Red Blood Cell Folate Concentrations Research Articles

Prevalence and correlates of high red blood cell folate concentrations in the Canadian population using 3 proposed cut-offs.

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.

Assessing the association between the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism and blood folate concentrations: a systematic review and meta-analysis of trials and observational studies

The methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism is a risk factor for neural tube defects. The T allele produces an enzyme with reduced folate-processing capacity, which has been associated with lower blood folate concentrations. We assessed the association between MTHFR C677T genotypes and blood folate concentrations among healthy women aged 12-49 y. We conducted a systematic review of the literature published from January 1992 to March 2014 to identify trials and observational studies that reported serum, plasma, or red blood cell (RBC) folate concentrations and MTHFR C677T genotype. We conducted a meta-analysis for estimates of percentage differences in blood folate concentrations between genotypes. Forty studies met the inclusion criteria. Of the 6 studies that used the microbiologic assay (MA) to measure serum or plasma (S/P) and RBC folate concentrations, the percentage difference between genotypes showed a clear pattern of CC > CT > TT. The percentage difference was greatest for CC > TT [S/P: 13%; 95% credible interval (CrI): 7%, 18%; RBC: 16%; 95% CrI: 12%, 20%] followed by CC > CT (S/P: 7%; 95% CrI: 1%, 12%; RBC: 8%; 95% CrI: 4%, 12%) and CT > TT (S/P: 6%; 95% CrI: 1%, 11%; RBC: 9%; 95% CrI: 5%, 13%). S/P folate concentrations measured by using protein-binding assays (PBAs) also showed this pattern but to a greater extent (e.g., CC > TT: 20%; 95% CrI: 17%, 22%). In contrast, RBC folate concentrations measured by using PBAs did not show the same pattern and are presented in the Supplemental Material only. Meta-analysis results (limited to the MA, the recommended population assessment method) indicated a consistent percentage difference in S/P and RBC folate concentrations across MTHFR C677T genotypes. Lower blood folate concentrations associated with this polymorphism could have implications for a population-level risk of neural tube defects.

Folate and Vitamin B12 Deficiency Among Non-pregnant Women of Childbearing-Age in Guatemala 2009-2010: Prevalence and Identification of Vulnerable Populations.

Information on folate and vitamin B12 deficiency rates in Guatemala is essential to evaluate the current fortification program. The objectives of this study were to describe the prevalence of folate and vitamin B12 deficiencies among women of childbearing age (WCBA) in Guatemala and to identify vulnerable populations at greater risk for nutrient deficiency. A multistage cluster probability study was designed with national and regional representation of nonpregnant WCBA (15-49years of age). Primary data collection was carried out in 2009-2010. Demographic and health information was collected through face-to-face interviews. Blood samples were collected from 1473 WCBA for serum and red blood cell (RBC) folate and serum vitamin B12. Biochemical concentrations were normalized using geometric means. Prevalence rate ratios were estimated to assess relative differences among different socioeconomic and cultural groups including ethnicity, age, education level, wealth index and rural versus urban locality. National prevalence estimates for deficient serum [<10nmol per liter (nmol/L)] and RBC folate (<340 nmol/L) concentrations were 5.1% (95% CI 3.8, 6.4) and 8.9% (95% CI 6.7, 11.7), respectively; for vitamin B12 deficiency (<148pmol/L) 18.5% (95% CI 15.6, 21.3). Serum and RBC folate deficiency prevalences were higher for rural areas than for urban areas (8.0 vs. 2.0% and 13.5 vs. 3.9%, respectively). The prevalence of RBC folate deficiency showed wide variation by geographic region (3.2-24.9%) and by wealth index (4.1-15.1%). The prevalence of vitamin B12 deficiency also varied among regions (12.3-26.1%). In Guatemala, folate deficiency was more prevalent among indigenous rural and urban poor populations. Vitamin B12 deficiency was widespread among WCBA. Our results suggest the ongoing need to monitor existing fortification programs, in particular regarding its reach to vulnerable populations.

