Association of serum vitamin B12 and folate with mortality in incident hemodialysis patients

Role of Peritoneal Equilibration Test in Assessing Folate Transport During Peritoneal Dialysis

OBJECTIVES

Low plasma folate levels have been reported in patients undergoing hemodialysis and peritoneal dialysis (PD) in clinical studies. However, folate transport has never been mentioned as a factor contributing to low plasma folate levels in patients undergoing PD. The peritoneal equilibrium test (PET) assesses the plasma creatinine level and glucose transport abilities. This study aimed to evaluate the association between plasma folate levels and folate transport during PD based on PET grades.

METHODS

This study recruited 50 patients who underwent PD for ≥3 months and were categorized according to PET grades. Data regarding plasma folate levels and dialysate folate were collected. The primary outcomes were the relationship between the PET grade and plasma folate level and between the PET grade and dialysate-to-plasma folate concentration ratio (D/P folate). Furthermore, the difference in the plasma folate level and D/P folate between men and women was assessed.

RESULTS

The plasma folate level and the D/P folate significantly differed among the 4 PET groups (both P < .001). PET grade was significantly negatively correlated with plasma folate levels (r = -0.56, P < .001) and positively correlated with D/P folate (r = 0.686, P < .001). In subgroup analysis, neither the plasma folate level nor the D/P folate significantly differed between men and women.

CONCLUSIONS

Our study provides clinical evidence that the PET grade is associated with the plasma folate level and D/P folate, regardless of sex. Larger cohort studies are warranted to assess the importance of folate supplementation during PD based on PET grades.

Serum Vitamin B12 Deficiency in Chronic Hemodialysis Patients

Introduction Essential vitamins like folate and vitamin B12 are crucial for many physiological functions. Patients with renal failure undergoing regular hemodialysis in the general population may experience harmful effects from vitamin B12 deficits. Therefore, this study aimed to determine the frequency of vitamin B12 deficiency in hemodialysis patients and its association with other clinical parameters. Methods This cross-sectional study was conducted at the dialysis unit of Patel Hospital and Lifeline Hospital, Karachi, using a non-probability consecutive sampling technique after obtaining ethical approval from Lifeline Hospital (LLH/HR/02-22). The study duration was six months, from January 10, 2023, to July 22, 2023. A total of 135 adult renal failure patients with ages >18 and <70 years on maintenance hemodialysis for >1 year were included in the study. The chi-square test was used to determine the association between vitamin B12 deficiency and age and gender. A p-value of 0.05 was considered statistically significant. Results The study findings showed that out of 135 patients, 82 (60.7%) were males and 53 (39.3%) were females, with a mean age of 50.80 ± 10.03 years. The duration of hemodialysis was approximately 1-2 years in 98 (72.6%) patients, 2-3 years in 27 (20.0%) patients, and 3-4 years in only 9 (6.7%) patients. The mean serum vitamin B-12 levels were 411.61 ± 224.95 pg/ml, with 30 (22.2%) of the subjects being deficient. In terms of duration of hemodialysis, there was a significant association (p= 0.013). Between patients with normal 4 (4%) and deficient 5 (17%) vitamin B12 and 3-4 years of hemodialysis. Conclusion In this study, we found that a significant proportion of patients on chronic hemodialysis had vitamin B12 deficiency. Moreover, vitamin B12 deficiency was significantly associated with duration of hemodialysis. Therefore, we recommend periodic vitamin B12 testing in hemodialysis patients to avoid any associated complications.

The origin of vitamin B12 levels and risk of all-cause, cardiovascular and cancer specific mortality: A systematic review and dose-response meta-analysis

BACKGROUND

Vitamin B12 is essential to human but the implications of serum vitamin B12 level for mortality in clinical practice remain unclear. We conducted a systematic review and dose-response meta-analysis to quantify the relationship between vitamin B12 levels and the risk of all-cause, cardiovascular, and cancer mortality.

METHODS

Electronic databases of PubMed, Embase, and the Cochrane Library Central Register of Controlled Trials were searched from inception through May 2023. Two reviewers independently extracted individual study data and evaluated the risk of bias among the studies using the Newcastle‒Ottawa Scale. To examine a potential nonlinear relationship between the vitamin B12 levels and all-cause mortality, we performed a two-stage random effects dose‒response meta-analysis.

RESULTS

Twenty-two cohort studies (92,346 individuals with 10,704 all-cause deaths) were included. A linear trend dose-response analysis showed that each 100 pmol/L increase in serum vitamin B12 concentration was associated with a 4 % higher risk of all-cause mortality in the general population (adjusted HR 1.04, 95 % confidence interval CI 1.01 to 1.08; n = 8; P non-linearity = 0.11) and a 6 % higher risk for all-cause mortality in older adults (adjusted HR 1.06, 95 % CI 1.01 to 1.13; n = 4; P non-linearity = 0.78). Current evidence was mixed for the association between serum vitamin B12 concentration and cardiovascular mortality and was limited for cancer mortality. The meta-analysis of cohort studies showed a positive association between a high serum vitamin B12 concentration (>600 pmol/L) and all-cause mortality (adjusted HR 1.50, 95 % CI 1.29 to 1.74; n = 10; p < 0.01), CVD mortality (adjusted HR 2.04, 95 % CI 0.99 to 4.19; n = 2; p = 0.02), except cancer mortality (adjusted HR 1.56, 95 % CI 0.82 to 2.95; n = 3). Similarly, serum vitamin B12 concentrations (400-600 pmol/L) were associated with increased all-cause mortality (adjusted HR 1.34, 95 % CI 1.10 to 1.64; n = 9; p < 0.01).

