Early pregnancy folate-cobalamin interactions and their effects on cobalamin status and hematologic variables throughout pregnancy

Folate and cobalamin status, indicators, modulators, interactions, and reference ranges from early pregnancy until birth: the Reus-Tarragona birth cohort study

BACKGROUND

Folate and cobalamin status, although essential for pregnancy, are not routinely monitored in prenatal care.

OBJECTIVES

To investigate folate and cobalamin status and determinants throughout pregnancy, in the absence of mandatory folic acid (FA) fortification.

METHODS

In a cohort study of 831 mothers recruited at <12 gestational weeks (GW), plasma folate, total homocysteine (tHcy), cobalamin, holotranscobalamin (holoTC), methylmalonic acid (MMA), red blood cell folate (RBCF), and the combined cobalamin status indicator (cB12) were determined at ≤12, 15, 24-27, 34 GW, labor and in the cord. Single nucleotide polymorphisms affecting folate and cobalamin status were determined. FA, cobalamin, micronutrient supplement use, and dietary folate and cobalamin intake (food frequency questionnaire) were recorded. Folate and cobalamin status predictors were assessed by multiple linear regression analysis.

RESULTS

Only 36.1% of the participants took FA preconceptionally and 47.4% and 7.3% had suboptimal RBCF (<906 nmol/L) and plasma cobalamin status (≤221 pmol/L), respectively, at ≤12 GW. RBCF determinants included planned pregnancy, FA supplementation, plasma cobalamin, and methylenetetrahydrofolate (MTHFR) 677C>T genotype. Cobalamin supplementation was positively associated with plasma cobalamin and early holoTC. Smoking and BMI were inversely associated with plasma cobalamin and early holoTC, but none were associated with MMA. Only participants with the MTHFR 677TT genotype, exceeding FA supplement recommendations, improved their folate status (interaction term: B (95% CI):0.15 (0.01, 0.29), P = 0.032). Smoking was inversely associated with plasma cobalamin status in participants with the methionine synthase reductase (MTRR) 524CC genotype only (interaction term:0.07 (0.01, 0.04), P = 0.014). Mothers with low early pregnancy cobalamin status and also those with bigger newborns, had lower cobalamin status at labor.

CONCLUSIONS

Suboptimal early pregnancy folate or cobalamin status affected 47.4% and 7.3% of the participants, respectively. The MTHFR 677TT genotype predicted folate status throughout pregnancy. Smoking and BMI were negatively associated with cobalamin status throughout pregnancy. Clinical Trial Registry number and website where it was obtained: NCT01778205. www.

CLINICALTRIALS

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Indicators of Cobalamin Status During Pregnancy, Pregnancy Outcome and Long-Term Effects on Offspring Health

BACKGROUND

Little attention has been given to prenatal cobalamin insufficiency in settings where dietary cobalamin intake is presumed adequate, such as populations with habitual intake of foods from animal sources.

RESULTS

However, low cobalamin status in women of fertile age has been reported in Europe, United States, and Canada. In India, where cobalamin deficiency is highly prevalent, it has been associated with an increased risk of miscarriage, intrauterine growth retardation, as well as insulin resistance and lower neurodevelopment scores in the offspring. Low cobalamin status in pregnancy has been associated with similar outcomes as those reported in the Indian studies although the evidence is scant and conflicting.

CONCLUSIONS

Consideration should be given to maternal cobalamin status in the context of prevention of adverse pregnancy outcomes as well as cobalamin insufficiency both in the mother and the offspring during lactation. Further attention is now justified with the increasing tendency toward plant-based diets. Reference intervals for cobalamin status during each trimester of pregnancy are needed and further investigation of the long-term conse-quences of low cobalamin status during pregnancy for health and development in the offspring is warranted.

