Knowledge gaps in understanding the metabolic and clinical effects of excess folates/folic acid: a summary, and perspectives, from an NIH workshop

Associations of maternal serum folate, vitamin B12 and their imbalance with gestational diabetes mellitus: The mediation effects of the methionine cycle related metabolites

BACKGROUND & AIMS

Maternal high level of folate and low level of vitamin B12, namely "folate and vitamin B12 imbalance", has been found to be associated with metabolic disorders, such as gestational diabetes mellitus (GDM). The aims of this study were to explore the associations of maternal serum folate, vitamin B12 and their imbalance in early pregnancy with GDM, and to explore the potential mediation effects of the methionine cycle related metabolites on the above associations.

METHODS

This nested case-control study (172 GDM case-control pairs) was conducted based on a prospective birth cohort. Serum concentrations of 5-methyltetrahydrofolate (5-MTHF), vitamin B12 and methionine cycle related metabolites [S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and Homocysteine (Hcy)] were detected. 5-MTHF (nmol/L)/vitamin B12 (pmol/L) times 1000 was calculated to indicate the imbalance status of folate and vitamin B12. Conditional logistic regression was performed to analyze the associations of 5-MTHF, vitamin B12 and their imbalance with GDM. The mediation effect models were applied to explore the mechanism.

RESULTS

High serum level of 5-MTHF in early pregnancy was related to a higher risk of GDM (OR = 2.00, 95%CI: 1.19-3.37). Compared with the group of the lowest tertile concentration of vitamin B12, the group of the highest concentration had a lower risk of GDM (OR = 0.33, 95%CI: 0.11-0.97). Higher 5-MTHF/vitamin B12 was associated with a higher risk of GDM (OR = 1.67, 95%CI: 1.08-2.56). Besides, no significant mediation effect of methionine cycle related metabolites was found on the associations of folate, vitamin B12 and the imbalance status with the risk of GDM.

CONCLUSIONS

High maternal serum folate, low vitamin B12 levels and the resulting imbalance may increase the risk of GDM. The theory of "folate trap" could not explain the effect of folate, vitamin B12 and their imbalance on GDM.

Impact of Metformin Therapy on Vitamin B12 Levels in Patients With Type 2 Diabetes Mellitus

INTRODUCTION

Diabetes mellitus (DM) is a serious health condition affecting people worldwide with a high prevalence rate. DM is classified according to its aetiology into type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM); several risk factors contribute to the development of T2DM, such as age, genetic predisposition and obesity. Metformin is a proven drug of choice, and it is used as a first-line treatment for patients with T2DM to improve their glycaemic levels. Vitamin B12 is an important water-soluble vitamin, and its deficiency can lead to megaloblastic anaemia.

MATERIAL AND METHODS

A Cross-sectional retrospective study was conducted on patients with T2DM in a Sedi Hussein diabetic polyclinic in Benghazi, Libya. The total sample was 381 patients: T1DM 15 (n), and T2DM 366 (n). T1DM was excluded from our results. Patients with T2DM were divided into two groups: the control group (not on metformin) consisted of 71 patients, and the group that received metformin (M group) consisted of 295 patients.

AIMS OF THE STUDY

To assess serum vitamin B12 levels in patients with T2DM and evaluate the prevalence of vitamin B12 deficiency among those receiving metformin treatment.

RESULTS

The M group significantly decreased vitamin B12 serum levels by 443.56 mg/mL versus the control group of 541.33 pg/mL (p = 0.003). The prevalence of patients with vitamin B12 deficiency under the metformin treatment was 23.84%. There was no significant difference in correlation between serum vitamin B12 levels and both doses of metformin and the duration of diabetes mellitus.

CONCLUSION

Vitamin B12 was significantly decreased in patients with T2DM receiving metformin.

Folate from probiotic bacteria and its therapeutic applications

Folate, an essential water soluble vitamin B9 that cannot be synthesized naturally by the bodily function. Dietary sources or probiotic-folates are the two biological modes for acquiring the target vitamin which aids DNA synthesis and repair. Probiotics are known for their divergent health benefits and have garnered significant interest. Particularly in microbial strains that produce folate offers a promising way to enhance the level of folate. Notably, folate-producing probiotic strain includes Lactiplantibacillus, Lactococcus, Bifidobacterium, and Streptococcus. As an emerging source of health benefits, folate producing probiotics helps in improving the gut microbiota for overall well-being of human body. On the other side, chemically synthesized folic acid were not highly advantageous as they lacks absorption, conversion and excretion. Hence, usage of microbial-folate are safer as it can easily undergo absorption and reduces severe side effects. The present review mainly focus on folate one-carbon metabolism, its significance in human health, folate deficiency and malabsorption, adverse effects and folate synthesis from probiotic bacterial strains, and also toxicological impacts. In particular, the beneficiary role of these probiotic strains were found to be associated with therapeutic applications in several diseases such as autoimmune disorder, metabolic disorders, and cardiovascular diseases (CVDs), wound healing, drug delivery and cancer.

