The C677T MTHFR genotypes influence the efficacy of B9 and B12 vitamins supplementation to lowering plasma total homocysteine in hemodialysis

Physiological Associations between Vitamin B Deficiency and Diabetic Kidney Disease

The number of people living with chronic kidney disease (CKD) is growing as our global population continues to expand. With aging, diabetes, and cardiovascular disease being major harbingers of kidney disease, the number of people diagnosed with diabetic kidney disease (DKD) has grown concurrently. Poor clinical outcomes in DKD could be influenced by an array of factors-inadequate glycemic control, obesity, metabolic acidosis, anemia, cellular senescence, infection and inflammation, cognitive impairment, reduced physical exercise threshold, and, importantly, malnutrition contributing to protein-energy wasting, sarcopenia, and frailty. Amongst the various causes of malnutrition in DKD, the metabolic mechanisms of vitamin B (B1 (Thiamine), B2 (Riboflavin), B3 (Niacin/Nicotinamide), B5 (Pantothenic Acid), B6 (Pyridoxine), B8 (Biotin), B9 (Folate), and B12 (Cobalamin)) deficiency and its clinical impact has garnered greater scientific interest over the past decade. There remains extensive debate on the biochemical intricacies of vitamin B metabolic pathways and how their deficiencies may affect the development of CKD, diabetes, and subsequently DKD, and vice-versa. Our article provides a review of updated evidence on the biochemical and physiological properties of the vitamin B sub-forms in normal states, and how vitamin B deficiency and defects in their metabolic pathways may influence CKD/DKD pathophysiology, and in reverse how CKD/DKD progression may affect vitamin B metabolism. We hope our article increases awareness of vitamin B deficiency in DKD and the complex physiological associations that exist between vitamin B deficiency, diabetes, and CKD. Further research efforts are needed going forward to address the knowledge gaps on this topic.

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.

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.

Improvement of glucose metabolism in pregnant women through probiotic supplementation depends on gestational diabetes status: meta-analysis

The aim of this study was to assess the effects of probiotic and synbiotic supplementation on glucose metabolism in pregnant women using data from randomized controlled trials. Furthermore, this meta-analysis examines whether the observed effects depend on the presence or absence of gestational diabetes mellitus (GDM), and if the effect is dependent on the type of supplement used (probiotic or synbiotic). We performed a literature search of databases (Medline, Scopus, Web of Knowledge, and Cochrane Library) and identified all relevant randomized controlled trials (RCTs) published prior to May 2019. We compared the effects of probiotic supplementation with the administration of placebos in pregnant women with and without GDM. The systematic review and meta-analysis protocol were registered in the International Prospective Register of Systematic Reviews as number CRD 42019111467. 1119 study participants from 15 selected studies were included. The participants in four studies did not have GDM (being recruited to the study before week 20 of pregnancy) and the participants in the rest of the studies were diagnosed with GDM between weeks 24 and 28 of gestation. The meta-analysis showed that supplementation lowers serum glucose, insulin levels, and HOMA-IR index, but only in pregnant women with GDM. Moreover, both probiotics and synbiotics lower serum insulin level and HOMA-IR index, but the glucose lowering effect is specific only to probiotics and not synbiotics. Probiotic supplementation may improve glucose metabolism in pregnant women with GDM. There is a need for more RCT studies with larger groups to better estimate this effect.

Decisive evidence corroborates a null relationship between MTHFR C677T and chronic kidney disease: A case-control study and a meta-analysis

BACKGROUND

Previous meta-analyses have explored the association between the C677T polymorphism of methyltetrahydrofolate reductase (MTHFR) and chronic kidney disease (CKD) but there were no studies with a decisive conclusion. Furthermore, the high heterogeneity among different populations is not yet interpreted.

OBJECTIVES

This study used trial sequential analysis (TSA) to evaluate whether the nowadays conclusion supported by current cumulative samples. We also applied case-weighted meta-regression to explore the potential gene-environment interactions.

METHODS

For the first stage of this study we conducted a case-control study involving 847 dialysis patients from 7 hemodialysis centers in Taipei during 2015 to 2018 and 755 normal controls from a health center in the Tri-Service General Hospital. The second stage combined the results from the first stage with previous studies. The previous studies were collected from PubMed, EMBASE, and Web of Science databases before January 2018.

