD and curcumin consumption. The inclusion of curcumin as a dietary therapeutic supplement in HD patients has shown to control the inflammation status. However, the optimal dose and oral vehicle for curcumin administration are yet to be determined. It is important to consider studies on curcumin bioaccessibility to design effective oral administration vehicles. This information will contribute to the achievement of future nutritional interventions that validate the efficacy of curcumin supplementation as part of diet therapy in HD.

Circulatory Imbalance of Essential and Toxic Trace Elements in Pre-dialysis and Hemodialysis Patients

The status of essential and toxic trace elements in patients with different stages of chronic kidney disease (CKD) is still unclear and not well characterized. The present study examined the circulatory levels of a wide panel of trace elements (Al, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Cd, Pb, and U) in hemodialysis patients (HD group) and pre-dialysis patients with stage 3 CKD (PD group). Comparisons were made between groups of patients and healthy individuals from the control group (CG). The levels of Al, Mn, Co, Ni, Cu, As, Se, Sr, and Pb were higher, while the levels of Cr, Zn, Rb, Cd, and U were lower in HD patients than in our CG. Higher levels of Al and Se, as well as lower levels of As, Sr, Zn, Rb, and U were significant and distinguished HD from PD. Among other analyzed elements, Co, Se, and U are the only trace elements that did not distinguish PD from CG at a statistically significant level. The HD group had lower serum U levels than the PD group, and this could be a result of hemodialysis. This study also revealed that the Cu/Zn ratio could be used as a marker for early and late detection of renal failure. Marked changes of essential and toxic trace element levels in sera indicate additional pathophysiological events in CKD, which could additionally contribute to the preexisting increased morbidity of HD patients. Measurement of trace elements in HD patients should be performed routinely.

Zinc Deficient Intake in Hemodialysis Patients: A Path to a High Mortality Risk

BACKGROUND

Zinc is essential for human nutrition and plays an important role in hemodialysis (HD) patients. The aim of this study is to analyze the relationship between zinc intake and mortality in HD patients.

METHODS

This is a longitudinal, prospective, multicenter study with 582 HD patients from 37 dialysis centers. We recorded clinical and body composition parameters. Dietary intake and physical activity data were obtained using the Food Frequency Questionnaire and International Physical Activity Questionnaire. All statistical tests were performed using SPSS 24.0 software. A P value lower than 0.05 was considered statistically significant.

RESULTS

Patients' mean age was 67.8 ± 17.7 years and median HD vintage was 65 (43-104) months. About 53.6% of the patients presented a deficient daily intake of zinc. Patients with the highest zinc intake were those who had a higher lean tissue index (P = .022), energy (P < .001), and protein (p = .022) intakes. Zinc intake was positively correlated with energy (r = 0.709) and protein intake (r = 0.805) and negatively correlated with the malnutrition screening tool score (r = -0.087). A higher energy, protein, and lower carbohydrates intake, as well as lower HD vintage and higher lean tissue index were predictors of zinc intake. A higher mortality risk was observed in patients with zinc intake below the recommended values, even after the adjustment for age, presence of diabetes, gender, dialysis vintage, albumin, lean tissue index, energy intake/kilogram, and level of physical activity (P = .021).

CONCLUSION

There is a high prevalence of HD patients with an inadequate zinc intake, which is related to worse nutritional and body composition parameters and with a higher mortality risk.

Beneficial effects of Se/Zn co-supplementation on body weight and adipose tissue inflammation in high-fat diet-induced obese rats

This research investigated the effect of co-supplementation of selenium with zinc on weight control and the inflammatory and oxidative status in relation to obesity. Male Wistar rats (N = 32) were randomly divided into four groups after induction of obesity model: 1) "Zn" was supplemented with zinc sulfate (15 mg/kg BW), 2) "Se" supplemented with selenium as sodium selenate (0.5 mg/kg BW), 3) "Zn + Se" which received Zn (15 mg/kg BW) + Se (0.5 mg/kg BW), and 4) "HFD" as the control group. The intervention was done for eight weeks. At the end of treatment, serum and tissue level of Zn, Se, SOD, GSH-Px, MDA, leptin, TNF-α, and IL-6 was evaluated. Weight and food intake were significantly reduced in the Se group(p < .001), while in the Zn group, weight gain due to obesity was prevented compared to the control group (p = .48). There was a significant and stronger increase in SOD, GSH-Px levels and a remarkable decrease in MDA, leptin, TNF-α, and IL-6 in the group receiving the combination of two supplements than either alone(p < .001). Leptin had a positive correlation with inflammatory factors and lipid peroxidation marker and showed an inverse relationship with Zn and Se levels and anti-oxidative enzymes(p < .05). The analysis showed the mediating role of leptin in the effects of zinc. Co-supplementation of selenium and zinc may have a synergistic effect in reduction of oxidative and inflammatory markers. Regarding the effect of zinc on inflammatory factors and lipid peroxidation, leptin can play a mediating role.

