Diagnostic accuracy of holotranscobalamin, methylmalonic acid, serum cobalamin, and other indicators of tissue vitamin B₁₂ status in the elderly

Ultrasensitive detection of holoTC for analysis of Vitamin B12 levels using Ag2MoO4 deposited PEDOT sensing platform

Vitamin B12 is an essential micronutrient required for the proper functioning of the human body. Vitamin B12 deficiency is primarily causative of various neurolological disorders alongwith recurrence of oral ulcers and burning sensations which are early signs of condition such as pernicious anemia. Other complications associated with Vitamin B12 deficiency include risk of heart failure due to anemia, risk of developing autoimmune disorders and gastric cancer. Therefore, to obstruct these communal health issues, early detection of Vit B12 is highly needed. However, screening of vitamin B12 insufficiency is hindered by the low sensitivity of the conventional vitamin B12 test. Holotranscobalamin (holoTC) is an early indicator of the negative vitamin B12 balance as it is the first protein to decline in the serum. We report a novel impedimetric immunosensor based on flower-like poly (3,4-ethylenedioxythiophene) (PEDOT) nanostructural film impregnated with silver molybdate nanoparticles (Ag2MoO₄ NPs) deposited on fluorine-doped tin oxide electrode. The prepared electrodes were characterized by Field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and electrochemical studies. The activated anti-holoTC antibody was immobilized and optimized to capture the target in a response time of 15 min. The electrochemical performance of the sensor was carried out by using the electrochemical impedance spectroscopy technique (EIS) and a good linear relationship between ΔRct and holoTC was obtained in the range from 0.1 pg mL-1 to 100 ng mL-1 with a detection limit of 0.093 pg mL-1. The proposed sensor was successfully applied in human serum samples for holoTC detection. The experimental results showed that the immunosensor is highly selective towards holoTC and presented an acceptable stability of 20 days with reproducibility RSD ≤4%. To the best of our knowledge, this is the first developed electrochemical immunosensor for holoTC detection.

Vitamin B12 Status and Supplementation in Plant-Based Diets

Plant-based diets are increasingly popular worldwide. A well-planned plant-based diet lowers the risk of cardiovascular disease, type 2 diabetes and certain cancers. In contrast, a poorly planned plant-based diet increases the risk of certain micronutrient deficiencies, chiefly, vitamin B12 (B12). Because B12 is not present in plants or in unfortified plant-based foodstuffs, the safest way to prevent its deficiency in plant-based diets is to take an oral B12 supplement. Studies determining the dose and frequency of B12 to be taken by healthy individuals on a plant-based diet to support an adequate B12 status are scarce. Here, we summarize the natural sources, metabolic requirements, biomarker findings with and without supplementation with B12, and current recommendations to help prevent vitamin B12 deficiency in healthy individuals adhering or transitioning to plant-based diets. This review focuses on the prevention of vitamin B12 deficiency in healthy individuals adhering to plant-based diets. The information covered in this review does not apply to individuals suffering from autoimmune-based malabsorption of vitamin B12 resulting from pernicious anemia due to atrophic gastritis, other acquired causes of B12 malabsorption or to those with genetic disorders that impair vitamin B12 absorption, transport and utilization.

A micronutrient supplement modulates homocysteine levels regardless of vitamin B biostatus in elderly subjects

Elevated homocysteine (Hcy) levels (≥15 μmol/L) in the elderly are frequently associated with a higher risk of cardiovascular disease and cognitive decline. Several studies have already shown an Hcy-lowering effect of B vitamin supplementation in cohorts deficient in these nutrients. The aim of this randomized, double-blinded 12-week intervention study was to investigate whether Hcy levels in healthy elderly subjects (75.4±4.5 years, n=133) could be lowered with a micronutrient supplement (i.e., 400 μg folic acid, 100 μg cobalamin). Difference in mean initial Hcy levels between intervention (17.6±7.1 μmol/L, n=65) and placebo group (18.9±6.1 μmol/L, n=68) was not significant. The prevalence of cobalamin and folate deficiency in the total study population was low: 27% had serum-cobalamin levels ≤150 pmol/L, 12% holo-transcobalamin (Holo-TC) levels ≤50 pmol/L, 13% low cobalamin status using the aggregated cobalamin marker 4cB12 and 10% red blood cell (RBC) folate ≤570 nmol/L. Nevertheless, the treated subjects still showed improved cobalamin and folate biostatus (serum cobalamin Δt12-t0: 63±48 pmol/L; Holo-TC Δt12-t0: 17±19 pmol/L; RBC folate Δt12-t0: 326±253 nmol/L) and Hcy levels (Δt12-t0: -3.6±5.7 μmol/L). The effects were statistically significant compared to the placebo group with p=0.005 (serum cobalamin), p=0.021 (Holo-TC), p=0.014 (RBC-folate) and p<0.001 (Hcy). The Hcy-lowering effect was dependent on the initial Hcy levels (p<0.001). Our findings suggest that elevated Hcy levels in elderly subjects can be lowered regardless of the initial cobalamin and folate biostatus.

Preliminary evaluation of the diagnostic performance of Roche Elecsys® active vitamin B12 versus total vitamin B12 for vitamin B12 deficiency screening

INTRODUCTION

The prevalence of vitamin B12 deficiency is high in at-risk populations with sometimes irreversible consequences. Beside total B12 (TVB12), active B12 (AVB12) is a promising first-line marker. Only Abbott AVB12 assays were largely evaluated and generally demonstrated benefit in clinical practice. More recently developed Roche AVB12 still requires some investigations.

OBJECTIVES

Our study aimed to evaluate the Roche Elecsys® AVB12 immunoassay performance versus Roche Elecsys® TVB12 competition assay.

DESIGN

and Methods: We included 175 patients at Rouen University Hospital who had a TVB12 value <300 pmol/L. We evaluated performance of AVB12 by comparing the results with TVB12 and MMA values in case of disagreement.

RESULTS

Positive correlation was found between the AVB12 and TVB12. We found a disagreement between TVB12 and AVB12 in 18.8% of cases. Among 33 cases of disagreement, 76% had normal AVB12 but low TVB12, whereas 24% had low AVB12 and normal TVB12. Thirty-one MMA determinations were performed: 71% showed agreement between MMA and AVB12, versus 29% between MMA and TVB12. TVB12 reported a sensitivity (Se) at 66.7%, specificity (Sp) at 20%, positive predictive value (PPV) at 16.7% and negative predictive value (NPV) at 71.4% for the prediction of MMA elevation. We determined an optimized cut-off value of 45.5 pmol/L for AVB12, which reported a Se 66.7%, Sp 60%, PPV 30.7%, and NPV 88.9%.

CONCLUSIONS

Our results provide preliminary evidence that Roche AVB12 may offer better discrimination than Roche TVB12 in the diagnosis of vitamin B12 deficiency. Further more detailed evaluation is warranted.

The Impact of Clinical Factors, Vitamin B12 and Total Cholesterol on Severity of Anorexia Nervosa: A Multicentric Cross-Sectional Study

Severe forms of Anorexia Nervosa (AN) are characterized by medical complications, psychiatric comorbidity, and high mortality. This study investigated potential associations between clinical/biological factors and the severity of AN, measured by the Body Mass Index (BMI). Red and white blood cells, hemoglobin, platelets, iron, vitamins D and B12, folate, and total cholesterol were measured in a mixed sample of 78 inpatients and outpatients. Linear regressions and one-way analyses of variance (ANOVAs) were carried out to evaluate the relationship between BMI and clinical/biochemical variables. BMI was significantly lower in hospitalized patients (F = 4.662; p = 0.034) and in those under pharmacological treatment (F = 5.733; p = 0.019) or poly-therapy (F = 5.635; p = 0.021). Higher vitamin B12 (β = -0.556, p < 0.001), total cholesterol (β = -0.320, p = 0.027), and later age at onset (with a trend towards significance) (β = -0.376, p = 0.058) were associated with a lower BMI. Increased total cholesterol and vitamin B12, later age at onset, current pharmacological treatment, and poly-therapy might be distinctive in patients with a lower BMI. In clinical practice, these findings may contribute to the early identification of AN patients at higher risk of developing complicated or chronic forms of the disorder. Further studies on larger samples are needed to identify potential predictive factors of AN severity in the framework of precision medicine.

Nutritional status of flexitarians compared to vegans and omnivores - a cross-sectional pilot study

BACKGROUND

In the Western world, there has been a notable rise in the popularity of plant-based, meat-reduced flexitarian diets. Nevertheless, there is insufficient data on the nutritional status of individuals following this dietary pattern. The aim of this study was to investigate the intake and endogenous status of various nutrients in a healthy German adult study population consisting of flexitarians (FXs), vegans (Vs) and omnivores (OMNs).

METHODS

In this cross-sectional study, dietary intake of 94 non-smoking adults (32 FXs, 33 Vs, 29 OMNs) between 25 and 45 years of age was assessed using 3-day dietary records. In addition, blood samples were collected to determine different endogenous nutrient status markers.

