Dependence of bioavailability of folic acid and (6S)-5-methyltetrahydrofolate on baseline red blood cell folate concentrations in infants

Red blood cell folate concentrations increase more after supplementation with [6 S]-5-methyltetrahydrofolate than with folic acid in women of childbearing age

Divergence between dietary folate intake and concentrations in the serum and red blood cells of aging males in the United States

Red blood cell (RBC) folate concentrations are a potential biomarker of folate-sensitive neural tube defect (NTD) risk in the population. The purpose of this analysis was to describe women in the U.S. population with RBC folate concentrations below those associated with optimal NTD prevention. We used data from the 2007 to 2012 National Health and Nutrition Examination Survey (NHANES) to assess the RBC folate status of U.S. women of childbearing age relative to risk categories for NTD risk based on RBC folate concentrations. We defined suboptimal RBC folate concentrations as those associated with a prevalence of ≥9 NTDs per 10,000 live births. Among nonpregnant women age 12 to 49 years, 22.8% (95% Confidence Interval: 21.1, 24.6) had suboptimal RBC folate concentrations. Women had greater odds of having a suboptimal RBC folate concentration if they did not use dietary supplements containing folic acid; had mandatorily fortified enriched cereal grain products as their only source of folic acid; were non-Hispanic black or Hispanic; or were current smokers. Based on RBC folate concentrations, we would predict that the majority of U.S. women of reproductive age are not at increased risk for folate sensitive NTDs in the presence of mandatory folic acid fortification. Prevention policies and programs can be aimed at population subgroups identified as having higher predicted risk for folate-sensitive NTDs based on RBC folate concentrations.

Are maternal folate and vitamin B12 concentrations associated with first-trimester placental growth? Maternal folate concentrations and commencement of folic acid supplements prior to conception, as compared to following conception, are positively associated with first-trimester placental volume (PV), whereas no associations were found for maternal vitamin B12 concentrations. Besides the protective effect of folic acid supplement use against neural tube defects and other adverse birth outcomes, the preconceptional commencement of folic acid supplements is positively associated with postpartum placental size, although conflicting outcomes have been reported. Studies in mice show an association with vitamin B12 deficiency and decreased placental weight postpartum. Between January 2010 and December 2020, 480 pregnancies (727 longitudinal ultrasound measurements) with known maternal folate and/or vitamin B12 blood concentrations in the first trimester and 875 pregnancies (1430 longitudinal ultrasound measurements) with known timing of folic acid supplement initiation were included in the Rotterdam Periconception Cohort, a prospective, hospital-based observational cohort. Red blood cell (RBC) folate and serum vitamin B12 concentrations were determined in first-trimester maternal blood, and the timing of folic acid supplement use was collected using validated questionnaires. PV was measured from serial 3-dimensional ultrasounds performed at 7, 9, and 11 weeks of gestation. Linear mixed models were used to assess the associations between maternal folate and vitamin B12 concentrations with first-trimester PVs. Analyses were adjusted for gestational age at ultrasound, maternal age, BMI, geographical background, education level, parity, smoking, mode of conception, and the other B vitamins. For validation, the association between the timing of folic acid supplement initiation (pre- or postconception) and PV was assessed. The median RBC folate concentration was 1395 nmol/l (IQR 1169-1588) and the median serum vitamin B12 concentration was 314 pmol/l (IQR 241-391). For RBC folate, the smallest PVs were found in women in the lowest quartile, with the largest difference as compared to women in the fourth quartile: 3√PV (β = -0.141, 95% CI = -0.249 to -0.033, P = 0.010), corresponding to a 1.79 cm3 (-18.7%) and a 6.99 cm3 (-9.9%) smaller PV at 7 and 11 weeks of gestation, respectively. Additionally, PV was significantly smaller in women who initiated folic acid supplements following rather than prior to conception: 3√PV (β=-0.129, 95% CI = -0.207 to -0.051, P = 0.001) corresponding to a 1.69 cm3 (-16.9%) and a 6.62 cm3 (-8.9%) smaller PV at 7 and 11 weeks of gestation, respectively. We found no significant association between maternal serum vitamin B12 concentrations and PV. The observational design of this study does not exclude residual confounding, and our hospital-based study population, with mostly adequate RBC folate and serum vitamin B12 concentrations, could limit the generalizability of our results. Our results emphasize the importance of the preconceptional commencement of folic acid supplements to achieve adequate maternal RBC folate concentrations, which could support optimal placental growth during the first trimester and also protect against neural tube defects and other adverse birth outcomes. This study was funded by the Department of Obstetrics and Gynecology and the Department of Developmental Biology of the Erasmus MC, University Medical Center, Rotterdam, the Netherlands. K.D.S. was in receipt of funding from the Biotechnology and Biological Sciences Research Council (BBSRC) (BB/K017810/1). The authors declare that they have no conflict of interests. NTR4356.