CONCLUSIONS

Serum vitamin B12 concentration was positively associated with the risk of all-cause mortality, especially among older adults, with a linear increasing trend. These findings suggested the primary cause of elevated level of serum vitamin B12 concentration should be timely identified and effectively managed in clinical practice.

Vitamin Needs and Treatment for Chronic Kidney Disease Patients

This paper summarizes the biochemistry, metabolism, and dietary needs of vitamins in patients with chronic kidney disease (CKD) and kidney transplant recipients. Evidence indicates that the dietary intake, in vivo synthesis, urinary excretion or metabolism of different vitamins may be substantially altered in kidney failure. There are discrepancies in vitamin status assessment depending on whether the assay is functional or measuring the blood vitamin level. Whether vitamin supplements should be routinely prescribed for patients with CKD is controversial. Because low dietary intake and compounds that interfere with vitamin activity are not uncommon in patients with CKD, and water-soluble vitamin supplements appear safe and not costly, the authors recommend that supplements of the water-soluble vitamins should be routinely offered to these individuals. More research is needed to assess vitamin nutrition and function and to determine the daily vitamin needs for all patients with CKD.

Association of Serum Vitamin B12 and Circulating Methylmalonic Acid Levels with All-Cause and Cardiovascular Disease Mortality among Individuals with Chronic Kidney Disease

(1) Background: it is unclear whether serum vitamin B₁₂ and circulating methylmalonic acid (MMA) are related with a poor prognosis among individuals with chronic kidney disease (CKD); (2) Methods: this prospective cohort study included 2589 individuals with CKD who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2004, and from 2011 to 2014, respectively. Hazard ratios (HRs) and 95% Cis for the associations of MMA and vitamin B₁₂ levels with the risk of all-cause and cardiovascular disease (CVD) mortality were calculated using multivariable Cox proportional hazards regression models. Restricted cubic spline analyses were used to examine the non-linear association of MMA levels with all-cause and CVD mortality. (3) Results: among the 2589 participants, we identified 1192 all-cause deaths and 446 CVD deaths, respectively, with a median follow-up of 7.7 years. Compared with participants with MMA < 123 nmol/L, those with MMA ≥ 240 nmol/L had an increased all-cause and CVD mortality in the multivariable-adjusted model [HR (95% CI), 2.01 (1.54-2.62) and 1.76 (1.18-2.63), respectively]; (4) Conclusions: higher circulating MMA levels were found to be strongly associated with an elevated all-cause and CVD mortality among individuals with CKD, while serum vitamin B₁₂ levels were not associated.

Etiology of Anemia and Risk Factors of Mortality among Hospitalized Patients: A Real-Life Retrospective Study in a Tertiary Center in Greece

Anemia is a prominent global health issue with a wide variety of causes and can be associated with decreased quality of life, increased hospitalization, and higher mortality, especially in older individuals. Therefore, studies further shedding light on the causes and the risk factors of this condition should be performed. The aim of the present study was to examine the causes of anemia in hospitalized patients in a tertiary hospital in Greece and identify risk factors related to higher mortality. In total, 846 adult patients with a diagnosis of anemia were admitted during the study period. The median age was 81 years, and 44.8% were male. The majority of patients had microcytic anemia, with the median mean corpuscular volume (MCV) being 76.3 fL and the median hemoglobin being 7.1 g/dL. Antiplatelets were used by 28.6% of patients, while 28.4% were using anticoagulants at the time of diagnosis. At least one unit of packed red blood cells (PRBCs) was transfused in 84.6% of patients, and a median of two PRBCs was used per patient. A gastroscopy was performed in 55%, and a colonoscopy was performed in 39.8% of patients in the present cohort. Anemia was considered to be multifactorial in almost half the cases, while the most commonly identified cause was iron deficiency anemia, more commonly with positive endoscopic findings. Mortality was relatively low, at 4.1%. Multivariate logistic regression analysis identified higher B12 levels and longer duration of hospital stay to be independently positively associated with mortality.

Non-linear associations of serum and red blood cell folate with risk of cardiovascular and all-cause mortality in hypertensive adults

This study aims to assess the associations of serum and red blood cell (RBC) folate with cardiovascular and all-cause mortality in hypertensive adults. Data on serum and RBC folate from the 1999-2014 National Health and Nutrition Examination Survey were included. Through December 31, 2015, cardiovascular and all-cause mortality were identified from the National Death Index. Multiple Cox regression and restricted cubic spline analyses were used to determine the relationship between folate concentrations and outcomes. A total of 13,986 hypertensive adults were included in the analysis (mean age, 58.5 ± 16.1 years; 6898 [49.3%] men). At a median of 7.0 years of follow-up, 548 cardiovascular deaths and 2726 all-cause deaths were identified. After multivariable adjustment, the fourth quartile of serum folate was associated with cardiovascular (HR = 1.32 [1.02-1.70]) and all-cause (HR = 1.20 [1.07-1.35]) mortality compared to the second quartile, whereas the first quartile was only linked with increased all-cause (HR = 1.29 [1.15-1.46]) mortality. The inflection points for the non-linear associations of serum folate with cardiovascular and all-cause mortality were 12.3 ng/mL and 20.5 ng/mL, respectively. In addition, the highest quartile of RBC folate was associated with cardiovascular (HR = 1.68 [1.30-2.16]) and all-cause (HR = 1.30 [1.16-1.46]) mortality compared to the second quartile, but the lowest quartile was not associated with either outcome. The inflection points for the non-linear associations of RBC folate with cardiovascular and all-cause mortality were 819.7 and 760.1 ng/mL, respectively. The findings suggest non-linear associations between serum and RBC folate levels and the risk of cardiovascular and all-cause mortality in hypertensive adults.