RESULTS

32%, 82% and 24% of the FXs, Vs, and OMNs respectively reported using dietary supplements. In the FXs, intake of total energy as well as macronutrients and most micronutrients were within the reference range. FXs had higher intakes of fiber, retinol-equ., ascorbic acid, folate-equ., tocopherol-equ., calcium, and magnesium compared to OMNs. However, cobalamin intake in FXs (2.12 µg/d) was below the reference (4 µg/d). Based on 4cB12, 13% of FXs showed a cobalamin undersupply [< -0.5 to -2.5] compared to 10% of OMNs, and 9% of Vs. The median 25(OH)D serum concentrations in FXs, Vs and OMNs were 46.6, 55.6, and 59.6 nmol/L. The prevalence of an insufficient/deficient vitamin-D status [< 49.9 nmol 25(OH)D/L] was highest in FXs (53%), followed by Vs (34%) and OMNs (27%). In FXs and Vs, the supplement takers had better cobalamin and vitamin-D status than non-supplement takers. Anemia and depleted iron stores were found only occasionally in all groups. In women, the prevalence of pre-latent iron deficiency and iron deficiency was highest in FXs (67%) compared to Vs (61%) and OMNs (54%).

CONCLUSION

Our findings indicated that all three diets delivered sufficient amounts of most macro- and micronutrients. However, deficiencies in cobalamin, vitamin-D, and iron status were common across all diets. Further studies are needed to investigate the nutrient supply status and health consequences of meat-reduced plant-based diets. The study was registered in the German Clinical Trial Register (number: DRKS 00019887, data: 08.01.2020).

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.

Vitamin B12 status in term pregnant women and the cord blood samples of their newborns: A cross-sectional study

Background and aim: In India, total vitamin B12 (Vit B12) and its active form (active B12) have not been studied in mother's blood and cord blood. We hypothesized that total and active B12 levels are sufficiently maintained in cord blood despite low levels in mothers. Methods: Two hundred term pregnant mother's blood and cord blood was collected and analyzed for total Vit B12 (radioimmunoassay method) and active B12 levels (enzyme-linked immunosorbent assay). Mean values of constant or continuous variables (hemoglobin (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), white blood cells (WBC), and Vit B12) were compared in mother's blood and newborn cord blood using Student's t-test and multiple comparisons within the groups were carried out with ANOVA. Spearman's correlation (Vit B12) and multivariable backward regression analyses (height, weight, education, body mass index (BMI) and Hb, PCV, MCV, WBC, and Vit B12 levels) were also performed. Results: Total Vit 12 deficiency was highly prevalent at 89% and active B12 deficiency was 36.7% in mothers. Cord blood showed total Vit B12 deficiency prevalence of 53% and active B12 deficiency being 9.3%. Total Vit B12 (p<0.001) and active B12 (p<0.001) levels were significantly higher in cord blood when compared to mother's blood. In multivariate analysis, higher total and active B12 levels in mother's blood predicted higher levels of total and active B12 levels in cord blood. Conclusion: Our study showed higher prevalence of total and active Vit B12 deficiency in mothers compared to cord blood thus indicating their transfer to fetus irrespective of mother's status. Maternal Vit B12 levels affected cord blood Vit B12 levels.

Comparison of Serum Holotranscobalamin with Serum Vitamin B12 in Population Prone to Megaloblastic Anemia and their Correlation with Nerve Conduction Study

Early detection of megaloblastic anemia and associated neurological complications is crucial for management. This study was conducted to compare serum holotranscobalamin level with serum vitamin B12 level as early biomarker in people prone to megaloblastic anemia and to evaluate co-relation between these biomarkers and nerve conduction study in study patients. 83 adult patients (Hb > 12 gm/dl) prone to megaloblastic anemia were studied for basic haematological investigations, random blood sugar, thyroid function test, liver function test, kidney function test, serum vitamin B12, serum holotranscobalamin and serum folic acid levels. 45 patients among them underwent nerve conduction studies. All study patients were classified in 6 groups on the basis of risk factors for megaloblastic anemia. 29 patients (34.9%) were on antiepileptic drugs, 26 (31.3%) were chronic alcoholic, 10 patients (12%) each, had malabsorption and ileal tuberculosis, 6 (7.22%) had chronic pancreatitis and 2 (2.4%) had ileal resection. 30 patients (36.14%) had low serum holotranscobalamin, including 7 patients (8.43%) with low serum vitamin B12 level also, unmasking vitamin B12 deficiency in 23 patients (27.7%). 7 patients (8.43%) had mean corpuscular volume (MCV) > 100fL and 8 patients (9.63%) had vitamin B12 deficiency related changes on peripheral smear. Serum vitamin B12 and holotranscobalamin levels were significantly low in patients with peripheral smear changes, with p value 0.039 and 0.041 respectively, while no such association seen with MCV. Subclinical peripheral neuropathy was detected in 18 (40%) out of 45 patients on nerve conduction study. Serum holotranscobalamin levels were significantly lower (p = 0.031) than serum vitamin B12 levels (p = 0.2) in patients with neuropathic changes. Rest investigations and serum folic acid levels were normal in all patients. Holotranscobalamin levels can be considered early and reliable marker for vitamin B12 deficiency and deficiency associated peripheral neuropathy, even in patients who are prone to megaloblastic anemia, and not yet anemic or symptomatic for neuropathy.

A Rapid, Simple, Trace, Cost-Effective, and High-Throughput Stable Isotope-Dilution Liquid Chromatography-Tandem Mass Spectrometry Method for Serum Methylmalonic Acid Quantification and Its Clinical Applications

Background: Methylmalonic acid (MMA) is an essential indicator of vitamin B12 (VB12) deficiency and inherited metabolic disorders (IMDs). The increasing number of requests for MMA testing call for higher requirements for convenient MMA testing methods. This study aims to develop a convenient quantification method for serum MMA. Methods: The method was established based on the stable isotope-dilution liquid chromatography−tandem mass spectroscopy (ID-LC-MS/MS) technique. The LC-MS/MS parameters and sample preparation were optimized. Specificity, sensitivity, robustness, accuracy, and clinical applicability were validated according to CLSI C62-A guidelines. MMA levels in VB12-sufficient subjects and VB12-deficient subjects were measured. Results: MMA and its intrinsic isomer, i.e., succinic acid (SA), were completely separated. The average slope, intercept, and correlation relationship (R) with 95% confidence intervals, during the two months, were 0.992 (0.926−1.059), −0.004 (−0.012−0.004), and 0.997 (0.995−0.999), respectively. The limit of detection and quantification were <0.058 μmol/L and 0.085 μmol/L, respectively. Intra-run, inter-run, and total imprecisions were 1.42−2.69%, 3.09−5.27%, and 3.22−5.47%, respectively. The mean spiked recoveries at the three levels were 101.51%, 92.40%, and 105.95%, respectively. The IS-corrected matrix effects were small. The VB12-deficient subjects showed higher MMA levels than VB12-sufficient subjects. Conclusions: A convenient LC-MS/MS method for serum MMA measurement was developed and validated, which could be suitable for large-scale MMA testing and evaluating MMA levels in VB12-deficient patients.

Liver and vitamin B12 parameters in patients with anorexia nervosa before and after short-term weight restoration

Hepatic involvement in anorexia nervosa (AN) has been previously reported, but a link to elevated vitamin B₁₂ concentrations, which can be a sign for liver damage, has not been thoroughly examined. We measured liver enzymes (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase) and vitamin B₁₂ parameters (total B₁₂, holotranscobalamin, methylmalonic acid) in the plasma of young female patients with acute AN (n=77) and after short-term weight restoration (n=58, median body mass increase=25%), in comparison to healthy control participants (n=63). For a comprehensive assessment of vitamin B₁₂ status, the combined marker cB₁₂ was calculated. In acute AN, activities of alanine aminotransferase and gamma-glutamyltransferase as well as holotranscobalamin concentrations were elevated, and alanine aminotransferase activities positively correlated with total B₁₂, holotranscobalamin and cB₁₂ in patients with elevated liver enzyme activities. After weight restoration, alanine aminotransferase activities and holotranscobalamin concentrations were elevated, and cB₁₂ increased above the level of the healthy control group. The present study provides further evidence for a hepatic involvement in acute AN in concert with vitamin B₁₂ parameters and points to refeeding-associated alterations of liver and vitamin B₁₂ parameters. Future studies should include non-invasive methods to characterize hepatic involvement and evaluate vitamin B₁₂ status as a potential marker of liver damage/irritation.