BACKGROUND AND AIM: Adequate folate is essential for many physiological processes, and low folate levels have been associated with cardiovascular disease, anemia, and various health outcomes, including developmental outcomes in relation to low folate status during pregnancy. On the other hand, perfluoroalkyl substance (PFAS) have been associated with multiple health outcomes, with scarce data on the mechanistic pathways by which these substances exert their effects. Our objective is to investigate the individual and joint associations of a mixture of PFAS with red blood cell (RBC) folate concentrations in the adult U.S. population. METHODS: We assessed associations of five chemical biomarkers of 8961 participants ages 18-80 from the U.S. National Health and Nutrition Examination Survey (2007-2016). RBC folate were quantified using a micro bioassay and mass spectrometry. We estimated covariate-adjusted independent and joint associations between PFAS and RBC folate concentrations and triangulated evidence from three approaches developed to examine chemical mixtures: Exposome Wide Association (ExWAS), Bayesian Kernel Regression (BKMR), and Quantile G-Computation (QgComp). We additionally evaluated potential effect modification by sex. RESULTS:The geometric mean RBC folate was 468 µg/L (geometric standard deviation: 1.5 µg/L). In ExWAS analyses, all PFAS were associated with lower RBC folate concentrations. For instance, a twofold increase in Perfluorononanoic acid was associated with a 10% (95% CI: 9%, 11%) decrease in RBC folate concentrations. BKMR and QgComp showed convergent results with a one quartile increase in the PFAS mixture associated with comparable decreases in RBC folate concentrations. Associations did not differ between males and females. CONCLUSIONS:This study is the first to examine the associations between PFAS and RBC folate concentrations in a nationally representative sample. These results may deepen our understanding of the mechanistic pathways by which PFAS impact health outcomes. KEYWORDS: PFAS,Folate,Methods,BKMR,ExWAS,G-Computation

Maternal folate supplementation reduces offspring risk for neural tube defects (NTDs) and other congenital abnormalities. Maternal red blood cell (RBC) folate concentrations of >906 nmol/L have been associated with the lowest risk of having a neural tube defect affected pregnancy. Mood disorders (e.g., depression, bipolar disorder) are common among women and can be associated with folate deficiency. Thus, pregnant women with histories of mood disorders may be prone to RBC folate levels insufficient to provide optimal protection against neural tube defects. Although previous studies have assessed RBC folate concentrations in pregnant women from the general population, none have looked specifically at a group of pregnant women who have a history of a mood disorder. We collected data about RBC folate concentrations and folic acid supplement intake during early pregnancy (<161 days gestation) from n = 24 women with histories of mood disorders. We also collected information about offspring congenital abnormalities and birth weight. Among women with histories of mood disorders, the mean RBC folate concentration was 674 nmol/L (range, 362-1105 nmol/L). Only 12.5% (n = 3) of the women had RBC folate concentrations >906 nmol/L, despite all participants reporting current daily use of folic acid supplements. Data regarding offspring were available for 22 women: birth weights ranged from 2296 g to 4819 g, and congenital abnormalities were identified in two (hypoplastic left heart, annular pancreas). Data from this exploratory case series suggest a need for future larger scale controlled studies investigating RBC folate concentrations in early pregnancy and offspring outcomes among women with and without histories of mood disorders.