Assessing mean corpuscular volume as a screening tool for gestational vitamin B12 deficiency based on NHANES

Vitamin B12 can lead to neurological deficits. We assessed whether the mean corpuscular volume (MCV) could be a sufficiently sensitive measurement for abnormal serum methylmalonic Acid (MMA) and total plasma homocysteine (tHCY) (biomarkers of vitamin B12 or folate deficiency) and if so, at what cutoff value. A total of 26,397 participants (12,730 males and 13,667 females) were included in the analysis. Weighted analysis was performed using NHANES data to calculate crude/adjusted associations between MCV-MMA/tHCY, using linear regression. Unadjusted odds ratios (OR) 95% CIs were estimated from logistic regression models. Receiver Operating Curve and the Youden Index were used to identify the MCV level that most accurately distinguished those with abnormal MMA and tHCY (dependent variables) from those without. A positive and significant correlation between MCV-MMA/tHCY was found in the general population between ages 18-85, 0.95 (95% C.I. 0.75-1.17) and 2.61 (95% C.I. 2.15-3.08). In pregnant women, for every unit increase in MCV there was a 19% increase in odds of abnormal MMA, OR 1.19 (95% C.I. 1.08-1.31), p=0.001 and the Area Under the Curve for MCV as a test for abnormal MMA was 78%. An MCV cutoff of 93.1 correctly identified abnormal MMA in pregnant women with 81% sensitivity and 77% specificity. In the general population the MCV test performed poorly in identifying abnormal MMA/tHCY. MCV is an inexpensive measurement that may be useful to screen asymptomatic pregnant women for vitamin B12 abnormalities. This may have a significant impact on reducing adverse neurological outcomes in their children.

Choline - a scoping review for Nordic Nutrition Recommendations 2023

Choline is an essential nutrient with metabolic roles as a methyl donor in one carbon metabolism and as a precursor for membrane phospholipids and the neurotransmitter acetylcholine. Choline content is particularly high in liver, eggs, and wheat germ, although it is present in a variety of foods. The main dietary sources of choline in the Nordic and Baltic countries are meat, dairy, eggs, and grain. A diet that is devoid of choline causes liver and muscle dysfunction within 3 weeks. Choline requirements are higher during pregnancy and lactation than in non-pregnant women. Although no randomized controlled trials are available, observational studies in human, supported by coherence from interventional studies with neurodevelopmental outcomes and experimental studies in animals, strongly suggest that sufficient intake of choline during pregnancy is necessary for normal brain development and function in the child. Observational studies suggested that adequate intake of choline could have positive effects on cognitive function in older people. However, prospective data are lacking, and no intervention studies are available in the elderly.

Epigenetic effects of folate and related B vitamins on brain health throughout life: Scientific substantiation and translation of the evidence for health improvement strategies

Suboptimal status of folate and/or interrelated B vitamins (B12 , B6 and riboflavin) can perturb one-carbon metabolism and adversely affect brain development in early life and brain function in later life. Human studies show that maternal folate status during pregnancy is associated with cognitive development in the child, whilst optimal B vitamin status may help to prevent cognitive dysfunction in later life. The biological mechanisms explaining these relationships are not clear but may involve folate-related DNA methylation of epigenetically controlled genes related to brain development and function. A better understanding of the mechanisms linking these B vitamins and the epigenome with brain health at critical stages of the lifecycle is necessary to support evidence-based health improvement strategies. The EpiBrain project, a transnational collaboration involving partners in the United Kingdom, Canada and Spain, is investigating the nutrition-epigenome-brain relationship, particularly focussing on folate-related epigenetic effects in relation to brain health outcomes. We are conducting new epigenetics analysis on bio-banked samples from existing well-characterised cohorts and randomised trials conducted in pregnancy and later life. Dietary, nutrient biomarker and epigenetic data will be linked with brain outcomes in children and older adults. In addition, we will investigate the nutrition-epigenome-brain relationship in B vitamin intervention trial participants using magnetoencephalography, a state-of-the-art neuroimaging modality to assess neuronal functioning. The project outcomes will provide an improved understanding of the role of folate and related B vitamins in brain health, and the epigenetic mechanisms involved. The results are expected to provide scientific substantiation to support nutritional strategies for better brain health across the lifecycle.

Pregnancy homocysteine and cobalamin status predict childhood metabolic health in the offspring

BACKGROUND

Inadequate pregnancy cobalamin status has been associated with adverse offspring metabolic health in Indian and Nepalese studies. Studies of pregnancy cobalamin status and mid-childhood health outside of Asia are scarce.

METHODS

Associations between pregnancy fasting plasma total homocysteine (tHcy), cobalamin status (plasma cobalamin, holotranscobalamin (holoTC), methylmalonic acid (MMA)) and mid-childhood metabolic score (MetSco) ((including fat mass index (zFMI), homeostatic model assessment of insulin resistance (zHOMA-IR) and dyslipidemia (zTG - zHDLc)/2) z-scores)) were investigated in a prospective study of 293 mother-child dyads.