B12 vitamin eksikliği olan kişilerin tam kan, ortalama trombosit hacmi (MPV) ve nötrofil-lenfosit oranlarının (NLR) değerlendirilmesi

Giriş: B12 vitamin eksikliğinin; kan tetkiklerine, ortalama trombosit hacmine (MPV) ve inflamasyon markerlarından nötrofil-lenfosit oranına (NLR) etkilerinin araştırılması amaçlanmıştır.Yöntem: Çalışmamız 375 hasta üzerinde yapılmıştır. B12’si düşük (&lt;130 pg/dL) saptanan 170 hasta deney grubu olarak, B12 düzeyleri normal olan 205 kişide kontrol grubu olarak kabul edilmiştir. Bu iki grup arasında beyaz kan hücreleri (WBC), trombosit sayısı (Plt), hemoglobin (Hgb), ortalama eritrosit hacmi (MCV), MPV, nötrofil, lenfosit sayıları ve nötrofil-lenfosit oranları (NLR) incelenmiştir.Bulgular: Yaş ortalaması B12 eksik grupta 48.45 ±17.497 yıl, kontrol grubunda ise 51.93 ±16.175 yıl idi. Eksik grupta B12vitamini ortalaması 101,41 ± 20,50 pg/mL (min-max; 37-130), kontrol grubunda ise 257,24 ± 88,13 pg/mL (min-max; 131-498) idi. WBC, Hgb, Plt, nötrofil, lenfosit, MVC, MPV ve NLR arasında istatiksel açıdan anlamlı bir fark olmadığı gözlendi.Sonuç: Çalışmamızda B12 eksikliği ile kan tetkikleri arasında anlamlı bir ilişki bulamadık. Önceki çalışmalarda B12 eksikliğinde MPV değerlerinin etkilendiğine dair bilgiler bulunmaktadır. Yaptığımız çalışmada da B12 eksikliği ile MPV ve NLR arasında anlamlı bir ilişkinin olmadığını saptadık (p&gt;0,05). B12 eksikliğinin derecesi ve süresi uzadıkça nasıl değişiklikler meydana geleceği ve özellikle de aterojenik olaylara etkisi hakkında yapılacak yeni çalışmalara ihtiyaç vardır. 

Does Metformin Treatment in Pediatric Population Cause Vitamin B12 Deficiency?

BACKGROUND/AIM

There have been no studies to date examining the effect of metformin treatment on vitamin B12 status in children and adolescents. In this prospective study, the effects of metformin on blood vitamin B12, serum methylmalonic acid (MMA), homocysteine and holo-transcobalamin-II (holo-TC-II) levels were assessed in pediatric age group.

MATERIALS AND METHODS

This prospective study was conducted at the Pediatric Endocrinology and Adolescent Department between January 2017 and March 2019. Metabolic syndrome and polycystic ovary syndrome diagnosed patients with insulin resistance and/or impaired glucose tolerance, patients with type 2 diabetes mellitus (DM) treated with metformin were enrolled in study. Blood vitamin B12, MMA, homocysteine, holo-TC-II levels and hemogram values were evaluated.

RESULTS

Twenty-four patients were enrolled in study. Among these, 15 (62.5%) were female. The mean age of patients was 13.7±2.3 (10-19) years. Sixteen patients were diagnosed with metabolic syndrome and 8 patients were type 2 DM. At 6-month follow-up of all patients, there was no statistically significant difference in terms of vitamin B12, homocysteine, MMA and holo-TC-II levels. A 0.6% decline in vitamin B12 levels were revealed. At 12-month follow-up of 11 patients (45.8%) (6 Type 2 DM, 5 metabolic syndrome), no statistically significant difference was determined in vitamin B12, homocysteine, MMA and holo-TC-II levels. There were 6% decline in vitamin B12 levels and 10.9% increase in homocysteine levels, 5.4% decrease was detected in holo-TC-II level.

CONCLUSION

Although no significant changes in the serum vitamin B12, homocysteine, MMA or holo-TC-II levels with metformin therapy were detected, long-term prospective studies with high-dose metformin treatment in pediatric population are needed to confirm our results.

Personalising laboratory medicine in the 'real world': Assessing clinical utility, by clinical indication, of serum total B12 and Active-B12® (holotranscobalamin) in the diagnosis of vitamin B12 deficiency

BACKGROUND

Assessing the pre- and post-test probability of disease in the context of routine health care is challenging. We wished to study how test performance parameters relating to clinical utility vary by clinical indication in a 'real-world' setting.

METHODS

The diagnostic accuracy of serum total B12 and Active-B12® (holotranscobalamin) was evaluated in a primary care population, using serum methylmalonic acid as the reference standard. We used electronic requesting to establish the clinical indication for each request. Routine requests from primary care for serum total B12 were included if creatinine was also measured and estimated glomerular filtration rate was at least 60 mL/min/1.73 m2.

RESULTS

Clinical indications included peripheral neuropathy (n = 168), anaemia (n = 168), cognitive decline (n = 125), suspected dietary deficiency (n = 76), other (n = 362). For peripheral neuropathy, the area under the receiver operator curve ± 95% confidence interval (AUC ± CI) was 0.63 (0.54-0.71) (P = 0.002) for total B12 and 0.68 (0.60-0.77) (P < 0.0001) for Active-B12®. For anaemia, AUC ± CI was 0.56 (0.47-0.66) (P = 0.10) for total B12 and 0.69 (0.59-0.78) (P < 0.0001) for Active-B12®. For cognitive decline, AUC ± CI was 0.54 (0.43-0.65) (P = 0.26) for total B12 and 0.69 (0.58-0.80) (P = 0.0002) for Active-B12®. The pre-post-test change in probability of disease varied by clinical indication.

CONCLUSION

Combining diagnostic accuracy studies and electronic testing in a 'real-world' setting allows clinical utility to be assessed by clinical indication. Wider application of this would permit more personalised laboratory medicine. In this study, diagnostic performance of total B12 and Active-B12® varied across all indications. Active-B12® provided better discrimination, but this may have reflected the cut-offs used.

The snapshot of metabolic health in evaluating micronutrient status, the risk of infection and clinical outcome of COVID-19

COVID-19 has re-established the significance of analyzing the organism through a metabolic perspective to uncover the dynamic interconnections within the biological systems. The role of micronutrient status and metabolic health emerge as pivotal in COVID-19 pathogenesis and the immune system's response. Metabolic disruption, proceeding from modifiable factors, has been proposed as a significant risk factor accounting for infection susceptibility, disease severity and risk for post-COVID complications. Metabolomics, the comprehensive study and quantification of intermediates and products of metabolism, is a rapidly evolving field and a novel tool in biomarker discovery. In this article, we propose that leveraging insulin resistance biomarkers along with biomarkers of micronutrient deficiencies, will allow for a diagnostic window and provide functional therapeutic targets. Specifically, metabolomics can be applied as: a. At-home test to assess the risk of infection and propose nutritional support, b. A screening tool for high-risk COVID-19 patients to develop serious illness during hospital admission and prioritize medical support, c(i). A tool to match nutritional support with specific nutrient requirements for mildly ill patients to reduce the risk for hospitalization, and c(ii). for critically ill patients to reduce recovery time and risk of post-COVID complications, d. At-home test to monitor metabolic health and reduce post-COVID symptomatology. Metabolic rewiring offers potential virtues towards disease prevention, dissection of high-risk patients, taking actionable therapeutic measures, as well as shielding against post-COVID syndrome.

Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial

AIM

To investigate the effect of normalizing vitamin B12 (B12) levels with oral B12 (methylcobalamin) 1000 μg/day for one year in patients with diabetic neuropathy (DN).

PATIENTS AND METHODS

In this prospective, double-blind, placebo-controlled trial, 90 patients with type 2 diabetes on metformin for at least four years and both peripheral and autonomic DN were randomized to an active treatment group (n = 44) receiving B12 and a control group (n = 46) receiving a placebo. All patients had B12 levels less than 400 pmol/L. Subjects underwent measurements of sural nerve conduction velocity (SNCV), sural nerve action potential (amplitude) (SNAP), and vibration perception threshold (VPT), and they performed cardiovascular autonomic reflex tests (CARTs: mean circular resultant (MCR), Valsalva test, postural index, and orthostatic hypotension). Sudomotor function was assessed with the SUDOSCAN that measures electrochemical skin conductance in hands and feet (ESCH and ESCF, respectively). We also used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE, respectively) and questionnaires to evaluate quality of life (QoL) and level of pain (pain score).

RESULTS

B12 levels increased from 232.0 ± 71.8 at baseline to 776.7 ± 242.3 pmol/L at follow-up, p < 0.0001, in the active group but not in the control group. VPT, MNSIQ, QoL, pain score, SNCV, SNAP, and ESCF significantly improved in the active group (p < 0.001, p = 0.002, p < 0.0001, p < 0.000, p < 0.0001, p < 0.0001, and p = 0.014, respectively), whereas CARTS and MNSIE improved but not significantly. MCR, MNSIQ, SNCV, SNAP, and pain score significantly deteriorated in the control group (p = 0.025, p = 0.017, p = 0.045, p < 0.0001, and p < 0.0001, respectively).

CONCLUSIONS

The treatment of patients with DN with 1 mg of oral methylcobalamin for twelve months increased plasma B12 levels and improved all neurophysiological parameters, sudomotor function, pain score, and QoL, but it did not improve CARTS and MNSIE.