RESULTS

From the case-control study, the T allele of MTHFR C677T appeared to have a protective effect on end-stage renal disease compared with the C allele [odds ratio (OR): 0.80, 95% CI (confidence interval) = 0.69-0.93]. However, the meta-analysis contradicted the results in Asian (OR = 1.12, 95% CI = 0.96-1.30). The same analysis was also applied in Caucasian and presented similar results from Asian (OR = 1.18, 95% CI = 0.98-1.42). The TSA showed our case-control study to be the decisive sample leading to a null association among Asian population. The high heterogeneity (I = 75%) could explain the contradictory results between the case-control study and the meta-analysis. However, further case-weighted meta-regression did not find any significant interaction between measured factors and MTHFR C677T on CKD.

CONCLUSIONS

High heterogeneities were found in both Caucasian and Asian, which caused the null relationship in meta-analysis while there were significant effects in individual studies. Future studies should further explore the high heterogeneity that might be hidden in unmeasured gene-environment interactions, to explain the diverse findings among different populations.

Imbalance of Homocysteine and H2S: Significance, Mechanisms, and Therapeutic Promise in Vascular Injury

While the role of hyperhomocysteinemia in cardiovascular pathogenesis continuously draws attention, deficiency of hydrogen sulfide (H₂S) has been growingly implicated in cardiovascular diseases. Generation of H₂S is closely associated with the metabolism of homocysteine via key enzymes such as cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). The level of homocysteine and H₂S is regulated by each other. Metabolic switch in the activity of CBS and CSE may occur with a resultant operating preference change of these enzymes in homocysteine and H₂S metabolism. This paper presented an overview regarding (1) linkage between the metabolism of homocysteine and H₂S, (2) mutual regulation of homocysteine and H₂S, (3) imbalance of homocysteine and H₂S in cardiovascular disorders, (4) mechanisms underlying the protective effect of H₂S against homocysteine-induced vascular injury, and (5) the current status of homocysteine-lowering and H₂S-based therapies for cardiovascular disease. The metabolic imbalance of homocysteine and H₂S renders H₂S/homocysteine ratio a potentially reliable biomarker for cardiovascular disease and development of drugs or interventions targeting the interplay between homocysteine and H₂S to maintain the endogenous balance of these two molecules may hold an even bigger promise for management of vascular disorders than targeting homocysteine or H₂S alone.

Nutritional Supplements During Gestation and Autism Spectrum Disorder: What Do We Really Know and How Far Have We Gone?

Nutritional interventions are gaining remarkable attention as complementary management options for autism. Our aim is to provide literature data about the impact of the administration of dietary supplements during pregnancy on the risk of autism spectrum disorder in the offspring. A comprehensive search was undertaken by 2 reviewers independently using PubMed as the medical database source. Prospective clinical and experimental studies were considered and no year-of-publication restriction was placed. We were able to identify 4 basic (conducted in rodents) and 3 clinical research papers fulfilling our selection criteria. Supplements studied included folic acid, iron, multivitamins, choline, vitamin D, and docosahexaenoic acid. Choline and folic acid had a significant impact on the expression of autism-related genes. However, from a clinical point of view, prenatal folate administration did not reduce the risk of autism. Similarly, iron had no significant impact, while the use of multivitamins in moderate frequency had a protective effect. The use of vitamin D and docosahexaenoic acid during gestation decreased the incidence of autism in animal models. In conclusion, available data are controversial and cannot change current routine practice. More large-scale prospective studies are needed to identify the real effect of nutritional supplements and also optimize their administration.Key teaching pointsMultivitamins use during pregnancy can exert a protective effect on the risk of autism, although depending on the frequency of use. Nevertheless, prenatal iron and folate were not shown to have any significant impact.Research based on animal models showed that choline and folic acid can have a significant impact on the expression of autism-related genes in a sex-specific manner.Furthermore, the use of vitamin D and docosahexaenoic acid during gestation seem to decrease the incidence of autism in animal offspring.In the future, more clinical, large-scale prospective and methodologically homogenous clinical studies are needed to further investigate the effect of the periconceptional use of nutritional supplements on autism risk.

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.

Acute renal infarction in Turkey: a review of 121 cases

PURPOSE

Renal infarction is a clinical condition which is caused by renal artery occlusion and leads to permanent renal parenchymal damage. In the literature, there are generally case reports on this subject, and few studies that include a large group of patients. Therefore, we aimed to present the data of a large group of patients who were diagnosed with acute renal infarction in our country in this retrospective study.