RESULTS

Highest versus low-mid pregnancy tHcy tertile was associated with higher mid-childhood MetSco, specifically with higher child zFMI. Stratifying by sex, the maternal tHcy-child MetSco association was limited to boys and confirmed for zFMI and zHOMA-IR. The maternal tHcy-child zFMI association was not mediated by birth weight z-score. First trimester plasma cobalamin was not associated with child outcomes, but other indicators of cobalamin status were. Lowest versus mid-high plasma holoTC tertile was associated with MetSco (specifically zFMI and zHOMA-IR) and highest versus low-mid plasma MMA tertile with higher MetSco and dyslipidemia in boys.

CONCLUSIONS

Moderately elevated pregnancy tHcy and low cobalamin status were associated with mid-childhood metabolic score in boys. The pregnancy tHcy-child zFMI association was not mediated by birth weight.

IMPACT

Fasting plasma total homocysteine (tHcy) during pregnancy and low cobalamin status during early pregnancy are associated with mid-childhood metabolic score and its components in the offspring. These findings were only significant in male offspring. The study provides new evidence that impaired one carbon metabolism during pregnancy is associated with negative health outcomes in the offspring, in a population with low prevalence of cobalamin deficiency. The maternal-offspring associations were observed in the functional markers of cobalamin status (holotranscobalamin and methylmalonic acid) and tHcy, not with plasma cobalamin concentration. Screening for low pregnancy cobalamin status should be considered.

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

SCOPE

Folic acid supplementation during pregnancy may lead to an imbalance when vitamin B12 intake is low (folate trap) and may affect child's growth.

METHODS

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.

RESULTS

Imbalanced total intakes (folate > 430 µg day^-1 combined with B12 < 5.5 µg 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 > 745 nmol L^-1 and plasma B12 < 172 pmol 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.

CONCLUSION

Low maternal dietary B12 intake and elevated methylmalonic acid rather than imbalanced vitamins are associated with higher birthweight, suggesting that low maternal B12 can predispose the infants for later obesity.

Maternal vitamin B12 deficiency and perinatal outcomes in southern India

BACKGROUND

Vitamin B12 deficiency during pregnancy has been associated with adverse maternal and infant health outcomes. Few prospective studies have investigated vitamin B12 status early in pregnancy, and its links to infant vitamin B12 status, particularly in India where the burden of vitamin B12 deficiency is estimated to be the highest globally. The objective of this study was to examine the associations of maternal vitamin B12 biomarkers with neonatal vitamin B12 status.

METHODS

Pregnant women (~12 weeks' gestation) were enrolled in a perinatal cohort study in Bangalore, India. Total vitamin B12, methylmalonic acid (MMA), and homocysteine concentrations were evaluated in maternal samples at enrollment and in neonates at birth using cord blood. Linear and binomial regression models were used to evaluate the associations of maternal vitamin B12 biomarkers with neonatal vitamin B12 status and perinatal outcomes.

RESULTS

A total of 63.2% of women had vitamin B12 deficiency (<148 pmol/L), 87.2% had vitamin B12 insufficiency (<221 pmol/L), and 47.3% had impaired vitamin B12 status (vitamin B12<148 pmol/L and MMA>0.26μmol/L) at enrollment; 40.8% of neonates had vitamin B12 deficiency, 65.6% were insufficiency, and 38.1% had impaired vitamin B12 status at birth. Higher maternal vitamin B12 concentrations at enrollment were associated with increased neonatal vitamin B12 concentrations (β(SE): 0.40 (0.05); p<0.0001) and lower risk of neonatal vitamin B12 deficiency (Risk Ratio [RR]: 0.53; 95% CI: [0.43, 0.65]; p<0.0001). Maternal vitamin B12 deficiency (RR: 1.97 [1.43, 2.71]; p<0.001), insufficiency (RR: 2.18 [1.23, 3.85]; p = 0.007), and impaired vitamin B12 status (RR: 1.49 [1.13, 1.97]; p = 0.005) predicted a two-fold increase in the risk of neonatal vitamin B12 deficiency at birth.

CONCLUSIONS

The prevalence of vitamin B12 deficiency was high early in pregnancy and predicted neonatal vitamin B12 status. Future research is needed to determine the role of vitamin B12 in the development of pregnancy and infant outcomes, and to inform screening and interventions to improve maternal and child health.