Age-specific associations of RBC folate and several serum folate forms with obesity risk: NHANES 2011-2018

Background

This study aims to explore the associations between RBC folate, several serum folate forms [serum total folate, 5-methyltetrahydrofolate (5-mTHF), and unmetabolized folic acid (UMFA)], and obesity risk in middle-aged and older populations.

Methods

Data from NHANES (2011-2018) included 11,615 participants. Generalized linear models (GLMs) were applied to investigate associations of RBC folate and various serum folate forms with obesity risk after multivariable adjustment. Potential effect modifications were examined through stratified analyses and multiplicative interaction testing.

Results

Among the total sample, middle-aged, and older participants, 4578 (39.4%), 3613 (40.0%), and 965 (37.2%) were obese, respectively. A positive association between RBC folate and obesity risk was observed, with the highest risks of obesity were consistently found in the fourth quartile (≥ 1,430 nmol/L) for the middle-aged adults (OR = 1.104, 95% CI: 1.045-1.166) and the older participants (OR = 1.157, 95% CI: 1.036-1.293). A significant negative association between serum total folate levels and obesity risk in middle-aged participants, with an OR of 0.804 (95% CI: 0.773-0.835) in the highest quartile (≥ 54.2 nmol/L). Similarly, serum 5-mTHF levels were negatively associated with obesity risk, with an OR of 0.800 (95% CI: 0.772-0.830) in the highest quartile (≥ 51.2 nmol/L). Most importantly, older participants with UMFA levels in the fourth quartile (≥ 1.06 nmol/L) had a higher risk of obesity (OR, 1.056; 95% CI: 1.004-1.110) compared with those with lower UMFA levels, but this association was not found in the total participants or the middle-aged participants.

Conclusion

Significant positive relationships exist between RBC folate and obesity risk. Additionally, low serum 5-mTHF in middle-aged participants and high UMFA in older adults were associated with increased obesity risk, highlighting the importance of monitoring folate concentrations for guiding future clinical trials on folate supplementation.

Folic acid supplementation in children with sickle cell disease: a randomized double-blind noninferiority cross-over trial

BACKGROUND

Children with sickle cell disease (SCD) in Canada are routinely supplemented with folic acid to provide sufficient folate for the increased demands of erythropoiesis. However, with the mandatory folic acid fortification of refined grains and pharmacotherapies that extend the lifespan of sickled red blood cells (RBC), this clinical practice is in question.

OBJECTIVES

This study aims to determine the efficacy of folic acid supplementation by measuring the effect of 12 ± 1 wk of 1 mg/d folic acid, compared with placebo, on concentrations of RBC folate (primary outcome), serum folate, and 1-carbon-related metabolites, and clinical outcomes in children with SCD.

METHODS

In this double-blind randomized controlled noninferiority cross-over trial, 31 children with SCD, aged 2-19 y, were enrolled and randomly assigned (1:1 with blocks of 4) to 1 mg/d folic acid, the current standard of care, or a placebo for 12 ± 1 wk. After a 12 ± 1 wk washout period, treatments were reversed.

RESULTS

The mean [95% confidence interval (CI)] difference in endline RBC folate concentrations across treatments was -179 (-260, -99) nmol/L, with the lower boundary of the CI exceeding noninferiority but the upper boundary not (P = 0.0001; modified intention-to-treat). There was no significant difference in the number of participants who had RBC folate deficiency after each treatment (P = 0.059). No participants presented with serum folate deficiency (<7 nmol/L). There were no significant differences observed in 1-carbon metabolite concentrations (total homocysteine, S-adenosylhomocysteine, S-adenosylmethionine, vitamin B12, or methylmalonic acid), hematological measures, nor clinical outcomes (specifically acute pain episodes or megaloblastic changes) when individuals were supplemented with folic acid in comparison with placebo.

CONCLUSIONS

Despite mandatory food fortification and advances in the medical treatment of SCD, it appears that some children with this condition may still benefit from daily folic acid supplementation. Whether this translates to improved clinical outcomes remains uncertain. This trial was registered at clinicaltrials.gov as NCT04011345 (https://clinicaltrials.gov/study/NCT04011345).

Maternal serum folate status during early pregnancy: Sex-specific association with neonatal adiposity

BACKGROUND & AIMS

Early pregnancy folate has been associated with GDM and possible adiposity in the newborn. The present study examined associations between maternal early pregnancy folate levels and sex-specific neonatal anthropometry. We further explored possible mediation by maternal glycemia on the association between folate and neonatal adiposity.

METHODS

Sub-group data (n = 511) from a UK multi-ethnic early pregnancy longitudinal study (micronutrients in Pregnancy as a Risk factor for gestational Diabetes and Effects on mother and baby; PRiDE) was used. Maternal serum folate was assessed during early pregnancy (Mean ± SD = 12.5 ± 1.6 gestational weeks) and infant anthropometry including skinfold thickness (SFT) and mid-upper arm circumference (MUAC) at birth. Multiple linear regression was performed to analyse the relationship between maternal folate and infant adiposity indices. Interaction analysis was used to identify maternal glucose mediation of this relationship.