Efficacy and Safety of the Combination of Superoxide Dismutase, Alpha Lipoic Acid, Vitamin B12, and Carnitine for 12 Months in Patients with Diabetic Neuropathy

Aim: To investigate the efficacy of Superoxide Dismutase, Alpha Lipoic Acid, Acetyl L-Carnitine, and Vitamin B12 (B12) in one tablet in Diabetic Neuropathy (DN). Patients–methods: In this prospective, double-blind, placebo-controlled study, 85 patients with Diabetes Mellitus Type 2 (DMT2) were randomly assigned, either to receive the combination of four elements (active group, n = 43), or placebo (n = 42) for 12 months. We used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE), measured the vibration perception threshold (BIO), and Cardiovascular Autonomic Reflex Tests (CARTs). Nerve function was assessed by DPN Check [sural nerve conduction velocity (SNCV) and amplitude (SNAP)]. Pain (PS) and quality of life (QL) questionnaires were administered. Results: At follow-up, BIO, MNSIQ, QL, PAIN, and SNCV, SNAP, and B12 levels had significantly improved inactive group (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.027, p = 0.031, and p < 0.001 respectively), whereas the inplacebo group MCR (mean circular resultant) and PAIN deteriorated (p < 0.001, p < 0.001). The changes in MNSIQ, QL, SNCV, BIO, and PAIN differed significantly between groups (p < 0.001, p < 0.001, p = 0.031, p < 0.001, and p < 0.001 respectively). Conclusions: The combination of the four elements in one tablet for 12 months in patients with DMT2 improved all indices of peripheral neuropathy, including SNAP and SNCV, pain, and Quality of Life perception, except CARTs and MNSIE.

Plasma concentrations of vitamin B12 and folate and global cognitive function in an older population: cross-sectional findings from The Irish Longitudinal Study on Ageing (TILDA)

The uncertainty surrounding high intakes of folic acid and associations with cognitive decline in older adults with low vitamin B12 status has been an obstacle to mandatory folic acid fortification for many years. We estimated the prevalence of combinations of low/normal/high vitamin B12 and folate status and compared associations with global cognitive function using two approaches, of individuals in a population-based study of those aged ≥50 years in the Republic of Ireland. Cross-sectional data from 3781 men and women from Wave 1 of The Irish Longitudinal Study on Ageing were analysed. Global cognitive function was assessed by the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Prevalence estimates for combinations of vitamin B12 (plasma vitamin B12 < or ≥258 pmol/l) and folate (plasma folate ≤ or >45·3 nmol/l) concentrations were generated. Negative binomial regression models were used to investigate the associations of vitamin B12 and folate status with global cognitive function. Of the participants, 1·5 % (n 51) had low vitamin B12 (<258 pmol/l) and high folate (>45·3 nmol/l) status. Global cognitive performance was not significantly reduced in these individuals when compared with those with normal status for both B-vitamins (n 2433). Those with normal vitamin B12/high folate status (7·6 %) had better cognitive performance (MMSE: incidence rate ratio (IRR) 0·82, 95 % CI 0·68, 0·99; P = 0·043, MoCA: IRR 0·89, 95 % CI 0·80, 0·99; P = 0·025). We demonstrated that high folate status was not associated with lower cognitive scores in older adults with low vitamin B12 status. These findings provide important safety information that could guide fortification policy recommendations in Europe.

Vitamin B12 Status and Optimal Range for Hemoglobin Formation in Elite Athletes

Background: Athletes and coaches believe in the ergogenic effect of vitamin B₁₂ (which results from enhanced erythropoiesis) and they often insist on its unjustified supplementation. Therefore, our study aimed to assess the vitamin B₁₂ status in Polish elite athletes and its influence on red blood cell parameters. Methods: In total, 1131 blood samples were collected during six years from 243 track and field athletes divided into strength and endurance groups, as well as according to the declared use of vitamin B₁₂ injections. Results: An average vitamin B₁₂ concentration in all subjects was 739 ± 13 pg/mL, with no cases of deficiency. A weak but significant relationship was found between vitamin B₁₂ and hemoglobin concentrations. A significant increase in hemoglobin appeared from very low vitamin B₁₂ concentration and up to approx. 400 pg/mL, while hemoglobin did not significantly change from 700 pg/mL and onwards. Vitamin B₁₂ injections were used by 34% of athletes, significantly more often by endurance than by strength athletes. In athletes who declared no use of injections, a higher concentration of vitamin B₁₂ was observed in the endurance group. Conclusion: The main finding of the present study is the determination of the range of vitamin B₁₂ concentration which may favor better hemoglobin synthesis in athletes. They should regularly monitor vitamin B₁₂ concentration and maintain the range of 400–700 pg/mL as it may improve red blood cell parameters. We might suggest application of a supplementation if necessary. Special attention is required in athletes with a vitamin B₁₂ concentration below 400 pg/mL.

Diagnostic Accuracy of Holotranscobalamin, Vitamin B12, Methylmalonic Acid, and Homocysteine in Detecting B12 Deficiency in a Large, Mixed Patient Population

Four biomarkers are commonly employed to diagnose B12 deficiency: vitamin B12 (B12), holotranscobalamin (HoloTC), methylmalonic acid (MMA), and homocysteine (Hcy). 4cB12, a combined index of the B12 status, has been suggested to improve the recognition of B12 deficiency. We aimed to evaluate the four different markers for detecting B12 deficiency, as determined by 4cB12. Within a large, mixed patient population, 11,833 samples had concurrent measurements of B12, HoloTC, MMA, and Hcy. 4cB12 was calculated according to the methods described by Fedosov. Diagnostic cutoffs as well as diagnostic accuracy for the detection of B12 deficiency were assessed with receiver operating characteristic (ROC) analysis. The median age was 56 years, and women accounted for 58.8% of the samples. Overall, the area under the curve (AUC) for the detection of subclinical B12 deficiency was highest for HoloTC (0.92), followed by MMA (0.91), B12 (0.9) and Hcy (0.78). The difference between HoloTC and B12 was driven by a significantly higher AUC for HoloTC (0.93) than for B12 (0.89), MMA (0.91), and Hcy in women 50 years and older (0.79; p < 0.05 for all). In the detection of subclinical B12 deficiency, there were no significant differences in the AUCs of HoloTC, B12, and MMA among men and women <50 years. In conclusion, in women < 50 years and in men, HoloTC, MMA, or Hcy do not appear superior to B12 for the detection of B12 deficiency. For women 50 years and older, HoloTC seems to be the preferred first-line marker for the detection of subclinical B12 deficiency.

What is the cobalamin status among vegetarians and vegans in Australia?

Water-soluble vitamin B12 (cobalamin) plays a vital role in normal blood function and neurological functioning. Clinical and subclinical B12 deficiency has been notably reported in vegans, vegetarians, the elderly and metformin-treated diabetics. Currently, the prevalence of cobalamin deficiency among vegans and vegetarians in Australia is lacking; data on dietary intake including supplements and nutritional status are also limited. The increasing multiculturalism of Australia has seen an influx of imported foods, of which some may contain considerable vitamin B12. However, values for such foods are not included in the food composition databases. This review highlights the need to update the food composition database with culturally diverse foods containing vitamin B12. Moreover, the need for assessing dietary intakes and status using the most current best evidence and best practice on nutritional indicators (biochemical and functional biomarkers) to estimate the risk of deficiency and/or depletion is discussed.

The Bayesian Approach to Decision Making and Analysis in Nutrition Research and Practice

This is part of a series of monographs on research design and analysis. The purpose of this article is to describe the purposes of and approach to conducting Bayesian decision making and analysis. Bayesian decision making involves basing decisions on the probability of a successful outcome, where this probability is informed by both prior information and new evidence the decision maker obtains. The statistical analysis that underlies the calculation of these probabilities is Bayesian analysis. In recent years, the Bayesian approach has been applied more commonly in both nutrition research and clinical decision making, and registered dietitian nutritionists would benefit from gaining a deeper understanding of this approach. This article provides a background of Bayesian decision making and analysis, and then presents applications of the approach in two different areas-medical diagnoses and nutrition policy research. It concludes with a description of how Bayesian decision making may be used in everyday life to allow each of us to appropriately weigh established beliefs and prior knowledge with new data and information in order to make well-informed and wise decisions.