Effects of Chronic Aluminum Lactate Exposure on Neuronal Apoptosis and Hippocampal Synaptic Plasticity in Rats

This study investigated the effects of chronic aluminum exposure on apoptosis of hippocampal neurons, and synaptic plasticity in the hippocampus in rats. Rats were divided into the control, low-dose (L-Al), mid-dose (M-Al), and high-dose (H-Al) groups. After chronic exposure of aluminum, the Morris water maze (MWM) and open-field (OF) tests were performed to assess the behavioral performance. Electrophysiological measurements were conducted. Flow cytometry was used to assess the apoptotic processes. Quantitative real-time PCR and ELISA were performed to measure mRNA and protein expression levels of caspases. After 90 days of aluminum exposure, the aluminum contents in the brain of the rats were increased, with the increasing exposure dose. The MWM and OF tests showed that chronic exposure of aluminum significantly impaired the neurobehavior of rats. Moreover, after high-frequency stimulation (HFS), the average amplitudes of field excitatory postsynaptic potentials (fEPSPs) for the M-Al and H-Al groups were lower than the control group at 10, 20, 30, 40, 50, and 60 min. Furthermore, the apoptotic rates in the M-Al and H-Al groups were significantly higher than the control group. The qRT-PCR and ELISA showed that, compared with the control group, the mRNA and protein expression levels of caspases-3, -8, and -9 were significantly increased in the aluminum-treated groups compared with the control group. Long-term exposure to aluminum could induce the apoptosis of hippocampal neurons, damage the synaptic plasticity, and impair the learning and memory functions in rats. There might be a close relationship between the neuronal apoptosis and synaptic plasticity damage.

The Effect of Zinc Supplementation on Steatosis Severity and Liver Function Enzymes in Overweight/Obese Patients with Mild to Moderate Non-alcoholic Fatty Liver Following Calorie-Restricted Diet: a Double-Blind, Randomized Placebo-Controlled Trial

The role of zinc is known in balancing the oxidant/antioxidant system and also in improving insulin resistance in many diseases. Recently, in vivo and in vitro studies revealed roles of zinc on lipophagy and suppressing hepatic lipid deposition. The present study is the first double-blind randomized clinical trial that investigated the effect of zinc supplement on clinical manifestations and anthropometric parameters of overweight/obese non-alcoholic fatty liver patients following calorie-restricted diet. Fifty-six overweight/obese subjects with confirmed non-alcoholic fatty liver disease (NAFLD) using ultrasonography were randomized to treatment (calorie-restricted diet plus 30 mg/day zinc supplement) or placebo (calorie-restricted diet and placebo) groups. Serum liver enzymes and liver steatosis were measured at the baseline and 12 weeks post-intervention. Anthropometric measurements and food recalls were collected at the beginning, weeks 6 and 12. Zinc supplementation significantly elevated serum zinc concentrations in the treatment group (p < 0.001). Treatment also reduced alanine aminotransferase and γ-glutamyl transpeptidase enzymes in the treatment group (p < 0.05). Waist circumference was also significantly lowered in the zinc group (p < 0.05). Liver steatosis and fatty liver index changes were not significant between the groups. Overall, beneficial effects of zinc supplementation were shown on serum levels of zinc and liver enzymes in overweight/obese NAFLD patients.

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.

Zinc Plasma Status and Sensory Perception in Nondialysis Chronic Kidney Disease Patients

OBJECTIVE

The aim of this study was to evaluate the association between zinc plasma levels and sensory perception in patients with chronic kidney disease (CKD).