To the Editor: Low concentrations of folate are associated with an increased risk of neural tube defects, while preconception supplementation with folic acid attenuates that risk. 1 The government of Canada mandated that all flour and some corn and rice products be fortified with folic acid, a policy that was fully implemented by January 1998 [G. Carson, Grain Based Products, Robin Hood Multifoods, Inc., Canada, personal communication, 2001]. We studied the effect of this fortification program among women of reproductive age, age 18–42 years. Comparing data from before and after fortification, we considered all red blood cell (RBC) folate and serum vitamin B12 (Se B12) samples analyzed by MDS Laboratories (Toronto, Ontario, Canada), which provides diagnostic services to approximately one-third of community-based patients in the province of Ontario. These tests, paid for under Ontario’s publicly funded universal Ontario Health Insurance Plan, were ordered on clinical grounds, but the reasons were not available. Vitamin concentrations were determined by competitive protein binding (Bio-Rad Laboratories, Mississauga, Ontario, Canada), with a maximum reporting limit of 1,450 nmol/L for RBC folate and 1,600 pmol/L for Se B12. Identifiers were removed to protect patient confidentiality, and the Ethics Review Boards of Sunnybrook and Women’s College Health Sciences Centre and MDS Laboratories approved this study. A total of 8,408 consecutive, nonredundant samples were analyzed for the intervals of January 1, 1996 to December 31, 1997 (prefortification) and 30,061 samples for January 1, 1998 to December 31, 2000 (postfortification). The mean participant age was 31.8 years for both periods. The geometric mean RBC folate concentration rose from 527 nmol/L prefortification to 741 nmol/L after January 1, 1998 (mean difference 214 nmol/L) (Table 1 and Figure 1). The respective mean concentrations for Se B12 were 276 and 270 pmol/L (mean difference −6 pmol/L) (Table 1 and Figure 1). Similar trends were seen for the fifth-percentile concentrations of RBC folate and Se B12 (Table 1). Table 1: Red Blood Cell (RBC) -Folate and Serum Vitamin B12 (Se B12) Concentrations before and after Folic AcidFIGURE 1: Mean and 95% confidence interval concentrations of red blood cell (RBC) folate (upper curve) and serum vitamin B12 (Se B12; lower curve) after folic acid fortification (vertical line).We did not obtain information on the clinical indications for folate and cobalamin (vitamin B12) testing, which is a potential source of study bias. Furthermore, we did not account for use of folic acid supplements, which, in addition to lead-time compliance with folate fortification by the milling industry, could also explain the rise in RBC folate concentrations before January 1998. Because Se B12 levels have remained nearly constant over time, however, multivitamin supplement use could not account for more than a small portion of the rise in RBC folate. As in the U.S. general population, 2,3 Canada’s national folic acid fortification program has probably enhanced the folate status of women of reproductive age. Experimental data have demonstrated that withdrawal of dietary folic acid for as little as 12 weeks can significantly reduce RBC folate concentrations in women, 4 suggesting that an increase in RBC folate concentrations would be evident soon after the addition of folic acid to flour. We must highlight the fact that Se B12 concentrations have remained relatively constant since folic acid food fortification was introduced. Although cobalamin deficiency too has been implicated in the formation of neural tube defects, 5 its detection before and during pregnancy is a point of controversy. 6–8 Thus, with the rising popularity of ovo-lacto vegetarianism, 9 unrecognized vitamin B12 insufficiency may become an issue among women of reproductive age. 6 There is an urgent need to consider both the addition of synthetic vitamin B12 to current fortification programs 10 and the long-term health consequences of fortifying flour with folic acid but not cobalamin. 11 Joel G. Ray Marian J. Vermeulen Sheila C. Boss David E. C. Cole