Association Between Use of Oral Contraceptives and Folate Status: A Systematic Review and Meta-Analysis.

To conduct a systematic review and meta-analysis of the effect of oral contraceptive use on plasma and red blood cell (RBC) folate concentrations. We searched Medline, EMBASE, Web of Science, and the Cochrane library for human studies published from inception to June 2013 evaluating oral contraceptive use and folate status. Case-control studies, cohort studies, and clinical trials were included. A random-effects model of outcomes was used for the meta-analysis. A total of 2831 women in 17 studies were included in the analysis. In those whose plasma folate concentrations were available, there was a significant folate-lowering effect of oral contraceptives observed (mean reduction 1.27 µg/L; 95% CI 1.85 to 0.69, P < 0.001). Similarly, after analyzing data from 1389 women in 12 studies whose RBC folate concentrations were available, significantly lower folate status was observed among oral contraceptive users (mean reduction 59.32 µg/L; 95% CI 58.03 to 23.04, P < 0.001). Because of the reduction in blood folate concentrations associated with the use of oral contraceptives, it is critical for women of childbearing age to continue folate supplementation during oral contraceptive use.

U.S. women of childbearing age who are at possible increased risk of a neural tube defect-affected pregnancy due to suboptimal red blood cell folate concentrations, National Health and Nutrition Examination Survey 2007 to 2012.

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.

Assessing the association between natural food folate intake and blood folate concentrations: a systematic review and Bayesian meta-analysis of trials and observational studies.

Folate is found naturally in foods or as synthetic folic acid in dietary supplements and fortified foods. Adequate periconceptional folic acid intake can prevent neural tube defects. Folate intake impacts blood folate concentration; however, the dose-response between natural food folate and blood folate concentrations has not been well described. We estimated this association among healthy females. A systematic literature review identified studies (1 1992–3 2014) with both natural food folate intake alone and blood folate concentration among females aged 12–49 years. Bayesian methods were used to estimate regression model parameters describing the association between natural food folate intake and subsequent blood folate concentration. Seven controlled trials and 29 observational studies met the inclusion criteria. For the six studies using microbiologic assay (MA) included in the meta-analysis, we estimate that a 6% (95% Credible Interval (CrI): 4%, 9%) increase in red blood cell (RBC) folate concentration and a 7% (95% CrI: 1%, 12%) increase in serum/plasma folate concentration can occur for every 10% increase in natural food folate intake. Using modeled results, we estimate that a natural food folate intake of ≥450 μg dietary folate equivalents (DFE)/day could achieve the lower bound of an RBC folate concentration (~1050 nmol/L) associated with the lowest risk of a neural tube defect. Natural food folate intake affects blood folate concentration and adequate intakes could help women achieve a RBC folate concentration associated with a risk of 6 neural tube defects/10,000 live births.

The Effects of Folic Acid‐Fortified Food and Nutrition Education on Folate Nutritional Status and Behavioral Capability in Korean Women of Child‐Bearing Age

The purpose of the study was to investigate the effects of folic acid‐fortified food and nutrition education on folate status and behavioral capability of Korean women of child‐bearing age. Instant rice fortified with 400 μg of folic acid per serving (one bowl) was developed. Seventy‐eight women aged between 19 and 35 who were at risk of folate deficiency were randomly assigned to 'non‐fortified food group', 'fortified food group', 'non‐fortified food and nutrition education group' and 'fortified food and nutrition education group'. All the subjects were asked to eat one bowl of fortified or non‐fortified food blindly once a day for 4 weeks. Nutrition education based on social cognitive theory was given to nutrition education group once a week. Questionnaire survey and hematological analysis were performed both at the baseline and at the end of the intervention. Serum and red blood cell folate concentrations increased significantly and serum homocysteine concentrations decreased significantly in the fortified food groups after the intervention. The proportions of folate deficiency decreased significantly in the fortified food groups. The variables of social cognitive theory including outcome expectations and behavioral capability score increased significantly in the nutrition education groups after the intervention. Our results suggest that folic acid‐fortified food is effective in improving folate nutritional status even after 4‐week supplementation, and nutrition education has a positive impact on the various factors related to behavior change.