Investigating the causal effect of maternal vitamin B12 and folate levels on offspring birthweight

BACKGROUND

Lower maternal serum vitamin B12 (B12) and folate levels have been associated with lower offspring birthweight, in observational studies. The aim of this study was to investigate whether this relationship is causal.

METHODS

We performed two-sample Mendelian randomization (MR) using summary data on associations between genotype-B12 (10 genetic variants) or genotype-folate (four genetic variants) levels from: a genome-wide association study of 45 576 individuals (sample 1); and both maternal- and fetal-specific genetic effects on offspring birthweight from the latest Early Growth Genetics consortium meta-analysis with 297 356 individuals reporting their own birthweight and 210 248 women reporting their offspring's birthweight (sample 2). We used the inverse variance weighted method, and sensitivity analyses to account for pleiotropy, in addition to excluding a potentially pleiotropic variant in the FUT2 gene for B12 levels.

RESULTS

We did not find evidence for a causal effect of maternal or fetal B12 levels on offspring birthweight. The results were consistent across the different methods. We found a positive causal effect of maternal folate levels on offspring birthweight [0.146 (0.065, 0.227), which corresponds to an increase in birthweight of 71 g per 1 standard deviation higher folate]. We found some evidence for a small inverse effect of fetal folate levels on their own birthweight [-0.051 (-0.100, -0.003)].

CONCLUSIONS

Our results are consistent with evidence from randomized controlled trials that higher maternal folate levels increase offspring birthweight. We did not find evidence for a causal effect of B12 levels on offspring birthweight, suggesting previous observational studies may have been confounded.

Maternal vitamin B12 status in early pregnancy and its association with birth outcomes in Canadian mother-newborn Dyads

Vitamin B12 (B12) is a co-enzyme essential for fetal growth and development. Lower maternal B12 status has been associated with preterm birth (<37 gestational weeks) and low birth weight (<2500 g), which are linked to morbidity and mortality across the lifespan. In Canada, 17-25 % of women in early pregnancy had a serum total B12 concentration <148 pmol/l and maternal total B12 concentration decreased throughout pregnancy. This study aimed to determine the association between maternal B12 status and birth outcomes in Canadian mother-newborn dyads. A secondary analysis of 709 mother-newborn dyads in British Columbia (BC), Canada, was conducted. Bio-banked first- (n 656) and second-trimester (n 709) maternal serum samples of apparently healthy South Asian (50 %) and European (50 %) women from the BC Prenatal Genetic Screening Program were quantified for B12 biomarkers (total B12, holotranscobalamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy)). Obstetric history and birth outcome data were obtained from the BC Perinatal Data Registry. All associations were determined using multiple linear regression. Maternal serum total B12, holoTC, MMA and tHcy had a mean weekly decrease of 3·64 pmol/l, 1·04 pmol/l, 1·44 nmol/l and 0·104 μmol/l, respectively (P < 0·001). Despite a total B12 concentration <148 pmol/l among 20-25 % of the women, maternal B12 biomarker concentrations were not associated with birth weight z-score, head circumference z-score and gestational age at birth (P > 0·05). Additional research in women at high risk of adverse birth outcomes and the association between maternal B12 status and functional, for example, cognitive, outcomes is needed.

Maternal plasma folate concentration is positively associated with serum total cholesterol and low-density lipoprotein across the three trimesters of pregnancy

Increased first-trimester low-density lipoprotein (LDL-C) concentration has been associated with adverse pregnancy outcomes, such as gestational diabetes. The B vitamins folate, B-6, and total B-12 are key for the methyl group-dependent endogenous synthesis of phosphatidylcholine, which is needed for lipoprotein synthesis, e.g., very low-density lipoprotein (VLDL), the precursor of circulating LDL-C. Maternal B-vitamin concentration usually declines across trimesters. Whether changes in maternal B-vitamin concentrations are associated with total cholesterol (TC), triglycerides (TG), and lipoprotein concentrations is unknown. Therefore, we explored the association between plasma folate, vitamin B-6 in the form of pyridoxal 5′-phosphate (PLP), and total B-12 with serum TC, LDL-C, HDL-C, and TG concentrations across trimesters. This secondary analysis used data of a prospective pregnancy cohort study included apparently healthy adult women (n = 179) from Rio de Janeiro, Brazil. The biomarkers were measured in fasting blood samples collected at 5–13, 20–26, and 30–36 weeks of gestation. The associations between B vitamins and lipid concentrations across trimesters were explored using linear mixed-effect models. Among B vitamins, only plasma folate was positively associated with TC (β = 0.244, 95% CI 0.034–0.454) and LDL-C (β = 0.193, 95% CI 0.028–0.357) concentrations. The positive relationship of maternal folate and TC and LDL-C concentrations may indicate the importance of folate as a methyl donor for lipoprotein synthesis during pregnancy.