Voluntary fortification is ineffective to maintain the vitamin B12 and folate status of older Irish adults: evidence from the Irish Longitudinal Study on Ageing (TILDA)

Mandatory fortification of staple grains with folic acid and/or vitamin B12 (B12) is under debate in many countries including Ireland, which has a liberal, but voluntary, fortification policy. Older adults can be at risk of both deficiency and high folate status, although little is known on the actual prevalence and the major predictors. Population prevalence estimates from older adults (n 5290 ≥50 years) from the Irish Longitudinal Study on Ageing (TILDA) (Wave 1) are presented here. Measures included plasma total vitamin B12 and folate, whereas predictors included detailed demographic, socio-economic, geographic, seasonal and health/lifestyle data. The prevalence of deficient or low B12 status (45 nmol/l) was observed in 8·9 %, whereas high B12 status was observed in 3·1 % (>601 pmol/l). The largest positive predictor of B12 concentration was self-reported B12 injection and/or supplement use (coefficient 51·5 pmol/; 95 % CI 9·4, 93·6; P=0·016) followed by sex and geographic location. The largest negative predictor was metformin use (-33·6; 95 % CI -51·9, -15·4; P<0·0001). The largest positive predictor of folate concentration was folic acid supplement use (6·0; 95 % CI 3·0, 9·0 nmol/l; P<0·001) followed by being female and statin medications. The largest negative predictor was geographic location (-5·7; 95 % CI -6·7, -4·6; P<0·0001) followed by seasonality and smoking. B-vitamin status in older adults is affected by health and lifestyle, medication, sampling period and geographic location. We observed a high prevalence of low B12 and folate status, indicating that the current policy of voluntary fortification is ineffective for older adults.

Vitamin B12 status in kidney transplant recipients: association with dietary intake, body adiposity and immunosuppression

The aim of the present study was to evaluate the prevalence of vitamin B12 (B12) deficiency in kidney transplant recipients (KTR) and its possible association with B12 dietary intake, body adiposity and immunosuppressive drugs. In this cross-sectional study, we included 225 KTR, aged 47·50 (sd 12·11) years, and 125 (56 %) were men. Serum levels of B12 were determined by chemiluminescent microparticle intrinsic factor assay and the cut-off of 200 pg/ml was used to stratify KTR into B12-sufficient or B12-deficient group. B12 dietary intake was evaluated by three 24 h dietary recalls and was considered adequate when ≥2·4 μg/d. Body adiposity was estimated after taking anthropometric measures and using the dual-energy X-ray absorptiometry (DXA) method. B12 deficiency was seen in 14 % of the individuals. B12-deficient group, compared with the B12-sufficient group, exhibited lower intake of B12 (median 2·42 (interquartile range (IQR) 1·41-3·23) v. 3·16 (IQR 1·94-4·55) μg/d, P = 0·04) and higher values of waist circumference (median 96·0 (IQR 88·0-102·5) v. 90·0 (IQR 82·0-100·0) cm, P = 0·04). When the analysis included only women, B12 deficiency was associated with higher total and central body adiposity measurements obtained with anthropometry (BMI, body adiposity index, waist and neck circumferences) and DXA (total and trunk body fat). Among individuals with adequate intake of B12, the deficiency of this vitamin was more frequently seen in those using mycophenolate mofetil (MMF) (17 %) v. azathioprine (2 %), P = 0·01. In conclusion, the prevalence of B12 deficiency in KTR was estimated as 14 % and was associated with reduced intake of B12 as well as higher adiposity, especially in women, and with the use of MMF.

Age-specific reference ranges are needed to interpret serum methylmalonic acid concentrations in the US population

BACKGROUND

Serum vitamin B-12 is measured to evaluate vitamin B-12 status. Serum methylmalonic acid (MMA) is a specific functional indicator of vitamin B-12 status; however, concentrations increase with impaired renal function.

OBJECTIVE

The aim of this study was to describe the distribution of serum vitamin B-12 and MMA in US adults, and estimate age-specific reference intervals for serum MMA in a healthy subpopulation with replete vitamin B-12 status and normal renal function.

METHODS

We examined cross-sectional data for serum vitamin B-12 and MMA in adults participating in the NHANES from 2011 to 2014. Vitamin B-12 was measured by electrochemiluminescence assay and MMA by isotope-dilution liquid chromatography-tandem mass spectrometry.

RESULTS

In both bivariate and multivariate analyses, age, race/Hispanic origin, and vitamin B-12 supplement use were generally significantly associated with serum vitamin B-12 and MMA concentrations. Serum MMA concentrations increased with age, particularly in persons aged ≥70 y. Non-Hispanic white persons had lower vitamin B-12 and higher MMA concentrations than non-Hispanic black persons. Shorter fasting times and impaired renal function were significantly associated with higher serum MMA concentrations, but not with serum vitamin B-12 concentrations after controlling for covariates. The central 95% reference intervals for serum vitamin B-12 and MMA concentrations were widest for persons aged ≥70 y compared with younger age groups. Compared with the overall population, the central 95% reference intervals for serum MMA concentrations were considerably narrower for a vitamin B-12-replete subpopulation with normal renal function, but still age-dependent. Serum vitamin B-12 showed little, whereas serum MMA showed notable, increases with impaired renal function.

CONCLUSIONS

The higher serum MMA concentrations throughout the entire distribution in older persons (especially persons aged ≥70 y) who are vitamin B-12-replete and have normal renal function indicate the need for age-specific MMA reference intervals to better interpret vitamin B-12 status in epidemiologic research.

Neurological disorders in vitamin B12 deficiency

The review discusses thesteps of vitamin B12 metabolism and its role in maintaining of neurological functions. The term "vitamin B12 (cobalamin)" refers to several substances (cobalamins) of a very similar structure. Cobalamin enters the body with animal products. On the peripherу cobalamin circulates only in binding with proteins transcobalamin I and II (complex cobalamin-transcobalamin II is designated as "holotranscobalamin"). Holotranscobalamin is absorbed by different cells, whereas transcobalamin I-binded vitamin B12 - only by liver and kidneys. Two forms of cobalamin were identified as coenzymes of cellular reactions which are methylcobalamin (in cytoplasm) and hydroxyadenosylcobalamin (in mitochondria). The main causes of cobalamin deficiency are related to inadequate intake of animal products, autoimmune gastritis, pancreatic insufficiency, terminal ileum disease, syndrome of intestinal bacterial overgrowth. Relative deficiency may be seen in excessive binding of vitamin B12 to transcobalamin I. Cobalamin deficiency most significantly affects functions of blood, nervous system and inflammatory response. Anemia occurs in 13-15% of cases; macrocytosis is an early sign. The average size of neutrophils and monocytes is the most sensitive marker of megaloblastic hematopoiesis. The demands in vitamin B12 are particularly high in nervous tissue. Hypovitaminosis is accompanied by pathological lesions both in white and gray brain matter. Several types of neurological manifestations are described: subacute combined degeneration of spinal cord (funicular myelinosis), sensomotor polyneuropathy, optic nerve neuropathy, cognitive disorders. The whole range of neuropsychiatric disorders with vitamin B12 deficiency has not been studied well enough. Due to certain diagnostic difficulties they are often regarded as "cryptogenic", "reactive", "vascular» origin. Normal or decreased total plasma cobalamin level could not a reliable marker of vitamin deficiency. In difficult cases the content of holotranscobalamin, methylmalonic acid / homocysteine, and folate in the blood serum should be investigated besides carefully analysis of clinical manifestations.

Addressing optimal folate and related B-vitamin status through the lifecycle: health impacts and challenges

The functional effects of folate within C1 metabolism involve interrelationships with vitamin B12, vitamin B6 and riboflavin, and related gene–nutrient interactions. These B vitamins have important roles throughout life, from pregnancy, through childhood, to middle and older age. Achieving optimal nutritional status for preventing folate-related disease is challenging, however, primarily as a result of the poor stability and incomplete bioavailability of folate from natural food sources when compared with the synthetic vitamin form, folic acid. Thus, in European countries, measures to prevent neural tube defects (NTD) have been largely ineffective because of the generally poor compliance of women with folic acid supplementation as recommended before and in early pregnancy. In contrast, countries worldwide with mandatory folic acid fortification policies have experienced marked reductions in NTD. Low vitamin B12 status is associated with increased risk of cognitive dysfunction, CVD and osteoporosis. Achieving optimal B12 status can be problematic for older people, however, primarily owing to food-bound B12 malabsorption which leads to sub-clinical deficiency even with high dietary B12 intakes. Optimising B-vitamin intake may be particularly important for sub-populations with impaired folate metabolism owing to genetic characteristics, most notably the 677C→T variant in the gene encoding the enzyme methylenetetrahydrofolate reductase (MTHFR). This common folate polymorphism is linked with several adverse health outcomes, including stroke, however, recent evidence has identified its novel interaction with riboflavin (the MTHFR cofactor) in relation to blood pressure and risk of developing hypertension. This review addresses why and how the optimal status of folate-related B vitamins should be achieved through the lifecycle.

The Role of Vitamin B12 in the Management and Optimization of Treatment in Patients With Degenerative Cervical Myelopathy

STUDY DESIGN

Narrative review.

OBJECTIVES

To discuss the relationship between degenerative cervical myelopathy (DCM) and vitamin B12 deficiency. Specifically, it is the aim to outline the rational for future research into assessment and therapeutic optimization of vitamin B12 in the treatment of DCM.

METHODS

Literature review.