RESULTS

Excess folate levels (≥45 nmol/l) were found in 40.3 % pregnant women (n = 206). Early pregnancy folate (1 SD unit) was positively associated with male newborn triceps SFT (std β = 0.17 (95 % CI: 0.06, 0.29; p < 0.05)) after adjusting for key maternal and infant confounders in multiple comparisons using Benjamini-Hochberg procedure. However, no associations were seen in female newborns. No influence of maternal fasting (FPG) and 2-h plasma glucose (2 h-PG) were detected on the association between folate and newborn anthropometry.

CONCLUSION

Our findings suggest a potential sex-specific influence of maternal folate on infant anthropometric indices. The association between early pregnancy folate on newborn adiposity was not mediated by maternal FPG and/or 2 h-PG at 24-28 weeks.

Prenatal Intake of High Multivitamins or Folic Acid With or Without Choline Contributes to Gut Microbiota-Associated Dysregulation of Serotonin in Offspring

The gut microbiota is amenable to early nutrition including micronutrients but intake above and below the recommendations commonly occur with unknown consequences. Serotonin (5-hydroxytryptamine [5-HT]) is a monoamine found centrally and peripherally with diverse functions such as food intake regulation via the hypothalamic 5-HT receptor 2C (5-HTR2C). This study determined the impact of prenatal micronutrients on the gut microbiota and serotonergic system in offspring. Pregnant Wistar rats were fed either recommended vitamins (RV), high vitamins (HV), high folic acid with recommended choline (HFRC), or high folic acid with no choline (HFNC). Offspring were fed a high-fat diet for 12 weeks postweaning. HV, HFRC, and HFNC males and females had lower hypothalamic 5-HTR2C protein expression compared to RV. Brain 5-HT concentrations were lower but colon 5-HT concentrations were higher in HV and HFNC males and females and HFRC males compared to RV. Refeeding response after 5-HTR2C agonist was negatively correlated with hypothalamic 5-HTR2C protein expression in males and with brain 5-HT concentrations in females. Random forest revealed top bacterial taxa, which Lactococcus, Ruminococcus, Bacteroides, and Oscillospira showed significant correlations with refeeding response and concentrations of brain and colon 5-HT. In conclusion, excess or imbalanced prenatal consumption of micronutrients leads to gut microbiota-associated disturbances in the serotonergic system in offspring.

Elevated red blood cell folate levels are associated with metabolic dysfunction-associated steatotic liver disease: results from NHANES 2017-2020

Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic liver disease worldwide. However, the role of folate in MASLD remains controversial. This study aimed to investigate the association between two folate indicators [serum folate and red blood cell (RBC) folate] and MASLD prevalence using data from the 2017-2020 National Health and Nutrition Examination Survey (NHANES).

Methods

A total of 3,879 participants without liver disease or significant alcohol consumption were included in the final analysis. Hepatic steatosis was assessed via transient elastography, with MASLD defined as a controlled attenuation parameter (CAP) ≥285 dB/m and the presence of at least one cardiometabolic risk factor. Logistic regression and generalized additive models (GAMs) were used to evaluate associations between folate levels and MASLD, with subgroup analyses stratified by age, gender, and body mass index (BMI).

Results

After full adjustment for confounders, RBC folate exhibited a significant positive association with MASLD (OR = 1.111 and 95% CI: 1.015-1.216 per 1-unit increase). In contrast, serum folate showed a transient negative association in minimally adjusted models (OR = 0.869 and 95% CI: 0.802-0.941), which disappeared after further adjustments. Subgroup analyses confirmed that age, gender, and BMI did not modify the RBC folate-MASLD relationship.

Discussion

These findings suggest that elevated RBC folate levels are independently associated with MASLD prevalence, whereas serum folate may lack clinical relevance due to susceptibility to confounding factors. RBC folate, as a stable biomarker of long-term folate status, may serve as a superior indicator for investigating folate-MASLD associations.

Biological, dietetic and pharmacological properties of vitamin B9

Humans must obtain vitamin B9 (folate) from plant-based diet. The sources as well as the effect of food processing are discussed in detail. Industrial production, fortification and biofortification, kinetics, and physiological role in humans are described. As folate deficiency leads to several pathological states, current opinions toward prevention through fortification are discussed. Claimed risks of increased folate intake are mentioned as well as analytical ways for measurement of folate.

Disrupted methionine cycle triggers muscle atrophy in cancer cachexia through epigenetic regulation of REDD1

The essential amino acid methionine plays a pivotal role in one-carbon metabolism, facilitating the production of S-adenosylmethionine (SAM), a critical supplier for DNA methylation and thereby a modulator of gene expression. Here, we report that the methionine cycle is disrupted in skeletal muscle during cancer cachexia, leading to endoplasmic reticulum stress and DNA hypomethylation-induced expression of the DNA damage inducible transcript 4 (Ddit4) gene, encoding the regulated in development and DNA damage response 1 (REDD1) protein. Targeting DNA methylation by depletion or pharmacological inhibition of DNA methyltransferase 3A (DNMT3A) exacerbates cachexia, while restoring DNMT3A expression or REDD1 knockout alleviates cancer cachexia-induced skeletal muscle atrophy in mice. Methionine supplementation restores DNA methylation of the Ddit4 promoter in a DNMT3A-dependent manner, thereby inhibiting activating transcription factor 4 (ATF4)-mediated Ddit4 transcription. Thus, with the identification of the methionine/SAM-DNMT3A/DNA hypomethylation-Ddit4/REDD1 axis, our study provides molecular insights into an epigenetic mechanism underlying cancer cachexia, and it suggests nutrient supplementation as a promising therapeutic strategy to prevent or reverse cachectic muscle atrophy.