Prognostic value of red cell distribution width and mean corpuscular volume on mortality in hemodialysis patients

BACKGROUND

Anemia is a common consequence of chronic kidney disease (CKD). Red cell distribution width (RDW) and mean corpuscular volume (MCV) are principally used for differential diagnosis of anemia. Limited evidence is available for its prognostic value for mortality in hemodialysis (HD) patients. We aimed to definite the relationship between RDW and MCV and mortality in HD patients.

METHOD

This cohort study examined all-cause and cardiovascular (CV) mortality with 181 maintenance HD patients from February 2015. Patients were divided into four groups according to the median of RDW and MCV. Pearson analysis was conducted to determine the related factors of RDW and MCV. The independent association of RDW and MCV with mortality was examined with Kaplan-Meier curve and Cox regression analysis.

RESULTS

This study included 181 HD patients for a median follow-up of 71 months. We found RDW was positively related to neutrophil count, C-reaction protein, and ferritin, while negatively related to hemoglobin, albumin, and creatinine. Only neutrophil count and ferritin were significantly related to MCV in this study. In the multivariate Cox regression analysis, the high RDW group was associated with higher risk of all-cause mortality (odds ratio, 3.787; 95% confidence interval, 1.037 to 13.834; p = 0.044). The relationship between RDW and MCV and CV mortality was not significant.

CONCLUSIONS

RDW could emerge as an additive risk factor for all-cause mortality in maintenance HD patients, independent of other factors. An absolute value of MCV to predict mortality and the underlying pathophysiologic mechanisms should be confirmed in the future.

Supplementation with Folic Acid and Cardiovascular Outcomes in End-Stage Kidney Disease: A Multi-Institution Cohort Study

BACKGROUND

Folate is a water-soluble vitamin and is essential for maintaining cell functions. Dialysis removes folate, and folate deficiency is reported in patients with end-stage kidney disease (ESKD). However, there is no consensus as to the appropriate dosage of folate supplements and their advantages and disadvantages for patients with ESKD.

METHODS

This study was based on the electronic medical records of the Chang Gung Research Database (CGRD) of the Chang Gung Medical Foundation. We included patients who were diagnosed with ESKD, initiated hemodialysis, and were given folic acid supplements at any point from 1 January 2001 to 31 December 2019. The patients were divided into weekly and daily folic acid supplementation groups. We reduced the effects of confounding through the inverse probability of treatment weighting based on the propensity score.

RESULTS

We identified 2081 and 954 newly diagnosed patients with ESKD, who received daily and weekly folic acid supplements. The mean follow-up time was 5.8 years, and the event rates of arteriovenous access thrombosis were 17.0% and 23.6% in the daily and weekly folic acid supplementation groups (sub-distribution hazard ratio = 0.69, 95% confidence interval = 0.61 to 0.77), respectively. Neither group significantly differed in the occurrence of other clinical events, such as major cardiovascular cardiac events (e.g., myocardial infarction and ischemic stroke), all-cause mortality, cardiovascular death, infection death, malignancy, and adverse effects.

CONCLUSION

a daily 5 mg folic acid supplementation might result in a lower event rate of arteriovenous access thrombosis in patients with ESKD than weekly folic acid supplementation. Further prospective studies are warranted to explore the preventive effect of folate on thrombosis.

The Impact of Chronic Kidney Disease on Nutritional Status and Its Possible Relation with Oral Diseases

Several studies have demonstrated a strong relation between periodontal diseases and chronic kidney disease (CKD). The main mechanisms at the base of this link are malnutrition, vitamin dysregulation, especially of B-group vitamins and of C and D vitamins, oxidative stress, metabolic acidosis and low-grade inflammation. In particular, in hemodialysis (HD) adult patients, an impairment of nutritional status has been observed, induced not only by the HD procedures themselves, but also due to numerous CKD-related comorbidities. The alteration of nutritional assessment induces systemic manifestations that have repercussions on oral health, like oral microbiota dysbiosis, slow healing of wounds related to hypovitaminosis C, and an alteration of the supporting bone structures of the oral cavity related to metabolic acidosis and vitamin D deficiency. Low-grade inflammation has been observed to characterize periodontal diseases locally and, in a systemic manner, CKD contributes to the amplification of the pathological process, bidirectionally. Therefore, CKD and oral disease patients should be managed by a multidisciplinary professional team that can evaluate the possible co-presence of these two pathological conditions, that negatively influence each other, and set up therapeutic strategies to treat them. Once these patients have been identified, they should be included in a follow-up program, characterized by periodic checks in order to manage these pathological conditions.