RESULTS

DCM is the commonest cause of spinal cord impairment, with an average age of presentation in the sixth decade. Patients at this age have also been reported to have a high prevalence of vitamin B12 deficiency, with estimates of up to 20% in the elderly. Vitamin B12 deficiency can result in subacute combined degeneration of the spinal cord (SACD), and several case reports have pointed to patients with both DCM and SACD. Both SACD and reversible compressive injury due to DCM necessitate remyelination in the spinal cord, a process that requires adequate vitamin B12 levels. Basic science research on nerve crush injuries have shown that vitamin B12 levels are altered after nerve injury and that vitamin B12 along with dexamethasone or nonsteroidal anti-inflammatory drugs can reduce Wallerian degeneration. Furthermore, it has been suggested that a combination of B-vitamins can reduce glutamate-induced neurotoxicity.

CONCLUSIONS

Given the high prevalence of clinical and subclinical vitamin B12 deficiency in the elderly, the role of vitamin B12 in myelination, and vitamin B12 deficiency as a differential diagnosis of DCM, it is important to investigate what role vitamin B12 levels play in patients with DCM in terms of baseline neurological function and whether optimization of vitamin B12 levels can improve surgical outcome. Furthermore, the routine assessment of vitamin B12 levels in patients considered for DCM surgery should be considered.

[Folic acid and vitamin B12 determination in the assessment of cognitive disorders : Overview and data analysis from a university outpatient memory clinic]

Vitamin B12 and folic acid deficiencies are particularly frequent conditions in older people. Since these metabolic disorders represent relevant dyscognitive factors, the assessment of vitamin B12 and folic acid levels is essential in the diagnostic approach of cognitive disorders, such as mild cognitive impairment and dementia in an outpatient memory clinic. This article summarizes the relevant diagnostic and therapeutic aspects of vitamin B12 and folic acid deficiencies and their effects on cognition. The literature review is supplemented by a data analysis of a naturalistic cohort of 250 patients from this outpatient memory clinic.

Methylmalonic Acid and Homocysteine as Indicators of Vitamin B12 Deficiency in Patients with Gastric Cancer after Gastrectomy

Vitamin B12 deficiency is a common complication in patients after gastrectomy. Elevated methylmalonic acid (MMA) and homocysteine are better indications of vitamin B12 deficiency than vitamin B12 serum level. We compared MMA and homocysteine levels of patients with gastric cancer after gastrectomy (n = 151) with controls (n = 142) and evaluated the prevalence of vitamin B12 deficiency using MMA and homocysteine in patients. MMA and homocysteine levels were significantly higher (p < 0.05) in patients with gastric cancer after gastrectomy. Of the 151 patients assessed after gastrectomy, 32 patients (21.2%) were vitamin B12 deficient as defined by serum MMA levels > 350 nmol/L, and 8 patients (5.3%) were vitamin B12 deficient as defined by serum homocysteine levels > 15 μmol/L. Both MMA and homocysteine levels were elevated in 7 patients. Among 33 patients with elevated MMA or homocysteine levels, 8 patients (24.2%) were vitamin B12 deficient based on a serum vitamin B12 level < 200 pg/mL. Additionally, levels of MMA and homocysteine were compared pre- and post-gastrectomy in 27 patients. The median MMA level was higher in patients with post-gastrectomy compared to pre-gastrectomy, while the median serum homocysteine level was not significantly different. These results indicate that using serum vitamin B12 levels alone may fail to detect vitamin B12 deficiency. Additional assessments of MMA and homocysteine levels are useful to evaluate possible vitamin B12 deficiency in patients who underwent a gastrectomy, and MMA is a better indicator than homocysteine to detect early changes in vitamin B12 levels.

Epigenetic Factors in Late-Onset Alzheimer's Disease: MTHFR and CTH Gene Polymorphisms, Metabolic Transsulfuration and Methylation Pathways, and B Vitamins

DNA methylation and other epigenetic factors are important in the pathogenesis of late-onset Alzheimer's disease (LOAD). Methylenetetrahydrofolate reductase (MTHFR) gene mutations occur in most elderly patients with memory loss. MTHFR is critical for production of S-adenosyl-l-methionine (SAM), the principal methyl donor. A common mutation (1364T/T) of the cystathionine-γ-lyase (CTH) gene affects the enzyme that converts cystathionine to cysteine in the transsulfuration pathway causing plasma elevation of total homocysteine (tHcy) or hyperhomocysteinemia-a strong and independent risk factor for cognitive loss and AD. Other causes of hyperhomocysteinemia include aging, nutritional factors, and deficiencies of B vitamins. We emphasize the importance of supplementing vitamin B12 (methylcobalamin), vitamin B₉ (folic acid), vitamin B₆ (pyridoxine), and SAM to patients in early stages of LOAD.

Vitamin B12 deficiency and clinical laboratory: Lessons revisited and clarified in seven questions

The objective of this review article is to address the most frequently asked questions that pathologists and primary care physicians might face when dealing with a patient with suspicion of vitamin B12 deficiency. More specifically, the article mainly discusses the importance and prevalence of the deficit, how to recognize it, and the important role of a prompt diagnosis confirmation based on laboratory biomarkers for efficient replacement therapy.

Selected B vitamins and their possible link to the aetiology of age-related sarcopenia: relevance of UK dietary recommendations

The possible roles of selected B vitamins in the development and progression of sarcopenia are reviewed. Age-related declines in muscle mass and function are associated with huge and increasing costs to healthcare providers. Falls and loss of mobility and independence due to declining muscle mass/function are associated with poor clinical outcomes and their prevention and management are attractive research targets. Nutritional status appears a key modifiable and affordable intervention. There is emerging evidence of sarcopenia being the result not only of diminished anabolic activity but also of declining neurological integrity in older age, which is emerging as an important aspect of the development of age-related decline in muscle mass/function. In this connection, several B vitamins can be viewed as not only cofactors in muscle synthetic processes, but also as neurotrophic agents with involvements in both bioenergetic and trophic pathways. The B vitamins thus selected are examined with respect to their relevance to multiple aspects of neuromuscular function and evidence is considered that requirements, intakes or absorption may be altered in the elderly. In addition, the evidence base for recommended intakes (UK recommended daily allowance) is examined with particular reference to original datasets and their relevance to older individuals. It is possible that inconsistencies in the literature with respect to the nutritional management of sarcopenia may, in part at least, be the result of compromised micronutrient status in some study participants. It is suggested that in order, for example, for intervention with amino acids to be successful, underlying micronutrient deficiencies must first be addressed/eliminated.

Identification of vitamin B12 deficiency in vegetarian Indians

The prevalence of a sub-clinical vitamin B12 deficiency in the vegetarians is high. Total serum vitamin B12 concentration alone does not reliably reflect vitamin B12 status. Holotranscobalamin (holo-TC) II is a bioactive B12 fraction promoting specific uptake of B12 by cells and the circulating concentration reflects the intake of B12, whereas total homocysteine (tHcy) indicates the metabolic ability. In this study, we investigated the diagnostic value of circulating holo-TC, B12, folate and homocysteine in vegetarians who were at risk of B12 deficiency. B12-related biomarkers were measured in 119 young, healthy graduate vegetarians. None was folate deficient. As per reported definition, half were B12 deficient; 70 % of males and 50 % of females had low plasma holo-TC concentrations; and 92 % of males and half of females had hyperhomocysteinaemia. None had any clinical signs of B12 deficiency. Receiver operating characteristic curve analysis demonstrated similar AUC at the B12 concentration of 100 and 150 pmol/l when holo-TC (0·777 and 0·784) and homocysteine (0·924 and 0·928) were used as variables. Cut-off value of 100 pmol/l resulted in the highest sensitivity of 77·78 % and specificity of 71·05 % with a predictive value of 19·6 pmol/l for holo-TC and a sensitivity of 82·72 % and specificity of 89·7 % with a predictive value of 21·7 µmol/l for homocysteine. The combination of B12, holo-TC and tHcy improves the diagnostic accuracy at these cut-offs, and we suggest that for the young Indian vegetarians the cut-off for plasma B12 and holotrancobalamin is 100 pmol/l and 19·6 pmol/l, respectively, and for homocysteine it is 17·6 (females) and 27 µmol/l (males) for identifying B12 deficiency.

Should vitamin B12 status be considered in assessing risk of neural tube defects?

There is a strong biological premise for including vitamin B₁₂ with folic acid in strategies to prevent neural tube defects (NTDs), due to the closely interlinked metabolism of these two vitamins. For example, reduction of B₁₂ deficiency among women of reproductive age could enhance the capacity of folic acid to prevent NTDs by optimizing the cellular uptake and utilization of natural folate cofactors. Vitamin B₁₂ might also have an independent role in NTD prevention, such that adding it in fortification programs might be more effective than fortifying with folic acid alone. Globally, there is ample evidence of widespread vitamin B₁₂ deficiency in low‐ and middle‐income countries, but there is also considerable divergence of vitamin B₁₂ status across regions, likely due to genetic as well as nutritional factors. Here, I consider the evidence that low vitamin B₁₂ status may be an independent factor associated with risk of NTDs, and whether a fortification strategy to improve B₁₂ status would help reduce the prevalence of NTDs. I seek to identify knowledge gaps in this respect and specify research goals that would address these gaps.