Folate metabolism in myelofibrosis: a missing key?

Folates serve as key enzyme cofactors in several biological processes. Folic acid supplementation is a cornerstone practice but may have a "dark side". Indeed, the accumulation of circulating unmetabolized folic acid (UMFA) has been associated with various chronic inflammatory conditions, including cancer. Additionally, by engaging specific folate receptors, folates can directly stimulate cancer cells and modulate the expression of genes coding for pro-inflammatory and pro-fibrotic cytokines.This evidence could be extremely relevant for myelofibrosis (MF), a chronic myeloproliferative neoplasm typified by the unique combination of clonal proliferation, chronic inflammation, and progressive bone marrow fibrosis. Folate supplementation is frequently associated with conventional or investigational drugs in the treatment of MF-related anemia to tackle ineffective erythropoiesis. In this review, we cover the different aspects of folate metabolism entailed in the behavior and function of normal and malignant hematopoietic cells and discuss the potential implications on the biology of myelofibrosis.

Folic Acid and Methyltetrahydrofolate Supplementation in the Mthfr677C>T Mouse Model with Hepatic Steatosis

BACKGROUND/OBJECTIVES

The MTHFR677C>T gene variant results in a thermolabile MTHFR enzyme associated with elevated plasma homocysteine in TT individuals. Health risks associated with the TT genotype may be modified by dietary and supplemental folate intake. Supplementation with methyltetrahydrofolate (methylTHF) may be preferable to folic acid because it is the MTHFR product, and does not require reduction by DHFR to enter one-carbon folate metabolism. In the Mthfr677C>T mouse model for this variant, female 677TT (TT) mice have an increased incidence of hepatic steatosis. The objective of this study was to compare the effects of methylTHF and folic acid supplementation on hepatic steatosis and one-carbon metabolism in this model.

METHODS

Male and female C57BL/6J 677CC (CC) and TT mice were fed control (CD), 5xmethylTHF-supplemented (MFSD), or 5xfolic-acid-supplemented (FASD) diets for 4 months. Liver sections were assessed for steatosis by Oil Red O staining. One-carbon metabolites were measured in the liver and plasma. MTHFR protein expression was evaluated in the liver.

RESULTS

MFSD had no significant effect on plasma homocysteine, liver SAM/SAH ratios, or hepatic steatosis in males or females as compared to CD. MTHFR protein increased in MFSD TT female liver, but remained <50% of the CC. FASD had no effect on plasma homocysteine but it decreased the liver MTHFR protein and SAM/SAH ratios, and increased hepatic steatosis in CC females.

CONCLUSIONS

MethylTHF and folic acid supplementation had limited benefits for TT mice, while folic acid supplementation had negative effects on CC females. Further investigation is required to determine if these effects are relevant in humans.

Maternal folic acid over-supplementation impairs cardiac function in mice offspring by inhibiting SOD1 expression

AIMS

Folic acid (FA) supplementation during pregnancy aims to protect foetal development. However, maternal over-supplementation of FA has been demonstrated to cause metabolic dysfunction and increase the risk of autism, retinoblastoma, and respiratory illness in the offspring. Moreover, FA supplementation reduces the risk of congenital heart disease. However, little is known about its possible adverse effects on cardiac health resulting from maternal over-supplementation. In this study, we assessed the detrimental effects of maternal FA over-supplementation on the cardiac health of the offspring.

METHODS AND RESULTS

Eight-week-old C57BL/6J pregnant mice were randomly divided into control and over-supplemented groups. The offspring cardiac function was assessed using echocardiography. Cardiac fibrosis was assessed in the left ventricular myocardium by histological analysis. Proteomic, protein, RNA, and DNA methylation analyses were performed by liquid chromatography-tandem mass spectrometry, western blotting, real-time quantitative PCR, and bisulfite sequencing, respectively. We found that maternal periconceptional FA over-supplementation impaired cardiac function with the decreased left ventricular ejection fraction in the offspring. Biochemical indices and tissue staining further confirmed impaired cardiac function in offspring caused by maternal FA over-supplementation. The combined proteomic, RNA expression, and DNA methylation analyses suggested that key genes involved in cardiac function were inhibited at the transcriptional level possibly due to increased DNA methylation. Among these, superoxide dismutase 1 was down-regulated, and reactive oxygen species (ROS) levels increased in the mouse heart. Inhibition of ROS generation using the antioxidant N-acetylcysteine rescued the impaired cardiac function resulting from maternal FA over-supplementation.

CONCLUSIONS

Our study revealed that over-supplementation with FA during mouse pregnancy is detrimental to cardiac function with the decreased left ventricular ejection fraction in the offspring and provides insights into the mechanisms underlying the association between maternal FA status and health outcomes in the offspring.