Folate status and health: challenges and opportunities.

Each year approximately 2400 pregnancies develop folic acid-preventable spina bifida and anencephaly in Europe. Currently, 70% of all affected pregnancies are terminated after prenatal diagnosis. The prevalence of neural tube defects (NTDs) has been significantly lowered in more than 70 countries worldwide by applying fortification with folic acid. Periconceptional supplementation of folic acid also reduces the risk of congenital heart diseases, preterm birth, low birth weight, and health problems associated with child mortality and morbidity. All European governments failed to issue folic acid fortification of centrally processed and widely eaten foods in order to prevent NTDs and other unwanted birth outcomes. The estimated average dietary intake of folate in Germany is 200 μg dietary folate equivalents (DFE)/day. More than half of German women of reproductive age do not consume sufficient dietary folate to achieve optimal serum or red blood cell folate concentrations (>18 or 1000 nmol/L, respectively) necessary to prevent spina bifida and anencephaly. To date, targeted supplementation is recommended in Europe, but this approach failed to reduce the rate of NTDs during the last 10 years. Public health centers for prenatal care and fortification with folic acid in Europe are urgently needed. Only such an action will sufficiently improve folate status, prevent at least 50% of the NTD cases, reduce child mortality and morbidity, and alleviate other health problems associated with low folate such as anemia.

Folate status and intake of tribal Indian adolescents aged 10 to 17 years.

Adequate folate intake and levels are advisable throughout life but are of particular importance during adolescence, a period of rapid growth. However, folate insufficiency in economically deprived Indian adolescents is understudied. This cross-sectional study examined the prevalence of folate deficiency and adequacy of folate intake of 224 tribal Indian adolescents (10 to 17 years of age). The secondary aim was to study the association between anemia status and folate status. Radioimmunoassay, multiple-pass 24-hour dietary recall, and HemoCue were used to measure red blood cell (RBC) folate, folate intake, and anemia status, respectively. The geometric mean (95% CI) RBC folate concentration (nmol/L) was 360.2 (329.7 to 393.6), and the mean ± SD folate intake (μg/day) and hemoglobin level (g/L) were 159.9 ± 44.7 and 125.4 ± 13.0, respectively. Almost half of boys and girls aged 10 to 12 and 13 to 15 years and 66.7% of girls aged 16 to 17 years were deficient in RBCfolate (< 340 nmol/L). The mean ± SD folate intake (μg/day) of girls (139.4 ± 34.5) was lower than that of boys (173.8 ± 45.5) (p < .001). With respect to adequacy of folate intake, a greater proportion of girls in the age group of 13-15 years (78.5% vs 38.6%, p < 0.001) and 16-17 years (100.0% vs 76.9%, p = 0.04) had intakes below their Recommended Dietary Allowance (RDA). No association was observed between folate intake and RBC folate deficiency or between anemia status and RBC folate deficiency. Folate insufficiency was widespread in tribal Indian adolescents. There is an urgent need to develop culturally sensitive strategies for improvement.

Unmetabolized Folic Acid Is Detected in Nearly All Serum Samples from US Children, Adolescents, and Adults1–4