A missense mutation in TCN2 is associated with decreased risk for congenital heart defects and may increase cellular uptake of vitamin B12 via Megalin

Deregulation of folate and vitamin B12 (VB12) metabolism contributes to the risk of congenital heart defects (CHDs). Transcobalamin (TCN2) is essential for transporting VB12 from blood to cells as TCN2-bound VB12 (holo-TC) is the only form for somatic cellular uptake. In this study, we performed an association study between common polymorphisms in 46 one carbon metabolism genes and CHD in 412 CHDs and 213 controls. Only two significant association signals in coding regions were identified: FTCD c.1470C>T & TCN2 c.230A>T. The only missense mutation, TCN2 c.230A>T, was further validated in 412 CHDs and 1177 controls. TCN2 c.230T is significantly associated with reduced CHD risk in North Chinese (odds ratio = 0.67, P = 4.62e-05), compared with the 230A allele. Interestingly, the mean level of plasma holo-TC in women with the TA genotype was 1.77-fold higher than that in women with the AA genotype. Further analysis suggested that c.230A>T enhanced the cellular uptake of holo-TC via the LRP2 receptor. Our results determined that a functional polymorphism in TCN2 contributes to the prevalence of CHDs. TCN2 c.230A>T is significantly associated with a reduced CHD risk, likely due to TCN2 c.230T improving the interaction between holo-TC and its LRP2 receptor.

False low holotranscobalamin levels in a patient with a novel TCN2 mutation

BACKGROUND

Measurement of holotranscobalamin (holoTC) is increasingly used as a screening test for cobalamin (Cbl) deficiency. A level well below the reference interval strongly supports a deficient state. We examined a 21-year-old woman diagnosed as Cbl deficient because of an extremely low holoTC level as measured by the Abbott Architect Assay.

METHODS

The patient was evaluated for Cbl deficiency employing an in-house holoTC method as well as other routine markers of Cbl status. Further analyses included exploration of the Cbl binding proteins employing gel filtration of a serum sample saturated with 57 Co-labeled Cbl and Sanger sequencing of exons 1-9 and the intron-exon boundaries of the TCN2 gene, the gene coding for transcobalamin (TC).

RESULTS

The patient had normal hematological variables throughout. Despite initial treatment with Cbl, holoTC as measured by the Abbott assay remained low, while holoTC measured with the in-house assay was normal, and behaved as TC upon gel-filtration. By Sanger sequencing, we detected a homozygous single point mutation c.855T>A in exon 6 of TCN2, corresponding to a asparagine (Asn) to lysine (Lys) substitution in position 267 of the mature protein.

CONCLUSIONS

We describe a novel point mutation of the TCN2 gene. The mutation does not seem to interfere with the function of TC, but the mutation may well explain the low level of holoTC detected by the Abbott assay. Our results underscores that mutations of TCN2 have to be considered when implausible holoTC results are obtained.

Relationship Between the Levels of Holotranscobalamin and Vitamin B12 in Children

The purpose of this study was to evaluate the relationship between the plasma holoTC and serum vitamin B₁₂ in children and to identify a cutoff cobalamin values according to holoTC. One hundred and fifty-five children were enrolled into the study. All children were evaluated for hemoglobin, vitamin B₁₂, folate, ferritin and holoTC levels. Children were grouped as with low vitamin B₁₂ level (≤200 pg/mL, group I) and normal vitamin B₁₂ (>200 pg/mL, group II). Serum vitamin B₁₂, and holoTC levels were performed in each patient in the study. In 101 patients with low vitamin B₁₂ (group I) the mean holoTC was 21.74 ± 1.14 pmol/L. In 54 children with normal vitamin B₁₂ (group II) mean holoTC was 44.0 ± 2.7 pmol/L (p < 0.01). A ROC curve analysis was performed to delineate the optimum cut-off point for vitamin B₁₂ level and it was found to be 165 pg/mL with a sensitivity of 70% and specificity of 74%; the area under curve was 0.783 (p < 0.01). Our study displayed a positive correlation between vitamin B₁₂ and holoTC, and defined an optimum cutoff value for vitamin B₁₂ as 165 pg/mL. Further studies using the markers both MMA, tHcy and holoTC to confirm the findings are needed.

Vitamin B12 Intake and Related Biomarkers: Associations in a Dutch Elderly Population

BACKGROUND

Vitamin B12 status is measured by four plasma/ serum biomarkers: total vitamin B12 (total B12), holotranscobalamin (holoTC), methylmalonic acid (MMA) and homocysteine (tHcy). Associations of B12 intake with holoTC and tHcy and associations between all four biomarkers have not been extensively studied. A better insight in these associations may contribute to an improved differentiation between vitamin B12 deficiency and a normal vitamin B12 status.

OBJECTIVE

This study investigates associations between vitamin B12 intake and biomarkers and associations between biomarkers.

DESIGN

In this cross-sectional observational study, levels of total B12, HoloTC, MMA and tHcy were determined in participants of the B-PROOF study: 2919 elderly people (≥65 years, with a mean age of 74.1 years, a mean BMI of 27.1 and 50% women) with elevated tHcy levels (≥12 µmol/L). B12 intake was assessed in a subsample. We assessed the association between intake and status with multivariate regression analysis. We explored the dose-response association between B12 intake and biomarkers and the association of total B12 and holoTC with tHcy and MMA with restricted cubic spline plots.

RESULTS

A doubling of B12 intake was associated with 9% higher total B12, 15% higher HoloTC, 9% lower MMA and 2% lower tHcy. Saturation of biomarkers occurs with dietary intakes of >5 μg B12. Spline regression showed that levels of MMA and tHcy started to rise when vitamin B12 levels fall below 330 pmol/L and with HoloTC levels below 100 pmol/L, with a sharp increase with levels of B12 and HoloTC below 220 and 50 pmol/L respectively.

CONCLUSIONS

In this study we observed a significant association between vitamin B12 intake and vitamin B12 biomarkers and between the biomarkers. The observed inflections for total B12 and holoTC with MMA and tHcy could indicate cut-off levels for further testing for B12 deficiency and determining subclinical B12 deficiency.

Dairy Intakes in Older Irish Adults and Effects on Vitamin Micronutrient Status: Data from the TUDA Study

BACKGROUND

Consumption of dairy products has been associated with positive health outcomes including a lower risk of hypertension, improved bone health and a reduction in the risk of type 2 diabetes. The suggested dairy intake for health in older adults is three servings per day but recent analysis of the NHANES data for older adults reported 98% were not meeting these recommendations. No studies have investigated the consequences of such declines in the dairy intakes of Irish older adults and the subsequent effects on vitamin micronutrient status.

OBJECTIVES

To study the daily dairy intakes of older Irish adults and to examine how the frequency of dairy food consumption affects vitamin micronutrient status.

METHODS

Participants (n 4,317) were from the Trinity Ulster Department of Agriculture (TUDA) Study, a large study of older Irish adults (aged >60 yrs) designed to investigate gene-nutrient interactions in the development of chronic diseases of aging. The daily intake portion for milk, cheese and yoghurt was calculated from food frequency questionnaire (FFQ) responses. Blood samples were analysed for vitamin biomarkers as follows: vitamin B12 (total serum cobalamin and holotranscobalamin (holoTC)), folate (red cell folate (RCF) and serum folate), vitamin B2 (erythrocyte glutathione reductase activation coefficient (EGRac)), vitamin B6 (serum pyridoxal phosphate) and vitamin D (serum 25(OH)D).

RESULTS

The mean total reported dairy intake was 1.16 (SD 0.79) portions per day with males consuming significantly fewer total dairy portions compared to females (1.07 vs 1.21 respectively) (P<0.05). There was no significant difference in total daily dairy serving intakes by age decade (60-69, 70-79, >80 yrs). Overall, only 3.5% of the total population (n 151) achieved the recommended daily dairy intake of three or more servings per day. A significantly higher proportion of females (4%) compared to males (2.4%) met these dairy requirements (P=0.011). Blood concentrations of vitamin B12 biomarkers, RCF, vitamin B2 and vitamin B6 were significantly worse in those with the lowest tertile of dairy intake (0-0.71 servings) compared to those in the highest tertile (1.50-4.50 servings) (P<0.05).

CONCLUSION

This study found that more than 96% of the older adults sampled did not meet current daily dairy intake recommendations. The study is the largest to-date examining dairy intakes in older Irish adults, and provides evidence that daily dairy intakes (in particular yogurt) contribute significantly to the B-vitamin and vitamin D biomarker status of older adults. These results suggest that older adults who are already vulnerable to micronutrient inadequacies, are forgoing the nutritional advantages of vitamin-rich dairy products.