Folate prevents the autism-related phenotype caused by developmental pyrethroid exposure in prairie voles

Neurodevelopmental disorders (NDDs) have dramatically increased in prevalence to an alarming one in six children, and yet both causes and preventions remain elusive. Recent human epidemiology and animal studies have implicated developmental exposure to pyrethroid pesticides, one of the most common classes of pesticides in the US, as an environmental risk factor for autism and neurodevelopmental disorders. Our previous research has shown that low-dose chronic developmental pyrethroid exposure (DPE) changes folate metabolites in the adult mouse brain. We hypothesize that DPE acts directly on molecular targets in the folate metabolism pathway, and that high-dose maternal folate supplementation can prevent or reduce the biobehavioral effects of DPE. We exposed pregnant prairie vole dams chronically to vehicle or low-dose deltamethrin (3 mg/kg/3 days) with or without high-dose folate supplementation (methylfolate, 5 mg/kg/3 days). The resulting DPE offspring showed broad deficits in five behavioral domains relevant to neurodevelopmental disorders (including the social domain); increased plasma folate concentrations; and increased neural expression of SHMT1, a folate cycle enzyme. Maternal folate supplementation prevented most of the behavioral phenotypes (except for repetitive behaviors) and caused potentially compensatory changes in neural expression of FOLR1 and MTHFR, two folate-related proteins. We conclude that DPE causes neurodevelopmental disorder-relevant behavioral deficits; DPE directly alters aspects of folate metabolism; and preventative interventions targeting folate metabolism are effective in reducing, but not eliminating, the behavioral effects of DPE.

Excess Folic Acid Exposure Increases Uracil Misincorporation into DNA in a Tissue-Specific Manner in a Mouse Model of Reduced Methionine Synthase Expression

BACKGROUND

Folate and vitamin B12 (B12) are cofactors in folate-mediated 1-carbon metabolism (FOCM), a metabolic network that supports synthesis of nucleotides (including thymidylate [dTMP]) and methionine. FOCM impairments such as a deficiency or imbalance of cofactors can perturb dTMP synthesis, causing uracil misincorporation into DNA.

OBJECTIVE

The purpose of this study was to determine how reduced expression of the B12-dependent enzyme methionine synthase (MTR) and excess dietary folic acid interact to affect folate distribution and markers of genome stability in mouse tissues.

METHODS

Heterozygous Mtr knockout mice (Mtr+/-) model the FOCM-specific effects of B12 deficiency. Folate accumulation and vitamer distribution, genomic uracil concentrations, and phosphorylated histone H2AX (γH2AX) immunostaining were measured in male Mtr+/+ and Mtr+/- mice weaned to either a folate-sufficient control (C) diet (2 mg/kg folic acid) or a high folic acid (HFA) diet (20 mg/kg folic acid) for 7 wk.

RESULTS

Exposure to the HFA diet led to tissue-specific patterns of folate accumulation, with plasma, colon, kidney, and skeletal muscle exhibiting increased folate concentrations compared with control. Liver total folate did not differ. Although unmetabolized folic acid (UMFA) increased 10-fold in mouse plasma with HFA diet, UMFA accounted for <0.2% of total folate in liver and colon tissue. Exposure to HFA diet resulted in a shift in folate distribution in colon tissue with higher 5-methyl-THF and lower formyl-THF than in control mice. Mtr heterozygosity did not impact folate accumulation or distribution in any tissue. Mice on HFA diet exhibited higher uracil in genomic DNA and γH2AX foci in colon. Similar differences were not seen in liver.

CONCLUSIONS

This study demonstrates that folic acid, even when consumed at high doses, does not meaningfully accumulate in mouse tissues, although high-dose folic acid shifts folate distribution and increases uracil accumulation in genomic DNA in colon tissue.

Supplementation practices among pregnant women and those trying to conceive: a population-representative survey in Vancouver, Canada

Dietary supplements including vitamins, minerals, and natural health products are commonly consumed by those aiming to optimize fertility and pregnancy outcomes. The aim of this survey was to describe supplementation practices among individuals who were pregnant or trying to conceive in Vancouver, Canada. An online survey was conducted among 500 individuals who were pregnant (n = 250) or trying to conceive (n = 250). Participants met a substantial proportion of vitamin and mineral recommendations through supplements alone. Exceptions included calcium, magnesium, and choline, with median (interquartile range (IQR)) supplementation doses reported by those who were pregnant and trying to conceive, respectively, of: 250 (200 and 250 mg) and 250 (200 and 250 mg), 50 (50 and 75 mg) and 50 (50 and 90 mg), and 53 (10 and 150 mg) and 55 (10 and 100 mg), as compared to perinatal recommendations of 1000 mg/day (calcium), 350 mg/day (magnesium), and 450 mg/day (choline). Conversely, median (IQR) doses of folate reported by those who were pregnant and trying to conceive, respectively, were: 1000 (780 and 1000 µg) and 1000 (800 and 1000 µg), with ∼70% overall (337/471) reporting doses ≥1000 µg (the tolerable upper intake level). Most participants (451/500; 90%) reported supplementation with a prenatal multivitamin; of these, 83% reported that supplementation occurred daily. Overall, as diet was not considered, we cannot ascertain whether recommendations for calcium, magnesium, and choline were met through the combination of supplements and foods; however, we believe that additional supplementation with choline may be required to meet recommendations in pregnancy. Excessive folate supplementation has been previously identified as a concern throughout North America; here, we provide further evidence for excessively high doses consumed via supplements.