Vitamin B12 and chronic kidney disease

Chronic Kidney Disease (CKD) is an emerging public health issue with a fast-growing global prevalence. Impairment in vitamin B12 metabolism is considered a nontraditional risk factor of poor outcomes associated with CKD, and there is greater interest from the scientific community than ever before to explore the role and influence of vitamin B12 in CKD. Homocysteine metabolism forms an important component of the vitamin B12 metabolic pathway. Hyperhomocysteinemia is frequently observed in CKD and End-Stage Kidney Disease (ESKD), but its representation as a prognostic marker for CKD outcomes is still not fully clear. This chapter reviews the vitamin B12 and homocysteine metabolic pathways and their dysfunction in CKD states. Biochemical factors and the MTHFR genetic polymorphisms which disrupt vitamin B12 and homocysteine metabolism are explored. The mechanisms of homocysteine-mediated and vitamin B12-mediated tissue damage in CKD are discussed. This chapter reviews current perspective on definition and measurement of plasma vitamin B12 levels in the CKD population. Updated evidence investigating the prognostic role of vitamin B12 for CKD outcomes is presented. Findings from major clinical trials conducted relating to outcomes from multivitamin (including folic acid and vitamin B12) supplementation in nondialysis and dialysis-dependent CKD are highlighted. The prognostic value of vitamin B12 and effects of vitamin B12 supplementation in the context of kidney transplantation and acute kidney injury is also reviewed. Future research considerations are summarized based on evidence gaps in our knowledge base of this topic. Greater abundance of high-level evidence to guide an approach toward vitamin B12 measurement, monitoring and supplementation in CKD may contribute to improved clinical outcomes.

Cobalamin Intake and Related Biomarkers: Examining Associations With Mortality Risk Among Adults With Type 2 Diabetes in NHANES

OBJECTIVE

Despite that periodical monitoring of cobalamin (vitamin B12) in metformin-treated patients with diabetes is recommended, cobalamin-associated mortality benefits or risks remain unclear. We investigated the association between cobalamin intake and related biomarkers and mortality risk in adults with diabetes using metformin or not.

RESEARCH DESIGN AND METHODS

This study included 3,277 adults with type 2 diabetes from the National Health and Nutrition Examination Survey (NHANES) and followed up until 31 December 2015. Weighted Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs for mortality risk.

RESULTS

Among 3,277 participants, 865 all-cause deaths occurred during a median follow-up of 7.02 years. There was no robust relationship between all-cause mortality and serum cobalamin or intake of foods or cobalamin supplements, regardless of metformin treatment (each P ≥ 0.120). The doubling of methylmalonic acid (MMA), a cobalamin-deficiency marker, was significantly associated with higher all-cause (HR 1.31 [95% CI 1.18-1.45], P < 0.001) and cardiac (HR 1.38 [95% CI 1.14-1.67], P = 0.001) mortality. Cobalamin sensitivity was assessed by the combination of binary B12low/high and MMAlow/high (cutoff values: cobalamin 400 pg/mL, MMA 250 nmol/L). Patients with decreased cobalamin sensitivity (MMAhighB12high) had the highest mortality risk. The multivariable-adjusted HRs (95% CIs) of all-cause mortality in MMAlowB12low, MMAlowB12high, MMAhighB12low, and MMAhighB12high groups were 1.00 (reference), 0.98 (0.75-1.28), 1.49 (1.16-1.92), and 1.96 (1.38-2.78), respectively. That association was especially significant in metformin nonusers.

CONCLUSIONS

Serum and dietary cobalamin were not associated with reduced mortality. Decreased cobalamin sensitivity was significantly associated with all-cause and cardiac mortality, particularly among metformin nonusers.

Gut Microbiome, Functional Food, Atherosclerosis, and Vascular Calcifications-Is There a Missing Link?

The gut microbiome is represented by the genome of all microorganisms (symbiotic, potential pathogens, or pathogens) residing in the intestine. These ecological communities are involved in almost all metabolic diseases and cardiovascular diseases are not excluded. Atherosclerosis, with a continuously increasing incidence in recent years, is the leading cause of coronary heart disease and stroke by plaque rupture and intraplaque hemorrhage. Vascular calcification, a process very much alike with osteogenesis, is considered to be a marker of advanced atherosclerosis. New evidence, suggesting the role of dietary intake influence on the diversity of the gut microbiome in the development of vascular calcifications, is highly debated. Gut microbiota can metabolize choline, phosphatidylcholine, and L-carnitine and produce vasculotoxic metabolites, such as trimethylamine-N-oxide (TMAO), a proatherogenic metabolite. This review article aims to discuss the latest research about how probiotics and the correction of diet is impacting the gut microbiota and its metabolites in the atherosclerotic process and vascular calcification. Further studies could create the premises for interventions in the microbiome as future primary tools in the prevention of atherosclerotic plaque and vascular calcifications.

Homocysteine-Lowering Interventions in Chronic Kidney Disease

The incidence of cardiovascular events and mortality is higher in patients with chronic kidney disease (CKD) compared to the general population. Homocysteine (Hcy) appears to be an independent risk factor for cardiovascular diseases in general populations and patients with CKD. Further, hyperhomocysteinemia can cause endothelial damage and increase the activity and production of coagulation factors, and its prevalence among patients with end-stage renal disease is approximately 85%-100%. Most treatments, which lower Hcy levels and have been considered in previous studies, include folic acid, B vitamins, omega-3 fatty acids, and N-acetylcysteine. However, the effect of therapies that can decrease Hcy levels and thus cardiovascular events in these patients is still unclear. The results are conflicting and require further investigation. To guide treatment decisions and improve patient outcomes, multiple databases were searched, including Web of Science, PubMed, and Medline to summarize the available evidence (i.e., clinical trial and meta-analyses) on Hcy-lowering interventions and cardiovascular events.