AbstractBackground: Serum total folate consists mainly of 5-methyltetrahydrofolate (5-methylTHF). Unmetabolized folic acid (UMFA) may occur in persons consuming folic acid–fortified foods or supplements.Objectives: We describe serum 5-methylTHF and UMFA concentrations in the US population ≥1 y of age by demographic variables and fasting time, stratified by folic acid–containing dietary supplement use. We also evaluate factors associated with UMFA concentrations >1 nmol/L.Methods: Serum samples from the cross-sectional NHANES 2007–2008 were measured for 5-methylTHF (n = 2734) and UMFA (n = 2707) by HPLC–tandem mass spectrometry.Results: In supplement users compared with nonusers, we found significantly higher geometric mean concentrations of 5-methylTHF (48.4 and 30.7 nmol/L, respectively) and UMFA (1.54 and 0.794 nmol/L, respectively). UMFA concentrations were detectable (>0.3 nmol/L) in >95% of supplement users and nonusers, regardless of demographic or fasting characteristics; concentrations differed significantly by age and fasting time, but not by sex and race-ethnicity, both in supplement users and nonusers. The prevalence of UMFA concentrations >1 nmol/L was 33.2% overall and 21.0% in fasting (≥8 h) adults (≥20 y of age). Using multiple logistic regression analysis, UMFA concentrations >1 nmol/L were associated with being older, non-Hispanic black, nonfasting (<8 h), having smaller body surface area, higher total folic acid intake (diet and supplements), and higher red blood cell folate concentrations. In fasting adults, a decrease in the mean daily alcohol consumption was also associated with increased odds of UMFA concentrations >1 nmol/L.Conclusions: UMFA detection was nearly ubiquitous, and concentrations >1 nmol/L were largely but not entirely explained by fasting status and by total folic acid intake from diet and supplements. These new UMFA data in US persons ≥1 y of age provide much-needed information on this vitamer in a fortified population with relatively high use of dietary supplements.

Impact of asphyxia on red blood cell folate concentration levels in newborns.

To determine whether red blood cell (RBC) folate concentration levels are correlated with the occurrence of neonatal asphyxia and to study the effects of gestational age, gender, and mode of delivery on RBC folate concentration levels in newborns. Asphyxia is one of the frequent causes of morbidity and mortality of newborns. Severe perinatal asphyxia can arise due to many factors. In a prospective study, the RBC folate concentrations were determined on day 1 of life in the whole group (n=181) of full-term (n=121) and preterm (n=60) newborns. Immunochemical analysis for the determination of folate in erythrocytes was performed. RBC folate concentration levels in asphyxiated newborns (n=16) were significantly decreased (median 974 ng/ml; p=0.023) in comparison with healthy newborns. On the other hand, the RBC folate concentration levels were significantly increased in preterm newborns (median 1,212 ng/ml; p=0.01) in comparison with full-term newborns (median 1,098 ng/ml). Higher RBC folate concentration levels were found in newborns which had been delivered by Caesarean section (median 1,188 ng/ml; p=0.02) compared to those born vaginally (median 1,098 ng/ml). Our results confirmed a significant decrease in RBC folate concentration in asphyxiated newborns on their first day of life (Fig. 4, Ref. 36).

Amount of folic acid in different types of nutrition used in the neonatal period.

Folic acid is one of the important supplements for adequate development during pregnancy. A higher intake of folic acid during pregnancy and lactation is recommended. In prospective study the group of premature newborns (n = 52) and the type of nutrition were observed. The red blood cell (RBC) folate concentration levels were determined in the first 24 hours after delivery, before and after oral treatment with folic acid (100 µg/day). Immunochemical analysis for the determination of folate in erythrocytes was performed. In the group of premature newborns the RBC folate concentration levels after treatment were significantly increased (p < 0.0001). A dynamic increase in the concentration levels of folates in erythrocytes before and after treatment was observed, in spite of the reciprocally decreasing blood count parameters, but without any statistically significant correlation. The infant nutrition before treatment contained significantly higher amount of folic acid in fortified breast milk compared to breast milk (p = 0.04). The various types of nutrition for preterm newborns contain a different amount of folic acid. It poses a question of real needs of these patients. The best way to determine the optimal whole amount of folate is to know the real levels of folate in premature newborns (Tab. 2, Fig. 5, Ref. 26). Text in PDF www.elis.sk.