Maternal Plasma Pyridoxal 5'-Phosphate Concentration Is Inversely Associated with Plasma Cystathionine Concentration across All Trimesters in Healthy Pregnant Women

BACKGROUND

Vitamin B-6 (B-6), in the form of pyridoxal 5'phosphate (PLP), is critical for one-carbon metabolism reactions and cellular function. Plasma PLP concentration decreases throughout pregnancy, but the functional consequences of this have not been studied. Plasma cystathionine is a sensitive indicator of suboptimal B-6 status in healthy adults.

OBJECTIVES

The aim of this study was to determine the relation between plasma PLP and cystathionine concentrations, and to assess longitudinal changes in plasma concentrations of metabolites of one-carbon metabolism, including total homocysteine (tHcy), cysteine, methionine, glycine, serine, and glutathione, over the course of pregnancy.

DESIGN

This was a prospective cohort study of 186 healthy Brazilian pregnant women (20-40 y). Plasma PLP and metabolite concentrations were quantified in fasting maternal blood samples collected between 5-13, 20-26, and 30-36 weeks of gestation. Linear mixed regression models were used to determine the association of 1) first-trimester PLP tertiles, and 2) the variation of PLP concentration throughout pregnancy, with related metabolite concentrations across weeks of gestation.

RESULTS

Median (IQR) PLP concentration decreased from 36.2 (29.2-44.5) to 21.0 (15.9-26.0) to 16.8 (12.9-21.4) nmol/L in the first, second, and third trimester, respectively, whereas cystathionine concentration increased from 63.2 (49.7-78.9) to 122 (98.0-167) to 143 (114-193) nmol/L, respectively (both P < 0.001). The variation of PLP throughout pregnancy was inversely associated with cystathionine concentration across weeks of gestation, after adjusting for confounding factors; β (95% CI) = -0.387 (-0.752, -0.219), P = 0.04. This association significantly differed by trimester and was strongest in the third trimester. Plasma concentrations of glycine, serine, methionine, cysteine, and tHcy decreased, and that of glutathione increased, between the first and second trimesters (all P < 0.05).

CONCLUSIONS

The variation of PLP concentration predicted cystathionine concentration throughout pregnancy. Increases in plasma cystathionine across trimesters may reflect maternal intracellular B-6 deficiency.

Vitamin B12 Intake From Animal Foods, Biomarkers, and Health Aspects

The EAT-Lancet commission recently suggested that transformation to healthy diets by 2050 will require a reduction of at least 50% in consumption of foods such as red meat and sugar, and a doubling in the global consumption of fruits, vegetables, nuts, and legumes. A diet rich in plant-based foods and with fewer animal source foods confers both improved health and environmental benefits. Notably, the risk of vitamin B12 deficiency increases when consuming a diet low in animal products. Humans are dependent on animal foods such as dairy products, meat, fish and eggs. Vitamin B12 deficiency is common worldwide, especially in populations with low consumption of animal foods because of low socioeconomic status, ethical reasons, or because of their lifestyle (i.e., vegans). According to the European Food Safety Authoroty, the recommended adequate intake of vitamin B12 is 4.0 μg/d for adults, and vitamin B12 requirements are higher during pregnancy and lactation. Infants and children from deficient mothers and elderly people are at risk for vitamin B12 deficiency. Diagnosis of vitamin B12 deficiency is hampered by low specificity of available biomarkers, and there is no consensus yet regarding the optimal definition of low vitamin B12 status. In general, a combination of at least two biomarkers is recommended. Therefore, this review presents an overview of vitamin B12 biochemistry and its biomarkers. We further summarize current recommendations of vitamin B12 intake, and evidence on the associations of vitamin B12 intake from different nutrient-dense animal foods with vitamin B12 status markers. Finally, potential consequences of low vitamin B12 status on different health outcomes for pregnant women, infants and elderly are presented.