METHODS

A cross-sectional study with 21 nondialysis CKD patients (11 men, 51.1 ± 7.1 years, body mass index 27.9 ± 7.1 kg/m², estimated glomerular filtration rate 32.7 ± 19.9 mL/min) and 22 non-CKD volunteers (10 men, 49.8 ± 8.3 years, body mass index 28.5 ± 5.4 kg/m²) was conducted. Blood samples were collected to obtain plasma for zinc analysis. Anthropometric and biochemical parameters, as well as food intake and salivary flow rate, were also evaluated. Taste sensory perception for sweet, acidic, bitter, and salty flavors was determined by the "three-drop method," with 4 concentrations of the 4 basic tastes.

RESULTS

As expected, zinc plasma levels were significantly lower in CKD patients (70.1 ± 19.2ug/dL) when compared with the control group participants (123.2 ± 24.6 μg dL) (P ˂ .0001). The bitter taste perception was lower in the CKD group (p˂0.0001). Our findings showed that sensitivity to sour (P = .047), salty (P = .03), and bitter tastes was significantly lower in participants with lower zinc plasma levels. Also, bitter taste sensitivity was lower in participants with less zinc intake (P = .038). When grouping control subjects and CKD patients, significant correlations were observed between zinc plasma levels and the number of correct answers for bitter taste (r = 0.49, P = .001), number of correct answers for salty taste (r = 0.30, P = .048), and total score of correct answers (r = 0.30, P = .044).

CONCLUSIONS

Reduced zinc plasma levels in nondialysis CKD patients may be associated with lower perception of bitter, sour, and salty tastes and strategies to restore these levels are crucial due many factors, including food preferences and intake.

Antioxidant Supplementation in Renal Replacement Therapy Patients: Is There Evidence?

The disruption of balance between production of reactive oxygen species and antioxidant systems in favor of the oxidants is termed oxidative stress (OS). To counteract the damaging effects of prooxidant free radicals, all aerobic organisms have antioxidant defense mechanisms that are aimed at neutralizing the circulating oxidants and repair the resulting injuries. Antioxidants are either endogenous (the natural defense mechanisms produced by the human body) or exogenous, found in supplements and foods. OS is present at the early stages of chronic kidney disease, augments progressively with renal function deterioration, and is further exacerbated by renal replacement therapy. End-stage renal disease patients, on hemodialysis (HD) or peritoneal dialysis (PD), suffer from accelerated OS, which has been associated with increased risk for mortality and cardiovascular disease. During HD sessions, the bioincompatibility of dialyzers and dialysate trigger activation of white blood cells and formation of free radicals, while a significant loss of antioxidants is also present. In PD, the bioincompatibility of solutions, including high osmolality, elevated lactate levels, low pH, and accumulation of advanced glycation end-products trigger formation of prooxidants, while there is significant loss of vitamins in the ultrafiltrate. A number of exogenous antioxidants have been suggested to ameliorate OS in dialysis patients. Vitamins B, C, D, and E, coenzyme Q10, L-carnitine, a-lipoic acid, curcumin, green tea, flavonoids, polyphenols, omega-3 polyunsaturated fatty acids, statins, trace elements, and N-acetylcysteine have been studied as exogenous antioxidant supplements in both PD and HD patients.

Increased Serum Al Levels in Hemodialysis Patients Kept Enhanced during a 2-Year Prospective Study

The regulation of mineral homeostasis is altered in hemodialysis patients with renal insufficiency, producing increased risk for secondary diseases like cardiovascular ones. We hypothesized that risen serum aluminum (Al) concentration in hemodialysis patients kept enhanced during a 2-year longitudinal study is associated with enhanced cardiovascular risk and influenced by medical treatments. This study reports the prospective monitoring of serum Al levels in six-monthly samplings over 2 years in 116 hemodialysis patients and a control group of 50 healthy adults. The influence of other factors like sex, age, kidney transplant, disease etiology, and drug consumption was also considered. At each sampling, serum Al levels were significantly higher in the patients than in the healthy controls (P < 0.05). Levels in the patient group were statistically significantly lower at the third and fourth versus first and second samplings, which may be related to Al accumulation in tissues. Increased Al levels in patients were positively and significantly related to serum calcium (Ca) and uric acid levels. Serum Al concentrations were significantly lower in patients receiving vasodilators and diuretics. Higher serum Al levels in hemodialyzed patients administered with phosphate binders or anti-hyperkalemics are attributable to their usual Al salt content. The consumption of antianemic drugs increases Al absorption by forming more bioavailable complexes with the compounds in these drugs. In conclusion, this is the first study to indicate that cardiovascular problems associated with elevated serum Al levels in hemodialysis patients may be in part mitigated by administrating vasodilators and diuretics, which reduce these levels.