Folate plays one of the most important functions for nucleotide biosynthesis and cellular methylation reactions in cells. Folate-mediated one-carbon metabolism is essential for metabolic processes in the human body. During periods of rapid cell growth, such as perinatal period, increased amounts of folate are required. The determination of red blood cell (RBC) folate concentration levels is the most accurate indicator of long-term folate level status in the body. This prospective study determined RBC folate concentration levels on the first day of life from umbilical cord blood samples in the whole group of full-term newborns (n = 150), who were hospitalized at the Department of Neonatology at the University Hospital in Bratislava. Immunochemical analysis for the determination of folate levels in erythrocytes was performed (Roche Diagnostics, Germany). Mothers were asked to select different types of food and use folic acid or other multivitamin supplements containing also folic acid. Our results of RBC folate ranged from 625 to 1748 ng/mL (5th–95th percentile). The median was 935 ng/mL and deficiency was not observed in any sample. RBC folate concentration levels in newborns due to mother’s intake of multivitamin supplements were significantly increased (p = 0.02). No differences were observed in the levels of RBC folate concentration when mothers used only folic acid. The RBC folate concentration tended to change based on many factors on both the mother’s and the newborn’s sides. Our results showed different results of RBC folate when focused on neonatal period and maternal intake of vitamins during pregnancy.

A distinct shift towards higher folate concentrations has emerged in Canada. These higher concentrations have known benefits, including prevention of neural tube defects, but concerns have been raised regarding potential associations with adverse health outcomes. The aim of this research was to propose cut-offs for high red blood cell (RBC) folate concentrations and identify their correlates. RBC folate was measured in a nationally representative cross-sectional sample of Canadians (N = 5248) aged 6 to 79 years. RBC folate concentrations were adjusted from the IMMULITE 2000 immunoassay to a microbiologic assay. The population was characterized at 3 RBC folate cut-offs: 1450 nmol/L, 1800 nmol/L, and 2150 nmol/L. We used t tests to examine differences by age, sex, income, and body mass index (BMI) at each cut-off and logistic regression to explore associations with folic acid supplement intake. The prevalence of high RBC folate was 16%, 6%, and 2% at thresholds of 1450 nmol/L, 1800 nmol/L, and 2150 nmol/L, respectively. Females, those aged 60 to 79 years, and overweight or obese participants had the greatest prevalence of having high RBC folate at each cut-off. Folic acid supplement users were more likely than non-users to have high RBC folate concentrations. Older age, higher BMI, and folic acid supplement use were identified as correlates of high folate status. A high RBC folate concentration cut-off will advance the field towards consistent measurement and reporting of high folate status. This may facilitate future investigation of associations between RBC folate concentrations at the upper end of the distribution and health outcomes.

For the first time (N = 6291), a study was undertaken to estimate associations between the concentratio ns of red blood cell folate (RBCF) and concentration of six perfluoroalkyl acids (PFAAs), namely, perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUnDA) for US adults aged ≥20 years by fitting regression models for the data from National Health and Nutrition Examination Survey for 2007-2014. In almost consistent fashion, increasing concentrations of PFAAs were associated with decreasing concentrations of RBCF. For the total population, for a 10% increase in the concentrations of PFOA, PFOS, PFDA, PFHxS, PFNA, and PFUnDA, percent decreases in RBCF concentrations were found to be 0.33%, 0.66%, 0.83%, 0.16%, 0.89%, and 0.43%, respectively. RBCF concentrations of PFAAs were found to be 1104, 1042, 100, and 936 nmol/L across the four quartiles of PFOS; 112, 1068, 1009, and 948 nmol/L across the four quartiles of PFDA; 1125, 1054, 1005, and 967 nmol/L across the four quartiles of PFNA; and 1099, 1094, 989, and 952 nmol/L across the four quartiles of PFUnDA. Perfluorinated carboxylic acids with carbon chain length > 8 decreased concentrations of RBCF to a greater degree than those carbon chain length ≤ 8. Perfluorinated chemicals with a sulfonic group with carbon chain length > 6 decreased concentrations of RBCF to a greater degree than those carbon chain length ≤ 6. The degree to which concentrations of RBCF decrease varied by age, gender, and race/ethnicity. Non-Hispanic blacks as compared to non-Hispanic whites and Hispanics had the lowest decreases in RBCF concentrations. Mechanisms responsible for negative associations between RBCF and PFAA concentrations are not known and will need to be researched further.