Serum Folate and All-Cause Mortality is of Non-Linear Relationship Among Population with Chronic Kidney Disease: A Retrospective Cohort Study

AIM

A transition toward high serum folate concentrations has been noticed following the mandatory folate fortification. To explore this further, we studied the relationship between folate and health outcomes in population with chronic kidney disease (CKD).

METHODS

We retrospectively explored the relationships between serum folate and risk of all-cause death in this population. We analyzed data of 2142 subjects with CKD who participated in the National Health and Nutrition Examination Survey (NHANES) 1999-2006. Vital status was followed through December 31, 2006.

RESULTS

Cox regression was used to estimate hazard ratios (HRs) of mortality for individuals with serum folate in rest quintiles compared with individuals with the fourth quintile. After an average follow-up of 57.4 months with 157 deaths recorded, a reversed J-shaped association was revealed after conducting multivariable adjustment. The mortality rate in population with lower and higher folate levels were 8.29% and 12.67%, respectively, and the corresponding adjusted HRs were 2.41 (95% confidence interval, CI=1.32-4.40) and 2.10 (1.20-3.70). Kaplan-Meier curve showed survival benefits for the fourth quintile of serum folate as compared to the first and fifth quintile.

CONCLUSION

Serum folate concentrations may influence all-cause mortality in a non-linear pattern in the CKD population. It is reasonable to recommend periodic surveillance in the CKD population to maintain the serum folate concentration in an appropriate level.

Update on Safety Profiles of Vitamins B1, B6, and B12: A Narrative Review

The neurotropic B vitamins B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) are essential for proper functioning of the nervous system. Deficiencies may induce neurological disorders like peripheral neuropathy (PN) and mainly occur in vulnerable populations (eg, elderly, diabetics, alcoholics). As epidemiologic cohort studies raised safety concerns about vitamin B6/B12 intake being potentially associated with increased risks of hip fracture (HF) and lung cancer (LC), we explored these aspects and performed comprehensive literature searches. However, we suggest not to neglect actual high-risk factors (eg, smoking in LC, higher age in HF) by focusing on individual nutrients, but to examine the complex interaction of numerous factors involved in disease development. Because it warrants continued consideration, we also provide an update on neurotoxicity associated with vitamin B6. We consider that neurological side effects due to vitamin B6 intake are rare and only occur with high daily doses and/or longer treatment duration. The benefit-risk ratio of high-dose treatment with neurotropic B vitamins in indications like PN is therefore considered advantageous, particularly if dosing recommendations are followed and serum levels monitored.

Relationship between serum B12 concentrations and mortality: experience in NHANES

BACKGROUND

There is conflicting evidence in the literature on the association between (elevated) serum B12 concentrations and subsequent disease or mortality. We evaluated in the NHANES general population the association of serum B12 concentrations as well as vitamin B12 supplement intake with all-cause, cardiovascular, and cancer-related mortality, while taking into account demographic and lifestyle factors and significant other diseases which are known to be associated with poorer outcome.

METHODS

The main outcomes of our study were all-cause mortality, cardiovascular mortality, and cancer-related mortality. Mortality status and cause of death were determined by NHANES-linked National Death Index public access files through December 31, 2015. The association of serum B12 concentrations and vitamin B12 supplement intake with mortality was assessed with Cox proportional hazard (PH) models, with adjustment for a number of relevant demographic and lifestyle factors and comorbidity.

RESULTS

The final study population of 24,262 participants had a mean age of 48 (SD 19) years; 50.1% were males. The median follow-up duration was 109 months (range 1-201 months). On the census day of December 31, 2015, 3023 participants were determined as deceased (12.5%). The fully adjusted Cox PH model indicated that low serum B12 concentrations < 140 pmol/l were associated with a small increase in all-cause (hazard ratio, HR 1.39, 95% CI 1.08-1.78, p = 0.011) and cardiovascular (HR 1.64, 95% CI 1.08-2.47, p = 0.020) mortality. Similarly, high serum B12 concentrations > 700 pmol/l were associated with an increase in cardiovascular mortality only (HR 1.45, 95% CI 1.01-2.06, p = 0.042). Participants with a diagnosis of hypertension, dyslipidemia, CVD, and cancer more frequently used vitamin B12-containing supplements than those without these diagnoses. We could not demonstrate an association between vitamin B12 supplement intake and mortality, when adjusted for comorbidity.

CONCLUSIONS

In the general population of NHANES, low serum B12 concentrations were associated with a moderate increase in all-cause mortality. There was a small but significant increase in cardiovascular mortality in the groups with low or high serum B12. High intake of vitamin B12 in the form of supplements was not associated with any adverse effect on mortality and therefore can be regarded as safe.