Red blood cell folate concentrations in term newborns: recent findings in the Slovak Republic

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.

Scientific Opinion on Dietary Reference Values for folate

Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for folate. The Panel concludes that an Average Requirement (AR), as well as a Population Reference Intake (PRI) assuming a coefficient of variation (CV) of 15 % to account for the additional variability associated with the higher requirement for folate in individuals with the methylene-tetrahydrofolate reductase (MTHFR) 677TT genotype, can be derived from biomarkers of folate status. Several health outcomes possibly associated with folate intake/status were also considered, but data were found to be insufficient to establish DRVs. For adults, the AR is determined from the folate intake required to maintain folate adequacy characterised by serum and red blood cell folate concentrations of ≥ 10 and 340 nmol/L, respectively. An AR of 250 µg dietary folate equivalents (DFE)/day and a PRI of 330 µg DFE/day are derived. For infants aged 7–11 months, an Adequate Intake (AI) of 80 µg DFE/day is derived by extrapolating upwards from the estimated folate intake in exclusively breast-fed infants. For children, ARs are extrapolated from the AR for adults using allometric scaling and growth factors and considering differences in reference weights. PRIs ranging from 120 µg DFE/day for 1–3 year-old children to 330 µg DFE/day for boys and girls aged 15–17 years are derived. For pregnant women, an AI of 600 µg DFE/day is derived based on a study on maintenance of serum and red blood cell folate concentrations in pregnancy. For lactating women, an additional intake of 130 µg DFE/day is considered to cover folate losses via breast milk; this figure is added to the AR for non-lactating women and a PRI of 500 µg DFE/day is derived.

Outcome of a public consultation on the Draft Scientific Opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on Dietary Reference Values for folate

Outcome of a public consultation on the Draft Scientific Opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on Dietary Reference Values for folate

Folic Acid Fortification and Women’s Folate Levels in Selected Communities in Brazil - A First Look

Several countries have implemented mandatory folic acid fortification of wheat flour and selected grain products to increase the folate intake of reproductive-aged women. Brazil implemented a folic acid fortification program in 2004. No previous studies have examined folate differences among Brazilian women following the mandate. We evaluate differences in serum and red blood cell (RBC) folate concentrations between two samples of women of childbearing age from selective communities in Brazil, one tested before (N = 116) and the other after the mandate (N = 240). We compared the baseline folate levels of women enrolled in a prevention study shortly before the fortification mandate was implemented, to baseline levels of women from the same communities enrolled in the same study shortly after fortification began. The participants were women enrolled in a folate supplementation clinical trial, at a hospital specializing in treating craniofacial anomalies in the city of Bauru from January 29, 2004 to April 27, 2005. We only compared baseline folate levels before the women received oral cleft prevention program (OCPP) folic acid supplements. Women enrolled after the fortification mandate had higher means of serum folate (20.3 versus 11.2 nmol/L; p < 0.001) and RBC folate (368.3 versus 177.6 nmol/L; p < 0.001) than women enrolled before the mandate. Differences in folate levels between the two groups remained after adjusting for several co-variables. The results suggest that serum and RBC folate levels among women of childbearing age increased after implementing the folic acid fortification mandate in Brazil.

Population red blood cell folate concentrations for prevention of neural tube defects: bayesian model

Objective To determine an optimal population red blood cell (RBC) folate concentration for the prevention of neural tube birth defects.Design Bayesian model.Setting Data from two population based studies in China.Participants...

Socio-demographic and lifestyle factors associated with folate status among non-supplement-consuming Canadian women of childbearing age.