One-carbon metabolism shapes T cell immunity in cancer

One-carbon metabolism (1CM), comprising folate metabolism and methionine metabolism, serves as an important mechanism for cellular energy provision and the production of vital signaling molecules, including single-carbon moieties. Its regulation is instrumental in sustaining the proliferation of cancer cells and facilitating metastasis; in addition, recent research has shed light on its impact on the efficacy of T cell-mediated immunotherapy. In this review, we consolidate current insights into how 1CM affects T cell activation, differentiation, and functionality. Furthermore, we delve into the strategies for modulating 1CM in both T cells and tumor cells to enhance the efficacy of adoptively transferred T cells, overcome metabolic challenges in the tumor microenvironment (TME), and maximize the benefits of T cell-mediated immunotherapy.

Protocol for a community-based, household-randomised, dose-response trial to assess the acceptability, nutritional effects and safety of double-fortified salt containing iodine and folic acid compared with iodised salt among non-pregnant Ethiopian women of reproductive age (DFS-IoFA)

INTRODUCTION

The prevalence of neural tube defects (NTDs) is higher in Ethiopia than most other countries, and ~84% of Ethiopian women of reproductive age (WRA) have folate insufficiency, a major risk factor for NTDs. Salt fortification with folic acid is a potential strategy to improve women's folate status, but data are needed on the acceptability, nutritional impact and safety of folic acid fortification of iodised salt.

METHODS AND ANALYSIS

The study is designed as a community-based, household-randomised, dose-response trial. A total of 360 non-pregnant WRA 18-49 years of age will be randomly assigned to one of three intervention arms: (1) iodised salt fortified with 30 ppm folic acid to provide ~200 µg folic acid/day; (2) iodised salt fortified with 90 ppm folic acid to provide ~600 µg folic acid/day; or (3) iodised salt (comparator). The preweighed salts will be delivered to participants' homes biweekly for 26 weeks; unused salt will be collected and weighed. Fasting, venous blood samples will be collected at baseline, end line and a randomly assigned intermediate time point for assessment of folate, iodine, vitamin B12 and other micronutrient status biomarkers. Women's dietary intakes, including discretionary salt consumption, will be measured using weighed food records; 24-hour urine specimens will be analysed for sodium and iodine excretion. Primary outcomes are women's consumption of study salts, change in biomarkers of folate and iodine status and prevalence of adverse events. Results will be analysed using analysis of covariance models to estimate group mean differences for continuous outcomes, controlling for baseline measurements, and log-binomial or modified Poisson regressions for categorical outcomes. Prespecified effect modifications will be explored.

ETHICS AND DISSEMINATION

The study has been approved by the Ethiopian Public Health Institute's Institutional Review Board, and the protocol has been registered with ClinicalTrials.gov (registration number NCT06223854). Study results will be published in open access scientific journals and disseminated nationally in Ethiopia.

TRIAL REGISTRATION NUMBER

NCT06223854.

Maternal Serum Folate During Pregnancy and Congenital Heart Disease in Offspring

Importance

The association of folate supplementation with congenital heart disease (CHD) prevention is controversial.

Objective

To examine the association of maternal serum folate levels at early to midpregnancy with CHD risk in offspring.

Design, Setting, and Participants

This case-control study recruited participants from one of China's largest cardiac referral centers between 2015 and 2018. CHD cases and non-CHD controls were matched according to maternal age at a ratio of 1:4. Data were analyzed from May to August 2023.

Exposures

Maternal serum levels of folate, vitamin B12, and homocysteine were measured around the gestational age of 16 weeks.

Main Outcomes and Measures

The primary outcome was CHD, which was confirmed using echocardiography. The association between CHD risk in offspring with maternal folate levels was measured using adjusted odds ratios (aORs) with 95% CIs in conditional logistic regression analyses. Interactions between folate, vitamin B12, and homocysteine and CHD were estimated on a multiplicative scale.

Results

A total of 129 CHD cases with ventricular septal defect as the most common phenotype and 516 matched controls were included. The mean (SD) maternal age at pregnancy was 31.6 (5.3) years. There was a U-shaped association between maternal serum folate levels at early to midpregnancy and CHD risk in offspring. Compared with the offspring in the second and third quartiles of maternal folate, those in the lowest (aOR, 3.09; 95% CI, 1.88-5.08) and highest quartiles (OR, 1.81; 95% CI, 1.07-3.06) had increased odds of CHD. The ORs were higher when applying the World Health Organization criteria to determine the normal range for serum folate levels. Interaction analyses suggested that the adverse associations between low and high maternal folate and CHD risk might be further magnified by vitamin B12 deficiency or elevated homocysteine.

