Plasma Methylmalonic Acid Research Articles

Imbalanced Folate and Vitamin B12 in the Third Trimester of Pregnancy and its Association with Birthweight and Child Growth up to 2 Years.

Folic acid supplementation during pregnancy may lead to an imbalance when vitamin B12 intake is low (folate trap) and may affect child's growth. The authors study the association between third trimester maternal intakes of folate and B12 and birthweight and postnatal growth of 2632 infants from the KOALA Birth Cohort Study. Plasma vitamin biomarkers are measured in 1219 women. Imbalanced total intakes (folate >430µg day-1 combined with B12 <5.5µg day-1 ) are not associated with birthweight [β adj (95% CI) = -14.87 (-68.87, 39.13)]compared with high intakes of both.Imbalanced intake is associated with a lower z score of weight at 1-2 years [β adj = -0.14 (-0.25, -0.03)].Having red blood cell folate >745nmol L-1 and plasma B12 <172pmol L-1 is not associated with birthweight [β adj = -7.10 (-97.90, 83.71) g].Maternal dietary B12 intake[β adj = -9.5 (-15.6, -3.3)] and plasma methylmalonic acid [β adj = 234 (43, 426)] are associated with birthweight. Low maternal dietary B12 intake and elevated methylmalonic acid rather than imbalanced vitamins are associated with higher birthweight, suggesting thatlow maternal B12 can predispose the infants for later obesity.

Plasma Methylmalonic Acid Concentration in Folic Acid–Supplemented Depressed Patients with Low or Marginal Vitamin B-12: A Randomized Trial

BackgroundIndividuals with low serum vitamin B-12 and high serum folate have higher plasma concentrations of methylmalonic acid (MMA). Whether folic acid (FA) causes an increase in MMA is not known. ObjectivesWe aimed to determine the impact of FA supplementation on plasma MMA concentration in people with low or marginal serum vitamin B-12. MethodsWe conducted a multicenter double-blind placebo-controlled randomized trial of oral FA (5 mg/d for 12 wk) in middle-aged patients treated with antidepressant medication participating in the FoLATED (Folate Augmentation of Treatment—Evaluation for Depression) trial. Participants defined as having “low” serum vitamin B-12 (vitamin B-12 ≥150 and <220 ng/L) or “marginal” serum vitamin B-12 (vitamin B-12 ≥ 220 and <280 ng/L) were included. The primary outcome of this substudy was MMA at week 12. A mixed-effects linear regression was fitted and reported using the adjusted mean difference (aMD). ResultsA total of 177 participants were included (85 randomly assigned to placebo and 92 to FA); the mean ± SD age was 46.2 ± 11.8 y, and 112 (63.3%) were female. The MMA analysis included 135 participants and the aMD was −0.01 (95% CI: −0.06, 0.04; P = 0.71). Serum folate was measured on 166 participants and increased in the supplementation group; the aMD was 21.6 μg/L (95% CI: 8.13, 25.02 μg/L; P < 0.001). A total of 117 participants were assessed for RBC folate, which also increased in the supplementation group; the aMD was 461 μg/L (95% CI: 387, 535 μg/L; P < 0.001). ConclusionsSupplementation of FA leads to an increase of serum and RBC folate, but does not change plasma MMA concentration in individuals with serum vitamin B-12 between 150 and 280 ng/L. We cannot exclude effects in older people or those with serum vitamin B-12 <150 ng/L. Previously reported associations may arise from effects of impaired vitamin B-12 status on folate metabolism.This trial was registered at www.isrctn.com as ISRCTN37558856.

Fewer US adults had low or transitional vitamin B12 status based on the novel combined indicator of vitamin B12 status compared with individual, conventional markers, NHANES 1999–2004

Elevated plasma methylmalonic acid (MMA) and/or total homocysteine (tHcy), as well as low serum vitamin B12 and/or holotranscobalamin (holoTC) are indicative of vitamin B12 deficiency. Combined indicators (cB12), which pool some or all 4 markers into an index, may be a more reliable diagnostic tool to overcome inconclusive diagnoses with individual markers. We aimed to describe different cB12 score combinations and estimate the prevalence of low or transitional vitamin B12 status compared with individual markers. Using cross-sectional data for B12, MMA, and tHcy in persons ≥20 y participating in NHANES 1999-2004 (n=12,335), we examined raw and covariate-adjusted regression models to assess determinants of 3cB12 (all 3 markers) and combinations of 2cB12 (2 markers). 3cB12 was significantly associated with B12 (Spearman r=0.75), MMA (r = -0.70), and tHcy (r = -0.59). The 3cB12 reference interval (2.5th to 97.5th percentile) was -0.538 to 1.60. In covariate-adjusted models, we found no association of 3cB12 with age; adult females and users of B12 supplements had higher, while adults with advanced chronic kidney disease had lower 3cB12 levels regardless of race-Hispanic origin group (self-reported). Only 2.7% of adults had low or transitional vitamin B12 status using the proposed cB12 cutoff of ≤-0.5, while the prevalence of low (or low-normal) status depended on the selected individual marker and its cutoff: 2.2% and 13% for B12<148 and 148-222 pmol/L, respectively; 6.0% for MMA exceeding an age-specific cutoff (250-320 nmol/L); and 8.4% for tHcy>13 µmol/L. The reference intervals for B12, MMA, and tHcy overlapped from the low (<-2.5) to the transitional (-2.5 to -0.5) and to the adequate (>-0.5) cB12 categories. Vitamin B12 deficiency may be overestimated among US adults when individual, conventional markers are used. When only 2 markers are available, the combination of B12 and MMA provides results comparable to 3cB12.