Extremely high concentration of folates in premature newborns: case reports. Folates are a group of water soluble compounds, which are important for metabolic processes in human body. These are important during periods of rapid cell growth. The most accurate indicator of long-term folate level status in the body is the determination of red blood cell (RBC) folate concentrations. The optimal level of RBC folate is not known in neonatal period. Authors discuss the reasons for extremely high level of RBC folate concentrations. In our work we present the cases of two premature newborns with extremely high level of RBC folate concentrations, which were analyzed immunochemically on the first day of life and after six weeks of life. In both cases we measured RBC folate concentrations on the 1st day of life. After 6 weeks we found extremely high RBC folate concentration level (5516.67 ng/ml) in the first case after RBC transfusions. In second case after two months of life the RBC folate concentration level was doubled (2335.1 ng/ml) until 24 hours after RBC transfusion compared to levels after birth. The normal range of RBC folate values vary in newborns. The upper limit of daily dose of folic acid in pregnancy and neonatal period is not known. On the other hand it is an easily excreted water-soluble vitamin but in premature newborn it can lead to the disruption of metabolic balance and slow its degradation. Some factors can have an impact on RBC folate concentration. Blood transfusion can be one of the main influences on RBC folate concentration. To clarify these mechanisms further studies are required (Ref. 29).

Folate is critical for many physiological processes, and low folate levels have been associated with a wide range of health outcomes, including chronic diseases and developmental outcomes. Many environmental chemicals are suspected to contribute to the etiology of health outcomes related to folate deficiency. However, little is known about how these pollutants influence folate levels as potential mechanistic pathways. To investigate the individual and joint associations between a mixture of 39 pollutants and red blood cell (RBC) folate concentrations in the U.S. We used available data on 27,938 participants, aged 18-80 from the U.S. National Health and Nutrition Examination survey (2007-2016), with available RBC folate concentrations and 39 environmental pollutants' concentrations. We estimated covariate-adjusted independent and joint associations between environmental pollutants and RBC folate, and compared evidence from two complimentary mixture approaches: exposome-wide association study (ExWAS) and quantile-based g computation (Q-gcomp). In the ExWAS analysis, 12 environmental chemicals, including metals (cadmium, arsenic, lead, and mercury), perfluoroalkyl substances, phthalates, phenols and parabens, and polycyclic aromatic hydrocarbons, were inversely associated with RBC folate, whereas four environmental pollutants, including metals (manganese and selenium) and two phthalate metabolites, were positively associated with RBC folate. Q-gcomp showed convergent results with the ExWAS analysis; a quartile increase in the metal and PFAS mixtures was significantly associated with a decrease of -38.4 ng/mL (95%CI: -52.3, -24.4) and -48.9 ng/mL (95%CI: -57.6, -39.6) in RBC folate concentrations, respectively. The present study shows that higher exposure to PFASs, metals, and PAHs are associated with lower RBC folate concentrations. However, given the cross-sectional design, we cannot make inferences about the directionality of the observed associations.

Vitamin B-12 metabolism in HIV-infected patients in the age of highly active antiretroviral therapy: role of homocysteine in assessing vitamin B-12 status

Bringing clarity to the role of MTHFR variants in neural tube defect prevention

Folic acid supplementation and malaria susceptibility and severity among people taking antifolate antimalarial drugs in endemic areas.