METHODS

The data of patients who were diagnosed with acute renal infarction according to clinical and radiological findings in Turkey in the last 3 years were examined. For this purpose, we contacted with more than 40 centers in 7 regions and obtained support from clinically responsible persons. Demographic data of patients, laboratory data at the time of diagnosis, tests performed for etiologic evaluation, given medications, and patients' clinical status during follow-up were obtained from databases and statistical analysis was performed.

RESULTS

One-hundred and twenty-one patients were included in the study. The mean age was 53 ± 1.4 (19-91) years. Seventy-one (58.7%) patients were male, 18 (14.9%) had diabetes, 53 (43.8%) had hypertension, 36 (30%) had atrial fibrillation (AF), and 6 had a history of lupus + antiphospholipid syndrome (APS). Forty-five patients had right renal infarction, 50 patients had left renal infarction, and 26 (21.5%) patients had bilateral renal infarction. The examinations for the ethiologies revealed that, 36 patients had thromboemboli due to atrial fibrillation, 10 patients had genetic anomalies leading to thrombosis, 9 patients had trauma, 6 patients had lupus + APS, 2 patients had hematologic diseases, and 1 patient had a substance abuse problem. Fifty-seven (57%) patients had unknown. The mean follow-up period was 14 ± 2 months. The mean creatinine and glomerular filtration rate (GFR) values at 3 months were found to be 1.65 ± 0.16 mg/dl and 62 ± 3 ml/min, respectively. The final mean creatinine and GFR values were found to be 1.69 ± 0.16 mg/dl and 62 ± 3 ml/min, respectively.

CONCLUSIONS

Our study is the second largest series published on renal infarction in the literature. More detailed studies are needed to determine the etiological causes of acute renal infarction occurring in patients.

Relationship between plasma levels of homocysteine and the related B vitamins in patients with hemodialysis adequacy or inadequacy

OBJECTIVES

Hemodialysis (HD) with dialysis adequacy could increase the excretion of B vitamins (folate, vitamin B₆, and B₁₂) and raise the plasma level of homocysteine. Here we determined the associations of plasma homocysteine with B vitamins in patients with HD adequacy or inadequacy.

METHODS

We recruited 68 patients who had received HD treatments (three times a week, 4 h each). Based on the individual's hemogram and quarterly urea reduction rate (Kt/V), patients were pooled into one of the following two groups: the first group with dialysis adequacy (Kt/V > 1.2, n = 48) and the second with dialysis inadequacy (Kt/V ≤ 1.2, n = 20). We also recorded the anthropometric date of each patient and their biochemical data and dietary intakes. Plasma levels of homocysteine, cysteine, folate, pyridoxal 5'-phosphate (PLP), and vitamin B₁₂ were measured twice, once before and once after HD.

RESULTS

The plasma levels of homocysteine, cysteine, folate, PLP, and vitamin B₁₂ dropped significantly at the end of HD. The plasma levels of vitamin B₁₂ were negatively correlated with the plasma levels of homocysteine, both pre- and post-HD, and in both groups regardless of dialysis adequacy or inadequacy. In contrast, plasma levels of folate and PLP were not correlated with homocysteine at both pre- or post-HD in both groups.

CONCLUSIONS

The plasma level of vitamin B₁₂, but not folate or vitamin B₆, was negatively correlated with that of homocysteine both before and after HD treatment, and regardless of dialysis adequacy or inadequacy.

Hypermethylation: Causes and Consequences in Skeletal Muscle Myopathy

A detrimental consequence of hypermethylation is hyperhomocysteinemia (HHcy), that causes oxidative stress, inflammation, and matrix degradation, which leads to multi-pathology in different organs. Although, it is well known that hypermethylation leads to overall gene silencing and hypomethylation leads to overall gene activation, the role of such process in skeletal muscle dysfunction during HHcy condition is unclear. In this study, we emphasized the multiple mechanisms including epigenetic alteration by which HHcy causes skeletal muscle myopathy. This review also highlights possible role of methylation, histone modification, and RNA interference in skeletal muscle dysfunction during HHcy condition and potential therapeutic molecules, putative challenges, and methodologies to deal with HHcy mediated skeletal muscle dysfunction. We also highlighted that B vitamins (mainly B12 and B6), with folic acid supplementation, could be useful as an adjuvant therapy to reverse these consequences associated with this HHcy conditions in skeletal muscle. However, we would recommend to further study involving long-term trials could help to assess efficacy of the use of these therapeutic agents. J. Cell. Biochem. 118: 2108-2117, 2017. © 2017 Wiley Periodicals, Inc.