Oral administration of cyanocobalamin for functional vitamin В&lt;sub&gt;12&lt;/sub&gt; deficiency: efficacy and safety

The prevalence of vitamin В12deficiency is about 3—16% in the general population, while in older people, it ranges from 10 to 20%. An increase in the proportion of people on reduced-calorie diets, the widespread use of drugs that can result in vitamin В12deficiency, an increase in life expectancy, on the one hand, a variety of clinical manifestations and the lack of precise algorithms for laboratory diagnostics, on the other hand, suggest that the number of patients with vitamin В12deficiency is significantly higher. Vitamin В12can be absorbed by passive diffusion, regardless of intrinsic factor and other underlying causes of the deficiency. The presence of an additional route of absorption brings in new expectations for the oral administration of cyanocobalamin in therapeutic doses. Comparative clinical trials of the use of cyanocobalamin have shown that the oral route of administration is as effective as the parenteral. Considering the need for long-term, and in some cases — life-long, use of the drug, there is a need to develop dosage regimens for oral administration comparable in effectiveness to parenteral administration. The use of functional vitamin В12deficiency biomarkers, such as vitamin В12levels, cholotranscobalamin, methylmalonic acid, homocysteine, made it possible to establish that a daily dose of 1000 mkg is the most effective, which at the initial stage is as efficient as intramuscular administration. In some circumstances, maintenance therapy (intramuscularly at a dose of 1 mg/month) was more effective; thus, a differentiated approach scheme to determining the maintenance oral dose was proposed, depending on the result obtained at the initial stage of therapy. Comparative studies covering the entire spectrum from the recommended dietary allowance to the dose commonly used for cobalamin injections have shown that an oral daily dose of 1000 mcg of cyanocobalamin normalizes serum vitamin В12levels and causes an 80—90% decrease in plasma methylmalonic acid concentration from the assumed maximum value. The oral route of administration provides a higher patient treatment adherence.

ImmTOR nanoparticles enhance AAV transgene expression after initial and repeat dosing in a mouse model of methylmalonic acidemia

A major barrier to adeno-associated virus (AAV) gene therapy is the inability to re-dose patients due to formation of vector-induced neutralizing antibodies (Nabs). Tolerogenic nanoparticles encapsulating rapamycin (ImmTOR) provide long-term and specific suppression of adaptive immune responses, allowing for vector re-dosing. Moreover, co-administration of hepatotropic AAV vectors and ImmTOR leads to an increase of transgene expression even after the first dose. ImmTOR and AAV Anc80 encoding the methylmalonyl-coenzyme A (CoA) mutase (MMUT) combination was tested in a mouse model of methylmalonic acidemia, a disease caused by mutations in the MMUT gene. Repeated co-administration of Anc80 and ImmTOR was well tolerated and led to nearly complete inhibition of immunoglobulin (Ig)G antibodies to the Anc80 capsid. A more profound decrease of plasma levels of the key toxic metabolite, plasma methylmalonic acid (pMMA), and disease biomarker, fibroblast growth factor 21 (FGF21), was observed after treatment with the ImmTOR and Anc80-MMUT combination. In addition, there were higher numbers of viral genomes per cell (vg/cell) and increased transgene expression when ImmTOR was co-administered with Anc80-MMUT. These effects were dose-dependent, with the higher doses of ImmTOR providing higher vg/cell and mRNA levels, and an improved biomarker response. Combining of ImmTOR and AAV can not only block the IgG response against capsid, but it also appears to potentiate transduction and enhance therapeutic transgene expression in the mouse model.