An International Standard for holotranscobalamin (holoTC): international collaborative study to assign a holoTC value to the International Standard for vitamin B12 and serum folate

BACKGROUND

Investigation of possible B12 and folate deficiencies requires measurement of these vitamins in serum. There is evidence that holotranscobalamin (holoTC), the active portion of B12 available to cells, is a more specific marker of early B12 deficiency than total B12. The availability of immunoassays for holoTC prompted an international collaborative study to assign a holoTC value to the World Health Organization (WHO) 1st International Standard (IS) for vitamin B12 and serum folate, 03/178.

METHODS

The IS, 03/178, and three serum samples with different holoTC levels were assayed by 12 laboratories in eight countries using manual and automated immunoassays for holoTC; one laboratory additionally performed an in-house assay. Fourteen sets of data were analysed.

RESULTS

Overall, the IS, 03/178, and the three serum samples demonstrated assay linearity and parallelism. An overall geometric mean (GM) holoTC value of 106.8 pmol/L was obtained for 03/178, with an inter-laboratory geometric coefficient of variation (GCV) of 10.5%. There was a reduction in inter-laboratory variability when the holoTC levels in the serum samples were determined relative to the IS with an assigned holoTC value rather than to the assays' calibration. Accelerated degradation studies showed that 03/178 was sufficiently stable to serve as an IS for holoTC.

CONCLUSIONS

The WHO Expert Committee on Biological Standardization endorsed the proposal to assign a holoTC value of 107 pmol/L to 03/178, corresponding to 0.107 pmol per ampoule, for use as the 1st IS for vitamin B12, serum folate, and holoTC.

Biomarkers and Algorithms for the Diagnosis of Vitamin B12 Deficiency

Vitamin B12 (cobalamin, Cbl, B12) is an indispensable water-soluble micronutrient that serves as a coenzyme for cytosolic methionine synthase (MS) and mitochondrial methylmalonyl-CoA mutase (MCM). Deficiency of Cbl, whether nutritional or due to inborn errors of Cbl metabolism, inactivate MS and MCM leading to the accumulation of homocysteine (Hcy) and methylmalonic acid (MMA), respectively. In conjunction with total B12 and its bioactive protein-bound form, holo-transcobalamin (holo-TC), Hcy, and MMA are the preferred serum biomarkers utilized to determine B12 status. Clinically, vitamin B12 deficiency leads to neurological deterioration and megaloblastic anemia, and, if left untreated, to death. Subclinical vitamin B12 deficiency (usually defined as a total serum B12 of <200 pmol/L) presents asymptomatically or with rather subtle generic symptoms that oftentimes are mistakenly ascribed to unrelated disorders. Numerous studies have now established that serum vitamin B12 has limited diagnostic value as a stand-alone marker. Low serum levels of vitamin B12 not always represent deficiency, and likewise, severe functional deficiency of the micronutrient has been documented in the presence of normal and even high levels of serum vitamin B12. This review discusses the usefulness and limitations of current biomarkers of B12 status in newborn screening, infant and adult diagnostics, the algorithms utilized to diagnose B12 deficiency and unusual findings of vitamin B12 status in various human disorders.

Holotranscobalamin (HoloTC, Active-B12) and Herbert's model for the development of vitamin B12 deficiency: a review and alternative hypothesis

The concentration of total vitamin B12 in serum is not a sufficiently sensitive or specific indicator for the reliable diagnosis of vitamin B12 deficiency. Victor Herbert proposed a model for the staged development of vitamin B12 deficiency, in which holotranscobalamin (HoloTC) is the first indicator of deficiency. Based on this model, a commercial immunoassay has been controversially promoted as a replacement for the total vitamin B12 test. HoloTC is cobalamin (vitamin B12) attached to the transport protein transcobalamin, in the serum, for delivery to cells for metabolism. Although there have been many published reports supporting the claims for HoloTC, the results of some studies were inconsistent with the claim of HoloTC as the most sensitive marker of vitamin B12 deficiency. This review examines the evidence for and against the use of HoloTC, and concludes that the HoloTC immunoassay cannot be used to measure vitamin B12 status any more reliably than total vitamin B12, or to predict the onset of a metabolic deficiency, because it is based on an erroneous hypothesis and a flawed model for the staged development of vitamin B12 deficiency. The author proposes an alternative model for the development of vitamin B12 deficiency.

A Common Polymorphism in HIBCH Influences Methylmalonic Acid Concentrations in Blood Independently of Cobalamin

Methylmalonic acid (MMA) is a by-product of propionic acid metabolism through the vitamin B12 (cobalamin)-dependent enzyme methylmalonyl CoA mutase. Elevated MMA concentrations are a hallmark of several inborn errors of metabolism and indicators of cobalamin deficiency in older persons. In a genome-wide analysis of 2,210 healthy young Irish adults (median age 22 years) we identified a strong association of plasma MMA with SNPs in 3-hydroxyisobutyryl-CoA hydrolase (HIBCH, p = 8.42 × 10(-89)) and acyl-CoA synthetase family member 3 (ACSF3, p = 3.48 × 10(-19)). These loci accounted for 12% of the variance in MMA concentration. The most strongly associated SNP (HIBCH rs291466; c:2T>C) causes a missense change of the initiator methionine codon (minor-allele frequency = 0.43) to threonine. Surprisingly, the resulting variant, p.Met1?, is associated with increased expression of HIBCH mRNA and encoded protein. These homozygotes had, on average, 46% higher MMA concentrations than methionine-encoding homozygotes in young adults with generally low MMA concentrations (0.17 [0.14-0.21] μmol/L; median [25(th)-75(th) quartile]). The association between MMA levels and HIBCH rs291466 was highly significant in a replication cohort of 1,481 older individuals (median age 79 years) with elevated plasma MMA concentrations (0.34 [0.24-0.51] μmol/L; p = 4.0 × 10(-26)). In a longitudinal study of 185 pregnant women and their newborns, the association of this SNP remained significant across the gestational trimesters and in newborns. HIBCH is unique to valine catabolism. Studies evaluating flux through the valine catabolic pathway in humans should account for these variants. Furthermore, this SNP could help resolve equivocal clinical tests where plasma MMA values have been used to diagnose cobalamin deficiency.

Association of a transcobalamin II genetic variant with falsely low results for the holotranscobalamin immunoassay

BACKGROUND

The clinical use of holotranscobalamin (holoTC) testing to evaluate vitamin B12 status has increased in recent years. We present two patients (African Caribbean and Indian heritage), in which the holoTC assay indicated severe B12 deficiency (< 5 pmol/L). Additional clinical tests revealed that these patients had normal levels of total vitamin B12 in blood and unremarkable levels of two other markers of vitamin B12 status, homocysteine and methylmalonic acid. We hypothesized that these patients carry a variant in the transcobalamin gene (TCN2) that influences the most widely commercially available holoTC test - Active-B12 (Axis-Shield Diagnostics Ltd).

DESIGN

Exon sequencing of the TCN2 gene was carried out. Protein characterization included total transcobalamin (TCN2) detection by Western blot, and holoTC by (57) Co-labelled B12 binding followed by size fractionation.

RESULTS

Exon sequencing of TCN2 revealed both patients were homozygous for the minor allele of rs35838082 (p.R215W). Western blot and chromatographic analyses revealed that the serum of these patients contains intact transcobalamin and that this variant-containing protein binds vitamin B12 . The variant is rare in Caucasians (minor allele frequency (MAF) < 0·01) but more common in South Asians (MAF ~ 0·02) and those of African origin (MAF ~ 0·25).

CONCLUSIONS

The impeded ability to detect normal levels of holoTC in these two patients may be due to this variant interfering with the detection of holoTC by one or both of the monoclonal antibodies currently employed in the Active-B12 test. Laboratories should be aware of this variant and use confirmatory tests when applicable.

A review of the cut-off points for the diagnosis of vitamin B12 deficiency in the general population

Vitamin B12 deficit is one of the most common vitamin deficiencies. However, there is no consensus on the cut-off points for vitamin B12 and its co-markers, such as folate, holotranscobalamin, methylmalonic acid and homocysteine. In order to establish the state of the art about cut-off points used to determine vitamin B12 deficiency in the last decades, the database MEDLINE was used for searching studies published in adults between December 1992 and May 2014 (69 articles), using search terms like 'vitamin B12', 'cobalamin', 'cut-off', 'deficiency' alone or in combinations. Broad ranges of cut-off points for vitamin B12 and its biomarkers were identified: vitamin B12 ranged between 100 pmol/L and 350 pmol/L, holotranscobalamin 20-50 pmol/L, methylmalonic acid 0.210-0.470 μmol/L, homocysteine 10-21.6 μmol/L, serum folate 3.7-15.9 nmol/L and red blood cell 124-397 nmol/L. For the majority of studies, the potential influence of age, analytical methods, gender and fortified food consumption was not taken in account when choosing cut-off values. This could explain the discrepancies between studies on vitamin B12 and folate deficiency prevalences. We conclude that there is inconsistency in the literature regarding vitamin B12 cut-offs. It would be necessary to establish different reference cut-offs according to age, considering the analytical methods used.