Mandatory folic acid fortification was implemented in Canada in 1998 to reduce the risk of neural tube defects (NTD). Our objective was to assess the relationship between socio-demographic factors and folate status in non-supplement-consuming Canadian women of childbearing age. Data on demographic factors, lifestyle factors, physical measures and red blood cell (RBC) folate concentration were collected from 1,008 non-supplement-consuming women aged 15-49 years in the Canadian Health Measures Survey (2007-2009). RBC folate ³906 nmol/L was used as a cut-off for optimal folate status for protection from NTD. Approximately 75% of non-supplement consuming women had an RBC folate concentration ³906 nmol/L. Young age (15-19 years), White ethnicity, less than secondary education, lowest income adequacy, smoking and high body mass index were associated with a higher prevalence of lower folate status. After adjustment, only young age (adjusted odds ratio [OR] 1.99-95% confidence interval [CI]: 1.25-3.18) was associated with lower folate status. Less than secondary education (adjusted OR 5.66, 95% CI: 1.10-29.04) and lowest income adequacy (adjusted OR 4.77, 95% CI: 1.06-21.49) were associated with lower folate status in women aged 15-24 and 25-49 years, respectively. Many risk factors for lower folate status identified before food fortification was implemented were not associated with folate status in our representative sample of non-supplement-consuming Canadian women. However, younger women, women aged 15-24 with less than secondary education and women aged 25-49 with low income adequacy remain at risk of lower folate status, supporting the continued promotion of folic acid supplement use to women of childbearing age.

Blood folate concentrations among women of childbearing age by race/ethnicity and acculturation, NHANES 2001‐2010 (130.5)

Objective: The objective of this research was to assess the differences in serum and red blood cell (RBC) folate concentrations between non‐Hispanic white (NHW) women and Mexican American (MA) women and among MA women by acculturation factors. Methods: Data from the 2001‐2010 NHANES were used to examine how blood folate concentrations differ among NHW or MA women of childbearing age, in general and stratified by folic acid containing supplement use. Women were considered supplement users if they reported any use of a folic acid containing supplement in the prior 30 days. Results: MA women with lower acculturation factors (i.e. those who reported primarily speaking Spanish, being born in Mexico, or living in the United States &lt; 15 years) had lower serum and RBC folate concentrations compared to NHW women and to their more acculturated MA counterparts. Consuming a folic acid containing supplement can decrease these disparities, but MA women, especially lower acculturated MA women, were less likely to report using supplements. Conclusions: Public health efforts to increase blood folate concentrations among MA women should consider acculturation factors when identifying appropriate interventions.

Assessing the association between the methylenetetrahydrofolate reductase (MTHFR) 677C→T polymorphism on blood folate concentrations: a systematic review and meta‐analysis of trials and observational studies (LB311)

Background: The methylenetetrahydrofolate reductase (MTHFR) 677C→T polymorphism is a risk factor for neural tube birth defects (NTDs). The T allele produces an enzyme with reduced folate processing capacity, which has been shown to produce lower blood folate concentrations in some studies.Objective: To assess the association between MTHFR C677T genotypes (CC, CT, TT) and blood folate concentrations among women aged 12‐49 years.Design: We conducted a systematic review of literature published between 1/1992‐7/2013 to identify controlled trials and observational studies that reported serum, plasma, or red blood cell (RBC) folate concentrations and MTHFR C677T genotype. We applied a Bayesian random‐effects model to predict differences in blood folate concentrations between MTHFR C677T genotypes, stratified by folate assay.Results: Thirty‐eight studies met criteria for inclusion. Serum/plasma folate concentrations showed a consistent genotype trend with the highest concentrations for CC (CC &gt; CT &gt; TT) regardless of assay type. RBC folate concentrations measured by microbiologic assay also demonstrated this trend; however, this trend was reversed (CC &lt; CT &lt; TT) in studies using protein‐binding assays.Conclusions: Meta‐analyses results showed blood folate concentrations differed by assay type and genotype. Previous evidence has shown that RBC folate concentrations measured with a radioimmunoassay requires adjustment for genotype‐dependent folate recovery; our results suggest that other protein‐binding assays could have similar limitations. Compared to CC individuals, TT individuals have lower blood folate concentrations, which may increase a woman’s risk for an NTD‐affected pregnancy.