The marker of cobalamin deficiency, plasma methylmalonic acid, may help identifying lysosomal iron trapping in patients. Its possible utility for heart failure

Iron deficiency is known to aggravate the prognosis of patients with heart failure. Iron has functions in the mitochondrial respiratory chain. In patients with reduced mitochondrial respiration, the mitochondrial ratio between the level of nicotinamide adenine dinucleotide and its reduced form decreases. Due to the mitochondrial-lysosomal interplay, decreased mitochondrial respiration also leads to inhibition of lysosomal hydrolysis. As a result, cobalamin and iron will be trapped in lysosomes. This will, even if iron and cobalamin have been consumed and absorbed in sufficient amounts, lead to their functional deficiencies.1 Functional iron deficiency can further impede mitochondrial respiration. Increased plasma levels of methylmalonic acid were shown to predict all-cause and cardiovascular mortality in the general population. Treatments targeting mitochondrial and lysosomal function may correct the functional deficiencies and improve prognosis in a subgroup of patients with heart failure, notably those with skeletal muscle wasting. Methylmalonic acid levels may be used for monitoring response to treatment, thereby identifying patients of the subgroup in which disease outcome may improve.

Maternal Vitamin B12 Status and Risk of Cleft Lip and Cleft Palate Birth Defects in Tamil Nadu State, India.

The causal role of maternal nutrition in orofacial clefts is uncertain. We tested hypotheses that low maternal vitamin B12 and low folate status are each associated with an increased risk of isolated cleft lip with or without cleft palate (CL±P) in a case-control study in Tamil Nadu state, India. Case-mothers of CL±P children (n = 47) and control-mothers of unaffected children (n = 50) were recruited an average of 1.4 years after birth of the index child and plasma vitamin B12, methylmalonic acid (MMA), total homocysteine (tHcy), and folate were measured at that time. Logistic regression analyses estimated associations between nutrient biomarkers and case-control status. Odds ratios (ORs) contrasting biomarker levels showed associations between case-mothers and low versus high plasma vitamin B12 (OR = 2.48, 95% CI, 1.02-6.01) and high versus low plasma MMA, an indicator of poor B12 status (OR = 3.65 95% CI, 1.21-11.05). Case-control status was not consistently associated with folate or tHcy levels. Low vitamin B12 status, when defined by a combination of both plasma vitamin B12 and MMA levels, had an even stronger association with case-mothers (OR = 6.54, 95% CI, 1.33-32.09). Mothers of CL±P children in southern India were 6.5 times more likely to have poor vitamin B12 status, defined by multiple biomarkers, compared to control-mothers. Further studies in populations with diverse nutritional backgrounds are required to determine whether poor maternal vitamin B12 or folate levels or their interactions are causally related to CL±P.

Age dependency of plasma vitamin B12 status markers in Dutch children and adolescents

BackgroundVitamin B12 deficiency in children may be associated with (severe) neurological manifestations, therefore recognition is important. Diagnosing vitamin B12 deficiency in children is challenging. This study aimed to investigate plasma methylmalonic acid, holotranscobalamin, and total cobalamin in children 0–18 years of age and to estimate age-dependent reference intervals.MethodsPlasma vitamin B12 markers were measured in collected plasma samples of 170 children 0–18 years visiting a local primary care laboratory. All had within-reference hemoglobin and MCV values. Pediatric plasma vitamin B12 biomarkers were measured and reference values were derived thereof.ResultsPlasma methylmalonic acid was higher in young children, in particular between 1 and 6 months of age; total cobalamin and holotranscobalamin were highest from 0.5 to 4 years and decreased till 10 years of age. Plasma holotranscobalamin was highly correlated with plasma total cobalamin; their ratio was independent of age. Plasma methylmalonic acid was slightly more related to total cobalamin than to holotranscobalamin. A large proportion of mainly young children would be misclassified when adult references are applied.ConclusionsPediatric reference values for cobalamin markers are necessary to allow for early recognition and monitoring of children suspect of (clinical) cobalamin deficiency.ImpactWe analyzed three plasma vitamin B12 status markers, i.e., total cobalamin, holotranscobalamin, and methylmalonic acid, in the plasma of 170 children 0–18 years of age and were able to derive reference intervals thereof. Recognition of vitamin B12 deficiency in children is important but challenging as pediatric reference intervals for plasma vitamin B12 status markers, particularly plasma holotranscobalamin, are not well described. We think that our results may help early recognition and monitoring of children suspect of (clinical) vitamin B12 deficiency.