Conclusions and relevance

In this case-control study of CHD, low maternal serum folate levels in early to midpregnancy were associated with an increased CHD risk in offspring, and excessively high folate levels were also associated with an elevated CHD risk. Further investigation is needed to make causal inferences for the observed associations and elucidate the underlying mechanisms.

The causal relationship between hydatidiform mole and nutrients: A two-sample Mendelian randomization study

BACKGROUND

Hydatidiform mole (HM), a subset of gestational trophoblastic disease, is considered precancerous and exhibits geographical variation. The incidence of HM is linked to nutritional factors. This study aimed to investigate the causal relationship between nutrients and HM using a bidirectional two-sample Mendelian randomization (MR) approach.

METHODS

We utilized publicly available genome-wide association study data to assess the causal associations between levels of specific vitamins (retinol, vitamins B12, B6, C, D, E, folate, and carotene) and minerals (iron, calcium, and magnesium) with HM. The MR analysis was conducted and reported following the STROBE-MR guidelines, employing MR Egger and inverse variance weighted (IVW) methods to estimate associations, with MR-PRESSO for pleiotropy testing.

RESULTS

The study revealed vitamin B6 as a significant protective factor against HM (MR-Egger OR: 0.094, 95 % CI: 0.011-0.0778, P < 0.05; IVW OR: 0.365, 95 % CI: 0.142-0.936, P < 0.05). Folate and magnesium showed suggestive associations with HM, whereas most other nutrients did not exhibit a causal relationship. MR-PRESSO analysis supported the absence of horizontal pleiotropy of vitamin B6. Besides, reverse MR analysis did not reveal a significant causal association between HM and serum nutrient levels, suggesting that differences of nutrients in HM patients may not be directly attributed to the mole.

CONCLUSION

This MR study provides evidence that vitamin B6 may protect against HM, and suggests potential roles for folate and magnesium in HM development, while highlighting the need for further research to confirm these findings.

Supplementation with Folic Acid or 5-Methyltetrahydrofolate and Prevention of Neural Tube Defects: An Evidence-Based Narrative Review

Background: Folic acid (FA), which in its chemical form is pteroylglutamic acid, is the fully oxidised, water-soluble, monoglutamic form of vitamin B9. This compound is part of the folate group but with higher bioavailability, and it is found in vitamin supplements and fortified foods and drugs. Folate metabolism is complex and associated with various metabolic pathways, all of which confer protection on the cell and allow its survival. Methods: We conducted a non-systematic search of articles published in English and Spanish including controlled trials, cohort studies, systematic re-views, and meta-analyses were included, as well as key studies in animal models related to pharmacokinetic studies. Search terms encompassed: "folic acid", "folates", "5-metyltetrahydrofolate", "5-MTHF", "neural tube defects", "supplementation", "fortification", AND "homocysteine" Results: A crucial role demonstrated for FA is to help prevent neural tube defects (NTDs). However, more studies are definitely still needed to establish 5-MTHF as a safe and effective therapeutic approach comparable with FA. Moreover, there is a lack of clinical studies that evaluate the efficacy of 5-MTHF supplementation in the prevention of NTDs. The present evidence-based narrative review discusses differences between FA and 5-MTHF in terms of structure, metabolism, bioavailability, clinical efficacy, and safety. Conclusions: Despite the potential value of 5-MTHF as an alternative to FA, clinical studies would be urgently needed to support the efficacy, dosage, timing, and/or safety of its use as a supplement.

Folate and synthetic folic acid content in Canadian fortified foods two decades after mandatory fortification

In 1998, Health Canada mandated folic acid fortification of white flour and enriched grain products to prevent neural tube defects. At the time, neither the Canadian Nutrient File (CNF) nor product labels reflected the actual folate content of foods. We aimed to assess if 20 years post-fortification, the CNF values for total folate and synthetic folic acid accurately reflect amounts determined by direct analysis. Using the 2001 Food Expenditure Survey and ACNielsen Company data, we identified 10-15 of the most purchased fortified foods across seven food categories in Canada. Total folate concentrations were determined by tri-enzyme digestion and microbial assay. Folic acid concentrations were determined using liquid chromatography-tandem mass spectrometry. Except for "cooked pastas", mean total folate content of foods (n = 89) were significantly higher than CNF values across categories (p < 0.05), reflecting 167% ± 54% of CNF values. Similarly, mean folic acid content of foods was higher than CNF values for all categories except "cooked pastas" (p < 0.05), with a mean of 188% ± 94% of CNF values; the latter CNF values included uncooked pasta. In sum, 20 years post-fortification, and 10 years since the last direct measurement, CNF and product label values still underestimate actual total folate and the folic acid content of foods. These findings emphasize that dietary estimates established using the CNF may significantly underestimate actual intakes and thus caution should be exercised when interpreting estimates of nutritional adequacy based on these values.