Novel genes associated with folic acid-mediated metabolism in mouse: A bioinformatics study

Folic acid plays an essential role in the central nervous system and cancer. This study aimed to screen genes related to folic acid metabolism. Datasets (GSE80587, GSE65267 and GSE116299) correlated to folic acid were screened in the Gene Expression Omnibus. Weighed gene co-expression network analysis was performed to identify modules associated with sample traits of folic acid and organs (brain, prostate and kidney). Functional enrichment analysis was performed for the eigengenes in modules that were significantly correlated with sample traits. Accordingly, the hub genes and key nodes in the modules were identified using the protein interaction network. A total of 17,252 genes in three datasets were identified. One module, which included 97 genes that were highly correlated with sample traits (including folic acid treatment [cor = -0.57, P = 3e-04] and kidney [cor = -0.68, p = 4e-06]), was screened out. Hub genes, including tetratricopeptide repeat protein 38 (Ttc38) and miR-185, as well as those (including Sema3A, Insl3, Dll1, Msh4 and Snai1) associated with "neuropilin binding", "regulation of reproductive process" and "vitamin D metabolic process", were identified. Genes, including Ttc38, Sema3A, Insl3, Dll1, Msh4 and Snai1, were the novel factors that may be associated with the development of the kidneys and related to folic acid treatment.

Plant-Dominant Low-Protein Diet for Conservative Management of Chronic Kidney Disease

Chronic kidney disease (CKD) affects >10% of the adult population. Each year, approximately 120,000 Americans develop end-stage kidney disease and initiate dialysis, which is costly and associated with functional impairments, worse health-related quality of life, and high early-mortality rates, exceeding 20% in the first year. Recent declarations by the World Kidney Day and the U.S. Government Executive Order seek to implement strategies that reduce the burden of kidney failure by slowing CKD progression and controlling uremia without dialysis. Pragmatic dietary interventions may have a role in improving CKD outcomes and preventing or delaying dialysis initiation. Evidence suggests that a patient-centered plant-dominant low-protein diet (PLADO) of 0.6–0.8 g/kg/day composed of >50% plant-based sources, administered by dietitians trained in non-dialysis CKD care, is promising and consistent with the precision nutrition. The scientific premise of the PLADO stems from the observations that high protein diets with high meat intake not only result in higher cardiovascular disease risk but also higher CKD incidence and faster CKD progression due to increased intraglomerular pressure and glomerular hyperfiltration. Meat intake increases production of nitrogenous end-products, worsens uremia, and may increase the risk of constipation with resulting hyperkalemia from the typical low fiber intake. A plant-dominant, fiber-rich, low-protein diet may lead to favorable alterations in the gut microbiome, which can modulate uremic toxin generation and slow CKD progression, along with reducing cardiovascular risk. PLADO is a heart-healthy, safe, flexible, and feasible diet that could be the centerpiece of a conservative and preservative CKD-management strategy that challenges the prevailing dialysis-centered paradigm.

Vitamin B Supplementation and Nutritional Intake of Methyl Donors in Patients with Chronic Kidney Disease: A Critical Review of the Impact on Epigenetic Machinery

Cardiovascular morbidity and mortality are several-fold higher in patients with advanced chronic kidney disease (CKD) and end-stage renal disease (ESRD) than in the general population. Hyperhomocysteinemia has undoubtedly a central role in such a prominent cardiovascular burden. The levels of homocysteine are regulated by methyl donors (folate, methionine, choline, betaine), and cofactors (vitamin B6, vitamin B12,). Uremia-induced hyperhomocysteinemia has as its main targets DNA methyltransferases, and this leads to an altered epigenetic control of genes regulated through methylation. In renal patients, the epigenetic landscape is strictly correlated with the uremic phenotype and dependent on dietary intake of micronutrients, inflammation, gut microbiome, inflammatory status, oxidative stress, and lifestyle habits. All these factors are key contributors in methylome maintenance and in the modulation of gene transcription through DNA hypo- or hypermethylation in CKD. This is an overview of the epigenetic changes related to DNA methylation in patients with advanced CKD and ESRD. We explored the currently available data on the molecular dysregulations resulting from altered gene expression in uremia. Special attention was paid to the efficacy of B-vitamins supplementation and dietary intake of methyl donors on homocysteine lowering and cardiovascular protection.

Folate-appended cyclodextrin carrier targets ovarian cancer cells expressing the proton-coupled folate transporter

Folate receptor alpha (FRα) is overexpressed in >80% of epithelial ovarian cancer (EOC). Accordingly, folate is attracting attention as a targeting ligand for EOC. For EOC patients, paclitaxel (PTX) is generally used as a first‐line chemotherapeutic agent in combination with platinum‐based drugs. Cyclodextrin (CyD) is a potential new formulation vehicle for PTX that could replace Cremophor‐EL, a traditional formulation vehicle that causes significant side effects, including neutropenia. Several years ago, folate‐appended β‐CyD (Fol‐c₁‐β‐CyD) was developed as an FRα‐targeting drug carrier, but its efficacy as a treatment for EOC remains to be determined. In this study, we assessed the antitumor activity of PTX in Fol‐c₁‐β‐CyD (PTX/Fol‐c₁‐β‐CyD) in EOC‐derived cell lines. We found that PTX/Fol‐c₁‐β‐CyD killed not only FRα‐expressing cells but also FRα‐negative cells. In the FRα‐negative A2780 cells, knockdown of proton‐coupled folate transporter (PCFT) significantly decreased the cytotoxicity of PTX/Fol‐c₁‐β‐CyD, whereas knockdown of FRα did not. By contrast, knockdown of either FRα or proton‐coupled folate transporter (PCFT) decreased the cytotoxicity of PTX/Fol‐c₁‐β‐CyD in FRα‐expressing SK‐OV‐3 cells. Furthermore, the cytotoxicity of PTX/Fol‐c₁‐β‐CyD in A2780 cells was increased at acidic pH, and this increase was suppressed by PCFT inhibitor. In mice intraperitoneally inoculated with FRα‐expressing or PCFT‐expressing EOC cells, intraperitoneal administration of PTX/Fol‐c₁‐β‐CyD significantly suppressed the growth of both types of EOC cells relative to PTX alone, without inducing a significant change in the neutrophil/white blood cell ratio. Our data suggest that Fol‐c₁‐β‐CyD targets not only FRα but also PCFT, and can efficiently deliver anticancer drugs to EOC cells in the peritoneal cavity.