Plasma 3-hydroxyisobutyrate (3-HIB) and methylmalonic acid (MMA) are markers of hepatic mitochondrial fatty acid oxidation in male Wistar rats

ObjectiveDiscovery of specific markers that reflect altered hepatic fatty acid oxidation could help to detect an individual's risk of fatty liver, type 2 diabetes and cardiovascular disease at an early stage. Lipid and protein metabolism are intimately linked, but our understanding of this crosstalk remains limited. MethodsIn male Wistar rats, we used synthetic fatty acid analogues (3-thia fatty acids) as a tool to induce hepatic fatty acid oxidation and mitochondrial biogenesis, to gain new insight into the link between fatty acid oxidation, amino acid metabolism and TCA cycle-related intermediate metabolites in liver and plasma. ResultsRats treated with 3-thia fatty acids had 3-fold higher hepatic, but not adipose and skeletal muscle, expression of the thioesterase 3-hydroxyisobutyryl-CoA hydrolase (Hibch), which controls the formation of 3-hydroxyisobutyrate (3-HIB) in the valine degradation pathway. Consequently, 3-thia fatty acid-stimulated hepatic fatty acid oxidation and ketogenesis was accompanied by decreased plasma 3-HIB and increased methylmalonic acid (MMA) concentrations further downstream in BCAA catabolism. The higher plasma MMA corresponded to higher MMA-CoA hydrolase activity and hepatic expression of GTP-specific succinyl-CoA synthase (Suclg2) and succinate dehydrogenase (Sdhb), and lower MMA-CoA mutase activity. Plasma 3-HIB correlated positively to plasma and hepatic concentrations of TAG, plasma total fatty acids, plasma NEFA and insulin/glucose ratio, while the reverse correlations were seen for MMA. ConclusionOur study provides new insight into TCA cycle-related metabolic changes associated with altered hepatic fatty acid flux, and identifies 3-HIB and MMA as novel circulating markers reflective of mitochondrial β-oxidation in male Wistar rats.

Folate, vitamin B-12, and cognitive function in the Boston Puerto Rican Health Study

There is evidence that low plasma vitamin B-12 and folate individually, as well as an imbalance of high folic acid and low vitamin B-12 status, may be associated with lower cognitive function. We examined dietary and plasma folate and vitamin B-12 status, and their interaction, in relation to cognitive function in a cohort of older Puerto Rican adults. The design is cross-sectional, with 1408 participants from the Boston Puerto Rican Health Study (mean±SD age: 57.1±7.9 y). Cognitive function was assessed with a comprehensive test battery and a global composite score was derived. Plasma folate, vitamin B-12, and methylmalonic acid (MMA) were assessed in fasting blood samples. After adjusting for covariates, high plasma folate and high plasma vitamin B-12 were each positively associated with global cognitive score (β: 0.063; 95% CI: -0.0008, 0.127; P=0.053 and β: 0.062; 95% CI: 0.009, 0.12; P=0.023, respectively, for logged values, and β: 0.002; 95% CI: 0.00005, 0.004; P-trend=0.044 and β: 0.00018; 95% CI: 0.00001, 0.0003; P-trend=0.036, respectively, across tertiles). Nine percent of participants had vitamin B-12 deficiency (plasma vitamin B-12<148 pmol/L or MMA>271 nmol/L), but none were folate deficient (plasma folate<4.53 nmol/L). Deficient compared with higher vitamin B-12 was significantly associated with lower cognitive score (β: -0.119; 95% CI: -0.208, -0.029; P=0.009). We could not examine the interaction for vitamin B-12 deficiency and high plasma folate, because there were too few individuals (<1% of the cohort) in this category to draw conclusions. Low plasma vitamin B-12 and low plasma folate were each associated with worse cognitive function in this population. Vitamin B-12 deficiency was prevalent and clearly associated with poorer cognitive function. More attention should be given to identification and treatment of vitamin B-12 deficiency in this population. Additional, larger studies are needed to examine the effect of vitamin B-12 deficiency in the presence of high exposure to folic acid.

Effects of vitamin B12 supplementation on neurodevelopment and growth in Nepalese Infants: A randomized controlled trial.