Comparative Study on Trace Element Excretions between Nonanuric and Anuric Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

Few studies have been reported on alterations of trace elements (TE) in peritoneal dialysis patients. Our objective was to investigate and assess the characteristics of daily TE excretions in continuous ambulatory peritoneal dialysis (CAPD) patients. This cross-sectional study included 61 CAPD patients (nonanuric/anuric: 45/16) and 11 healthy subjects in Wuhan, China between 2013 and 2014. The dialysate and urine of patients and urine of healthy subjects were collected. The concentrations of copper (Cu), zinc (Zn), selenium (Se), molybdenum (Mo), and arsenic (As) in dialysate and urine were determined using inductively coupled plasma mass spectrometer (ICP-MS). Various clinical variables were obtained from automatic biochemical analyzer. Daily Cu, Zn, Se, and Mo excretions in nonanuric patients were higher than healthy subjects, while arsenic excretion in anuric patients was lower. A strong and positive correlation was observed between Se and Mo excretion in both dialysate (β = 0.869, p < 0.010) and urine (β = 0.968, p < 0.010). Furthermore, the clinical variables associated with Se excretion were found to be correlated with Mo excretion. Our findings indicated that nonanuric CAPD patients may suffer from deficiency of some essential TEs, while anuric patients are at risk of arsenic accumulation. A close association between Se and Mo excretion was also found.

Systemic Redox Imbalance in Chronic Kidney Disease: A Systematic Review

Patients with chronic kidney disease (CKD) experience imbalance between oxygen reactive species (ROS) production and antioxidant defenses leading to cell and tissue damage. However, it remains unclear at which stage of renal insufficiency the redox imbalance becomes more profound. The aim of this systematic review was to provide an update on recent advances in our understanding of how the redox status changes in the progression of renal disease from predialysis stages 1 to 4 to end stage 5 and whether the various treatments and dialysis modalities influence the redox balance. A systematic review was conducted searching PubMed and Scopus by using the Cochrane and PRISMA guidelines. In total, thirty-nine studies met the inclusion criteria and were reviewed. Even from an early stage, imbalance in redox status is evident and as the kidney function worsens it becomes more profound. Hemodialysis therapy per se seems to negatively influence the redox status by the elevation of lipid peroxidation markers, protein carbonylation, and impairing erythrocyte antioxidant defense. However, other dialysis modalities do not so far appear to confer advantages. Supplementation with antioxidants might assist and should be considered as an early intervention to halt premature atherogenesis development at an early stage of CKD.

Ascorbate- and zinc-responsive parkinsonism

OBJECTIVE

To report a case of Parkinsonism rapidly responsive to intravenous replacement of vitamin C and zinc.

CASE SUMMARY

A 66-year-old man with Parkinsonism, pleural effusion, and bipolar disorder was found to have low serum vitamin C and zinc levels. Intravenous replacement of these micronutrients led to resolution of the movement disorder in less than 24 hours.

DISCUSSION

Parkinsonism has been associated with vitamin C deficiency, and recent cases of scurvy complicated by Parkinsonism have responded well to intravenous replacement of vitamin C. In this case, deficiency of zinc may have contributed to the development of a movement disorder. The likely pathophysiology of, and treatment recommendations for, Parkinsonism linked to deficiencies of vitamin C and zinc are reviewed.

CONCLUSIONS

Whereas vitamin C has a strong link with Parkinsonism, the potential role of zinc has only been suspected. This case report highlights some of the potential links between zinc deficiency and Parkinsonism.

Chronic kidney disease: considerations for nutrition interventions

Chronic kidney disease (CKD) is highly prevalent and has major health consequences for patients. Caring for patients with CKD requires knowledge of the food supply, renal pathophysiology, and nutrition-related medications used to work synergistically with diet to control the signs and symptoms of the disease. The nutrition care process and International Dietetic and Nutrition Terminology allow for systematic, holistic, quality care of patients with this complex, progressive disease. Nutrition interventions must be designed with the individual patients needs in mind while prioritizing factors with the largest negative impact on health outcomes and mortality risk. New areas of nutrition treatment are emerging that involve a greater focus on micronutrient needs, the microbiome, and vegetarian-style diets. These interventions may improve outcomes by decreasing inflammation, improving energy and protein delivery, and lowering phosphorus, electrolytes, and fluid retention.