Association of Plasma Concentration of Vitamin B12 With All-Cause Mortality in the General Population in the Netherlands

IMPORTANCE

Higher plasma concentrations of vitamin B12 have been associated with mortality in elderly and hospitalized populations, including patients with chronic kidney disease, but the association of plasma concentrations of vitamin B12 with mortality in the general population remains unclear.

OBJECTIVE

To investigate the association of plasma concentrations of vitamin B12 with all-cause mortality.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal cohort study used post hoc analysis to examine data from participants of the Prevention of Renal and Vascular End-stage Disease Study in Groningen, the Netherlands. Participants included individuals who completed the second screening visit beginning January 1, 2001, excluding those who were missing values of vitamin B12 plasma concentrations or used vitamin B12 supplementation. Follow-up time was defined between the beginning of the second screening round to end of follow-up on January 1, 2011. Data analysis was conducted from October 2, 2018, to February 22, 2019.

EXPOSURES

Plasma vitamin B12 concentration level.

MAIN OUTCOMES AND MEASURES

Death as recorded by the Central Bureau of Statistics of Groningen, the Netherlands.

RESULTS

A total of 5571 participants (mean [SD] age, 53.5 [12.0] years; 2830 [50.8%] men) were included in analyses. Median (interquartile range) plasma concentration of vitamin B12 was 394.42 (310.38-497.42) pg/mL. During the median (interquartile range) of 8.2 (7.7-8.9) years of follow-up, 226 participants (4.1%) died. According to quartiles of the distribution of plasma vitamin B12 concentration levels, mortality rates were 33.8 deaths per 10 000 person-years for the quartile with the lowest plasma concentration of vitamin B12 and 65.7 deaths per 10 000 person-years for the quartile with the highest plasma concentration of vitamin B12. After adjustment for multiple clinical and laboratory variables, Cox regression analyses found a significant association between higher vitamin B12 plasma concentration level and increased risk of all-cause mortality (hazard ratio per 1-SD increase, 1.25 [95% CI, 1.06-1.47]; P = .006).

CONCLUSIONS AND RELEVANCE

These findings suggest that higher levels of plasma concentrations of vitamin B12 were associated with increased risk of all-cause mortality after adjusting for age, sex, renal function, and other clinical and laboratory variables. The mechanisms underlying this association remain to be established.

Methyl Donor Nutrients in Chronic Kidney Disease: Impact on the Epigenetic Landscape

Epigenetic alterations, such as those linked to DNA methylation, may potentially provide molecular explanations for complications associated with altered gene expression in illnesses, such as chronic kidney disease (CKD). Although both DNA hypo- and hypermethylation have been observed in the uremic milieu, this remains only a single aspect of the epigenetic landscape and, thus, of any biochemical dysregulation associated with CKD. Nevertheless, the role of uremia-promoting alterations on the epigenetic landscape regulating gene expression is still a novel and scarcely studied field. Although few studies have actually reported alterations of DNA methylation via methyl donor nutrient intake, emerging evidence indicates that nutritional modification of the microbiome can affect one-carbon metabolism and the capacity to methylate the genome in CKD. In this review, we discuss the nutritional modifications that may affect one-carbon metabolism and the possible impact of methyl donor nutrients on the microbiome, CKD, and its phenotype.

Folic Acid and Vitamin B12 Administration in CKD, Why Not?

Patients affected by chronic kidney disease (CKD) or end-stage renal disease (ESRD) experience a huge cardiovascular risk and cardiovascular events represent the leading causes of death. Since traditional risk factors cannot fully explain such increased cardiovascular risk, interest in non-traditional risk factors, such as hyperhomocysteinemia and folic acid and vitamin B12 metabolism impairment, is growing. Although elevated homocysteine blood levels are often seen in patients with CKD and ESRD, whether hyperhomocysteinemia represents a reliable cardiovascular and mortality risk marker or a therapeutic target in this population is still unclear. In addition, folic acid and vitamin B12 could not only be mere cofactors in the homocysteine metabolism; they may have a direct action in determining tissue damage and cardiovascular risk. The purpose of this review was to highlight homocysteine, folic acid and vitamin B12 metabolism impairment in CKD and ESRD and to summarize available evidences on hyperhomocysteinemia, folic acid and vitamin B12 as cardiovascular risk markers, therapeutic target and risk factors for CKD progression.