Vitamin B12 deficiency is common and affects cell division and differentiation, erythropoiesis, and the central nervous system. Several observational studies have demonstrated associations between biomarkers of vitamin B12 status with growth, neurodevelopment, and anemia. The objective of this study was to measure the effects of daily supplementation of vitamin B12 for 1 year on neurodevelopment, growth, and hemoglobin concentration in infants at risk of deficiency. This is a community-based, individually randomized, double-blind placebo-controlled trial conducted in low- to middle-income neighborhoods in Bhaktapur, Nepal. We enrolled 600 marginally stunted, 6- to 11-month-old infants between April 2015 and February 2017. Children were randomized in a 1:1 ratio to 2 μg of vitamin B12, corresponding to approximately 2 to 3 recommended daily allowances (RDAs) or a placebo daily for 12 months. Both groups were also given 15 other vitamins and minerals at around 1 RDA. The primary outcomes were neurodevelopment measured by the Bayley Scales of Infant and Toddler Development 3rd ed. (Bayley-III), attained growth, and hemoglobin concentration. Secondary outcomes included the metabolic response measured by plasma total homocysteine (tHcy) and methylmalonic acid (MMA). A total of 16 children (2.7%) in the vitamin B12 group and 10 children (1.7%) in the placebo group were lost to follow-up. Of note, 94% of the scheduled daily doses of vitamin B12 or placebo were reported to have been consumed (in part or completely). In this study, we observed that there were no effects of the intervention on the Bayley-III scores, growth, or hemoglobin concentration. Children in both groups grew on an average 12.5 cm (SD: 1.8), and the mean difference was 0.20 cm (95% confidence interval (CI): -0.23 to 0.63, P = 0.354). Furthermore, at the end of the study, the mean difference in hemoglobin concentration was 0.02 g/dL (95% CI: -1.33 to 1.37, P = 0.978), and the difference in the cognitive scaled scores was 0.16 (95% CI: -0.54 to 0.87, P = 0.648). The tHcy and MMA concentrations were 23% (95% CI: 17 to 30, P < 0.001) and 30% (95% CI: 15 to 46, P < 0.001) higher in the placebo group than in the vitamin B12 group, respectively. We observed 43 adverse events in 36 children, and these events were not associated with the intervention. In addition, 20 in the vitamin B12 group and 16 in the placebo group were hospitalized during the supplementation period. Important limitations of the study are that the strict inclusion criteria could limit the external validity and that the period of vitamin B12 supplementation might not have covered a critical window for infant growth or brain development. In this study, we observed that vitamin B12 supplementation in young children at risk of vitamin B12 deficiency resulted in an improved metabolic response but did not affect neurodevelopment, growth, or hemoglobin concentration. Our results do not support widespread vitamin B12 supplementation in marginalized infants from low-income countries. ClinicalTrials.gov NCT02272842 Universal Trial Number: U1111-1161-5187 (September 8, 2014) Trial Protocol: Original trial protocol: PMID: 28431557 (reference [18]; study protocols and plan of analysis included as Supporting information).

Plasma methylcitric acid and its correlations with other disease biomarkers: The impact in the follow up of patients with propionic and methylmalonic acidemia.

Methylcitric acid (MCA) analysis has been mainly utilized for the diagnosis of propionate disorders or as a second-tier test in newborn screening, but its utility for patients monitoring still needs to be established. We explored the potential contribution of MCA in the long-term management of organic acidurias. We prospectively evaluated plasma MCA and its relationship with disease biomarkers, clinical status, and disease burden in 22 patients, 13 with propionic acidemia (PA) and nine with methylmalonic acidemia (MMA) on standard treatment and/or after transplantation. Samples were collected at scheduled routine controls or during episodes of metabolic decompensation (MD), 10 patients were evaluated after transplantation (six liver, two combined liver and kidney, 2 kidney). MCA levels were higher in PA compared to MMA and its levels were not influenced by the clinical status (MD vs well state). In MMA, MCA was higher in elder patients and, along with fibroblast growth factor 21 (FGF21) and plasma methylmalonic acid, negatively correlated with GFR. In both diseases, MCA correlated with ammonia, glycine, lysine, C3, and the C3/C2, C3/C16 ratios. The disease burden showed a direct correlation with MCA and FGF21, for both diseases. All transplanted patients showed a significant reduction of MCA in comparison to baseline values, with some differences dependent on the type of transplantation. Our study provided new insights in understanding the disease pathophysiology, showing similarities between MCA and FGF21 in predicting disease burden, long-term complications and in evaluating the impact of organ transplantation.

Diagnostic Performances of Urinary Methylmalonic Acid/Creatinine Ratio in Vitamin B12 Deficiency.

Sole measurement of plasma vitamin B12 is no longer enough to identify vitamin B12 (B12) deficiency. When plasma vitamin B12 is in the low-normal range, especially between 201 and 350 ng/L, B12 deficiency should be assessed by measurements of plasma homocysteine and/or plasma methylmalonic acid (MMA). However, these biomarkers also accumulate during renal impairment, leading to a decreased specificity for B12 deficiency. In such cases, urinary methylmalonic acid/creatinine ratio (uMMA/C) could be of interest, due to the stable urinary excretion of MMA. The objectives were to evaluate the influence of renal impairment on uMMA/C compared to plasma homocysteine and plasma methylmalonic acid, and to determine the diagnostic performances of uMMA/C in the diagnosis of B12 deficiency. We prospectively studied 127 patients with a plasma B12 between 201 and 350 ng/L. We noticed that uMMA/C was not dependent on renal function (p = 0.34), contrary to plasma homocysteine and plasma methylmalonic acid. uMMA/C showed a perspective diagnostic performance (AUC 0.71 [95% CI: 0.62–0.80]) and the threshold of 1.45 umol/mmol presented a high degree of specificity (87.9% [95% CI: 72.0–98.9]). In conclusion, uMMA/C is a promising biomarker to assess vitamin B12 status in doubtful cases, notably during renal impairment.

Elevated Plasma Vitamin B12 in Patients with Hepatic Glycogen Storage Diseases.

Background: Hepatic glycogen storage diseases (GSDs) are inborn errors of metabolism affecting the synthesis or breakdown of glycogen in the liver. This study, for the first time, systematically assessed vitamin B12 status in a large cohort of hepatic GSD patients. Methods: Plasma vitamin B12, total plasma homocysteine (tHcy) and methylmalonic acid concentrations were measured in 44 patients with hepatic GSDs and compared to 42 healthy age- and gender-matched controls. Correlations of vitamin B12 status with different disease markers of GSDs (including liver transaminase activities and triglycerides) as well as the vitamin B12 intake were studied. Results: GSD patients had significantly higher plasma vitamin B12 concentrations than healthy controls (p = 0.0002). Plasma vitamin B12 concentration remained elevated in GSD patients irrespective of vitamin B12 intake. Plasma vitamin B12 concentrations correlated negatively with triglyceride levels, whereas no correlations were detected with liver transaminase activities (GOT and GPT) in GSD patients. Merging biomarker data of healthy controls and GSD patients showed a positive correlation between vitamin B12 status and liver function, which suggests complex biomarker associations. A combined analysis of biomarkers permitted a reliable clustering of healthy controls versus GSD patients. Conclusions: Elevated plasma concentration of vitamin B12 (irrespective of B12 intake) is a common finding in patients with hepatic GSD. The negative correlation of plasma vitamin B12 with triglyceride levels suggests an influence of metabolic control on the vitamin B12 status of GSD patients. Elevated vitamin B12 was not correlated with GOT and GPT in our cohort of GSD patients. Merging of data from healthy controls and GSD patients yielded positive correlations between these biomarkers. This apparent dichotomy highlights the intrinsic complexity of biomarker associations and argues against generalizations of liver disease and elevated vitamin B12 in blood. Further studies are needed to determine whether the identified associations are causal or coincidental, and the possible impact of chronically elevated vitamin B12 on GSD.

Assessment of Vitamin B12 Deficiency and Risk Factors in Healthy Infants.

To study vitamin B12 deficiency in apparently healthy infants and their mothers and assess the risk factors. A hospital-based, cross-sectional, observational study was conducted from July 2016 through December 2017. Consecutive healthy and normally developing infants were enrolled. Red blood cell folate, plasma vitamin B12, homocysteine and methylmalonic acid levels of mothers and infants were assessed. Seventy-four healthy infants were enrolled. Male-to-female ratio was 1.5:1. Anemia in 66.2% (n = 49), low plasma B12 in 17.6% (n = 13), hyperhomocysteinemia in 48.6% (n = 36), plasma methylmalonic acid in 100% (n = 74) and 'confirmed' B12 deficiency in 38% (n = 28) infants were noted. The proportion of hyperhomocysteinemia increased to 75.7% (n = 56) infants using a lower cut-off of >10μmol/L. In mothers, low B12 in 19%, hyperhomocysteinemia in 57% and elevated plasma methylmalonic acid in 100% were noted. Median plasma B12 level was 314pg/ml (IQR 221-421), median plasma homocysteine 15.4μmol/L (IQR 11.3-21.7) and median plasma methylmalonic acid was 8.28μmol/L (IQR 4.4-13.1) in mothers. Folate deficiency was noted in 9.4% infants and 12% of mothers. Overall, 63.5% mothers were vegetarian and, 64% of the mothers of infants with confirmed vitamin B12 deficiency were pure vegetarians. Odds of developing vitamin B12 deficiency increased by more than 5 times in those whose mothers' serum vitamin B12 levels were low as compared to normal maternal vitamin B12 levels (OR 5.42; 95% CI:1.96-16.6; p 0.002). There is a high prevalence of vitamin B12 deficiency in infants and their mothers. There is urgent need to supplement our population with vitamin B12.

Functional vitamin B12 deficiency in phenylketonuria patients and healthy controls: An evaluation with combined indicator of vitamin B12 status as a biochemical index.