Mean Corpuscular Volume and Mortality in Incident Hemodialysis Patients

BACKGROUND/AIMS

Anemia is common in patients with advanced chronic kidney disease (CKD). A proportion of patients present with macrocytic anemia, manifested by elevated mean corpuscular volume (MCV), which has been associated with worse outcomes in CKD patients. However, it is unknown whether elevated MCV is associated with higher mortality risk in incident hemodialysis (HD) patients.

METHODS

This retrospective observational cohort study examined all-cause, cardiovascular, and infectious mortality associations with both baseline and time-varying MCV in 109,501 incident HD patients using Cox proportional hazards models with 3 levels of hierarchical multivariable adjustment. Odds ratios of high versus low baseline MCV were evaluated using logistic regression.

RESULTS

The mean age of patients was 65 ± 15 (standard deviation) years and the cohort was 44% female, 58% diabetic, and 31% African American. Higher MCV was associated with older age, female sex, non-Hispanic White race-ethnicity, alcohol consumption, and having a decreased albumin or protein intake. Patients with higher MCV levels (> 98 fL) had a higher all-cause, cardiovascular, and infectious mortality risk in both baseline and time varying models, and across all levels of adjustment. In the fully adjusted models, compared to a reference of MCV 92-< 94 fL, patients with a baseline MCV > 100+ fL had a 28% higher risk of all-cause mortality (hazard ratio [HR] 1.28, 95% CI 1.22-1.34), 27% higher risk of cardiovascular mortality (HR 1.27, 95% CI 1.18-1.36), and 18% higher risk of infectious mortality (HR 1.18, 95% CI 1.02-1.38). Associations of higher MCV with these adverse outcomes persisted across all examined subgroups of clinical characteristics.

CONCLUSIONS

Higher MCV was associated with higher all-cause, cardiovascular, and infectious mortality in HD patients. Further investigation is necessary to understand the underlying nature of the observed association.

Forecast post-dialysis blood pressure in hemodialysis patients with intradialytic hypertension

Background: Intradialytic hypertension (IDH) is emerging as an important issue in maintenance hemodialysis (MHD) patients. This study aimed to discuss potential factors related to IDH and build forecasting models for post-dialysis blood pressure (BP) in MHD patients with IDH. Methods: A total of 266 MHD patients were enrolled, included 133 (50%) patients with IDH and 133 patients without IDH. The BP and pulse were determined and recorded over six consecutive dialysis treatments. Forecasting models were established by simple and multiple linear regressions. The Pearson correlation coefficient was used to estimate the association between the values of SBP at pre-HD, intra-HD and post-HD. Results: Lower levels of hemoglobin, albumin, folic acid and magnesium, higher levels of high sensitivity C-reactive protein, ferritin, and erythropoiesis-stimulating agents resistance index (ERI) were detected in the IDH patients. The IDH patients also had lower dry weight, ejection fraction of left ventricular (LVEF), higher interdialytic weight gain (IDWG, % post-HD body weight), and ventricular cardiothoracic ratio (CTR) than non-IDH patients. A linear relationship was revealed between intradialytic SBP in IDH patients, indicating that the pre-HD and intra-HD SBP were correlated with post-HD SBP. Furthermore, simple and multiple linear regression models were built to forecast the values of post-HD SBP in IDH patients. Conclusions: The chronic inflammation, poor IDWG control, LV diastolic dysfunction, as well as low serum folic acid and magnesium might be associated with increasing prevalence of IDH in MHD patients. Forecasting models for post-HD SBP could help to control hypertension during HD treatments.

Elevated Plasma Vitamin B12 Concentrations Are Independent Predictors of In-Hospital Mortality in Adult Patients at Nutritional Risk

Background: Elevated plasma vitamin B12 concentrations were identified as predictors of mortality in patients with oncologic, hepatic and renal diseases, and in elderly and critically ill medical patients. The association between vitamin B12 concentrations and in-hospital mortality in adult patients at nutritional risk has not been assessed. Methods: In this five-year prospective study, we investigated whether high vitamin B12 concentrations (>1000 pg/mL) are associated with in-hospital mortality in 1373 not-bed-ridden adult patients at nutritional risk (Nutrition Risk Index <97.5), admitted to medical and surgical departments. Results: Three hundred and ninety-six (28.8%) patients presented vitamin B12 > 1000 pg/mL. Two hundred and four patients died in the hospital (14.9%). The adjusted odds ratio of in-hospital mortality in patients with high vitamin B12 was 2.20 (95% CI, 1.56–3.08; p < 0.001); it was independent of age, gender, body mass index, six-month previous unintentional weight loss, admission ward, presence of malignancy, renal function, C-reactive protein and prealbumin. Patients with high vitamin B12 also had a longer length of stay (LOS) than those with normal concentrations (median 25 days, (IQR 15–41) versus 23 days (IQR 14–36); p = 0.014), and elevated vitamin B12 was an independent predictor of LOS (p = 0.027). Conclusions: An independent association between elevated vitamin B12 concentrations, mortality and LOS was found in our sample of hospitalized adult patients at nutritional risk. Although the underlying mechanisms are still unknown and any cause-effect relation cannot be inferred, clinicians should be aware of the potential negative impact of high vitamin B12 concentrations in hospitalized patients at nutritional risk and avoid inappropriate vitamin supplementation.