Vitamin B12 deficiency frequently appears in phenylketonuria patients having a diet poor in natural protein. The aims of this study were to evaluate vitamin B12 status in phenylketonuria patients by using combined indicator of vitamin B12 status (cB12) as well as methylmalonic acid and homocysteine, more specific and sensitive markers, in comparison with healthy controls. Fifty-three children and adolescents with phenylketonuria under dietary treatment and 30 healthy controls were assessed cross-sectionally. Serum vitamin B12 and folate concentrations were analysed by chemiluminescence immunoassay. Plasma methylmalonic acid and total homocysteine concentrations were measured by liquid chromatography-tandem mass spectrometry and liquid chromatography, respectively. cB12 was calculated by using a formula involving blood parameters. Methylmalonic acid and folate concentrations in phenylketonuria group were higher compared with controls. Methylmalonic acid concentrations were high in 56.5% of the patients and 26.7% of the controls with normal vitamin B12 concentrations. Based on cB12, a significant difference within the normal values was detected between the groups. However, although 24.5% of phenylketonuria patients and 13.3% of controls had decreased vitamin B12 status according to cB12, there was no significant difference. Children and adolescents with phenylketonuria having a strict diet can be at risk of functional vitamin B12 deficiency. This deficiency can be accurately determined by measuring methylmalonic acid concentrations. Calculation of cB12 as a biochemical index did not provide additional information compared with the measurement of methylmalonic acid alone, but may be helpful for classification of some patients with increased methylmalonic acid as having adequate vitamin B12 status.

Dietary Intake and Biomarkers of Folate and Cobalamin Status in Norwegian Preschool Children: The FINS-KIDS Study

ABSTRACTBackgroundFolate and cobalamin (vitamin B-12) are essential for growth and development. However, few population-based studies have investigated B-vitamin status in children.ObjectivesThis study aimed to assess biomarkers of folate and vitamin B-12 status and to explore their dietary determinants in healthy Norwegian children.MethodsUsing baseline data obtained from a randomized controlled trial on the effect of fish intake on neurodevelopment in children aged 4–6 y, we measured the plasma concentrations of folate, cobalamin, total plasma homocysteine (tHcy), and methylmalonic acid (MMA). Food-frequency questionnaires (FFQs) were used to assess dietary intake. We used unadjusted and multiple linear regression models to explore the determinants of biomarker concentrations.ResultsThe median (IQR) of plasma folate (n = 197) and plasma cobalamin (n = 195) concentrations were 15.2 (12.2–21.1) nmol/L and 785 (632–905) pmol/L, respectively. Plasma folate concentrations of <10 nmol/L were observed in 13% of the children. No child had a cobalamin concentration <148 pmol/L. Two children were identified with elevated plasma MMA concentrations (>0.26 μmol/L) and 8 children had elevated tHcy concentrations (>6.5 μmol/L). Plasma folate concentration was inversely correlated with tHcy (ρ = −0.24, P < 0.001); we found no correlation between tHcy and cobalamin (ρ = −0.075, P = 0.30). Children who consumed vitamin supplements had 51% higher plasma folate concentrations (P < 0.0001) than those who did not. Consumption of red meat for dinner more than twice a week was associated with 23% lower plasma folate (P < 0.01). No other significant associations between dietary intake and the biomarkers were observed.ConclusionsThe Norwegian preschool children from this cohort had adequate vitamin B-12 status. Poor folate status was common and associated with elevated tHcy. The implications of poor folate status during childhood should be a prioritized research question. This trial was registered at ClinicalTrials.gov as NCT02331667.

Role of Functional Biomarkers to Identify Early Vitamin B12 Deficiency in Patients with Sleeve Gastrectomy: A Cross-Sectional Study.

Background and objectives: Although laparoscopic sleeve gastrectomy (LSG) is effective for obesity management, postoperative vitamin B12 (B12) deficiency is of major concern. In this cross-sectional study, we assessed the levels of B12 and its related functional biomarkers, namely, total homocysteine (tHcy), methylmalonic acid (MMA), folate, methylcitric acid (MCA), and hemoglobin (Hb), in one-year postoperative LSG patients and matched controls. Materials and Methods: Plasma B12, tHcy, MMA, folate, and MCA were measured in matched controls (n = 66) and patients (n = 71) using validated liquid chromatography-tandem mass spectrometry techniques and protocols in the United Arab Emirates (UAE). Results: The median B12 concentration in patients (177 pmol/L) was significantly lower (p < 0.001) than in the controls (334.7 pmol/L). The tHcy and MMA levels were significantly increased (p < 0.001 and p = 0.011, respectively) and folate levels were significantly decreased (p = 0.001) in the LSG patients compared to the controls. Interestingly, no significant difference in MCA levels were observed between the two groups. The levels of tHcy and MMA were concomitantly increased with the decreased folate levels in postoperative LSG patients when compared with the controls. The Hb levels were significantly lower in males and females in the patient group compared with those in the control group, respectively (p = 0.005 and p = 0.043). Conclusions: This is the first report of serum levels of B12 and its functional biomarkers in postoperative LSG patients among a local population from the UAE. Our findings revealed significant alterations of the B12 biomarkers, total B12, MMA, and tHcy in one-year postoperative LSG patients.

Associations of Circulating Methylmalonic Acid and Vitamin B-12 Biomarkers Are Modified by Vegan Dietary Pattern in Adult and Elderly Participants of the Adventist Health Study 2 Calibration Study.

ABSTRACTBackgroundElevated plasma methylmalonic acid (MMA) is a functional biomarker of vitamin B-12 status but limited information is available on its prevalence in US vegetarians.ObjectivesThe study examines the prevalence of plasma MMA ≥0.27 µmol/L in those consuming vegetarian diets, its associations with vitamin B-12 intake and biomarkers, and the modifying effect of vegetarian patterns on these associations.MethodsIn this cross-sectional study (n = 785), concentrations of MMA, vitamin B-12, holotranscobalamin (holoTC), and homocysteine (Hcy) were determined in participants of the calibration substudy of the Adventist Health Study 2 (AHS-2). Vitamin B-12 intake from food, fortified food, and supplements was assessed by six 24-h recalls. Regression models were used to estimate ORs of having high MMA as related to vitamin B-12 status biomarkers, vitamin B-12 intake, and dietary pattern.ResultsThe prevalence of low vitamin B-12 status defined by serum vitamin B-12 <148 pmol/L, holoTC <35 pmol/L, MMA ≥0.27 and ≥0.37 μmol/L, or Hcy ≥15 μmol/L, and the OR of having high MMA did not differ by dietary pattern, possibly due to intake from fortified food and supplements. Total daily vitamin B-12 intake in the second tertile range of 4.4–14.5 μg/d reduced the likelihood of elevated MMA by 69%; and a doubling of vitamin B-12 intake was associated with a 4.3% decrease in plasma MMA. The association between log plasma MMA and biomarkers was modified by diet, with the vegan pattern showing an ∼3-fold stronger association with log serum vitamin B-12 and Hcy than did the nonvegetarian pattern.ConclusionsThe prevalence of vitamin B-12 intake <2.0 μg/d was 15.2% in vegans, 10.6% in lacto-ovo-vegetarians, and 6.5% in nonvegetarians. Given the irreversible neurological consequences of vitamin B-12 inadequacy, the importance of regular supplemental vitamin B-12 intake in adult and elderly individuals is stressed.

Impact of food-bound malabsorption on vitamin B12 status in older adults from the TUDA Ageing Cohort Study: preliminary findings

AbstractVitamin B12 deficiency is common among older adults, even with dietary intakes well in excess of current recommendations. Severe clinical B12 deficiency (i.e. pernicious anaemia) leads to irreversible neurological damage, but once diagnosed, can be treated effectively with B12 injections. A much more common cause of low vitamin B12 status in older adults is food-bound malabsorption owing to atrophic gastritis. This in turn leads to reduced gastric acid secretion, thus limiting B12 absorption from food (given the essential role of gastric acid in releasing B12 from food proteins). Proton pump inhibitor (PPI) drugs reduce gastric acid secretion, similar to atrophic gastritis, thus there is a concern that these medications may lead to vitamin B12 malabsorption. Therefore, the aim of this study was to investigate biomarker status of vitamin B12 in relation to atrophic gastritis and PPI usage. Data were accessed from The Trinity Ulster Department of Agriculture (TUDA) Ageing Cohort Study, a cross-sectional study of community-dwelling adults (n 5186, ≥ 60 years) recruited across Northern Ireland and the Republic of Ireland (2008–2012). TUDA participants were classified into 3 groups; ‘healthy’ controls, atrophic gastritis and PPI users. Vitamin B12 status was assessed using a total of four biomarkers: serum total B12; serum holotranscobalamin, holoTC; plasma methylmalonic acid, MMA; plasma homocysteine. Atrophic gastritis was identified using pepsinogen analysis (via ELISA), with a pepsinogen I : II ratio of &lt; 3 considered indicative of atrophic gastritis. Based on results from all four biomarkers, participants with atrophic gastritis were found to have significantly lower B12 status compared to healthy controls: e.g. mean (95% CI) serum total vitamin B12, 188 (156, 218) pmol/L vs. 262 (252, 272) pmol/L P &lt; 0.001; holoTC, 46.0 (38.1, 53.8) pmol/L vs. 60.3 (57.8, 62.8) pmol/L P &lt; 0.001; plasma MMA, 0.65 (0.52, 0.78) μmol/L vs. 0.37 (0.32, 0.42) μmol/L P = 0.001. No differences in B12 biomarker concentrations were observed between PPI users and healthy controls. Regular consumption of fortified foods (i.e. ≥ 5 portions per week) compared to non-regular consumption (i.e. 0–4 portions per week) impacted positively on B12 biomarker status in all participants. This effect however appeared insufficient to restore normal vitamin B12 status in those with atrophic gastritis. These results show that older adults with atrophic gastritis have significantly lower vitamin B12 biomarker status, particularly in those who did not regularly consume fortified foods. Further investigations of the effect of atrophic gastritis and PPI usage on B12 status are warranted.