The role of l-leucovorin uptake and metabolism in the modulation of 5-fluorouracil efficacy and antifolate toxicity

Background

L-Leucovorin (l-LV; 5-formyltetrahydrofolate, folinic acid) is a precursor for 5,10-methylenetetrahydrofolate (5,10-CH2-THF), which is important for the potentiation of the antitumor activity of 5-fluorouracil (5FU). LV is also used to rescue antifolate toxicity. LV is commonly administered as a racemic mixture of its l-LV and d-LV stereoisomers. We compared dl-LV with l-LV and investigated whether d-LV would interfere with the activity of l-LV.

Methods

Using radioactive substrates, we characterized the transport properties of l-LV and d-LV, and compared the efficacy of l-LV with d-LV to potentiate 5FU-mediated thymidylate synthase (TS) inhibition. Using proliferation assays, we investigated their potential to protect cancer cells from cytotoxicity of the antifolates methotrexate, pemetrexed (Alimta), raltitrexed (Tomudex) and pralatrexate (Folotyn).

Results

l-LV displayed an 8-fold and 3.5-fold higher substrate affinity than d-LV for the reduced folate carrier (RFC/SLC19A1) and proton coupled folate transporter (PCFT/SLC46A1), respectively. In selected colon cancer cell lines, the greatest enhanced efficacy of 5FU was observed for l-LV (2-fold) followed by the racemic mixture, whereas d-LV was ineffective. The cytotoxicity of antifolates in lymphoma and various solid tumor cell lines could be protected very efficiently by l-LV but not by d-LV. This protective effect of l-LV was dependent on cellular RFC expression as corroborated in RFC/PCFT-knockout and RFC/PCFT-transfected cells. Assessment of TS activity in situ showed that TS inhibition by 5FU could be enhanced by l-LV and dl-LV and only partially by d-LV. However, protection from inhibition by various antifolates was solely achieved by l-LV and dl-LV.

Conclusion

In general l-LV acts similar to the dl-LV formulations, however disparate effects were observed when d-LV and l-LV were used in combination, conceivably by d-LV affecting (anti)folate transport and intracellular metabolism.

Distribution and correlates of plasma folate, vitamin B12, and homocysteine in a sample of low-income minority children aged 6 months to 9 years in the U.S

Background

Precision nutrition emphasizes tailoring dietary requirements across populations and life stages. Optimal folate and vitamin B12 levels are important for normal growth and development, but data are lacking for low-income minority U.S. children during early life periods. This study aimed to describe folate, vitamin B12, homocysteine (Hcy) levels, and influencing factors to address the gaps.

Methods

Blood samples from children aged 6 months to 9 years and mothers 48-72 hours postpartum in the Boston Birth Cohort (BBC) were tested for folate, vitamin B12, and Hcy. Maternal and child characteristics, sociodemographic factors, and feeding status were obtained from a standard maternal questionnaire interview at the enrollment and follow-up, and medical records. The distribution of children's folate, vitamin B12, and Hcy were described and factors influencing these biomarkers were analyzed.

Results

A wide distribution of folate, vitamin B12, and Hcy levels was observed in this sample, with longitudinal trends consistent with National Health and Nutrition Examination Survey (NHANES) data. Multivariate analysis showed that very preterm birth correlated with higher folate levels (adjusted β 4.236; 95% CI: 1.218, 7.253; p=0.006). Children aged 1-2 years and 3-8 years had lower folate levels compared to those <1 year (adjusted β -10.191 and -7.499 respectively; p<0.001). Vitamin B12 levels were higher in Black children (adjusted fold change 1.139; 95% CI: 1.052, 1.233; p=0.001) and those children whose mothers' B12 levels were at the highest quartile (Q4) (adjusted fold change 1.229; 95% CI: 1.094, 1.380; p=0.001). Delayed solid food introduction (> 6 months) correlated with lower children's B12 levels (adjusted fold change 0.888; 95% CI: 0.809, 0.975; p=0.013). Hcy levels were lower in Black children (adjusted fold change 0.962; 95% CI: 0.932, 0.993; p=0.018), higher in children with maternal Hcy levels in Q4 (adjusted fold change 1.081; 95% CI: 1.03, 1.135; p=0.002) and in children aged 3-8 years (adjusted fold change 1.084; 95% CI: 1.040, 1.131; p< 0.001).

Conclusions

This study revealed wide variations in plasma folate, vitamin B12, and Hcy levels among low-income minority U.S. children and identified race, maternal levels, child's age, prematurity, and timing of solid food introduction as significant correlates.

Association of serum folic acid levels in response to fasting blood glucose in early pregnancy with the risk of gestational diabetes mellitus: A retrospective cohort study

OBJECTIVE

With increasingly prevalent folic acid consumption in early pregnancy, concerns about its potentially negative effect on maternal metabolism have been raised. Recent findings regarding folic acid levels in the first trimester and the risk of gestational diabetes mellitus have been inconclusive. The aim of this study was to investigate the association of folic acid status in early pregnancy with gestational diabetes mellitus as well as examine whether glucose levels can be modulated by folic acid status during the same first trimester.

METHODS

This was a retrospective cohort study based on 27 128 Chinese pregnant women who registered during their first prenatal visit from January 2015 to December 2019. Serum folic acid and fasting blood glucose concentrations were measured during the 9th to 13th gestational weeks. Binary logistic regression was applied to estimate the odds ratios of gestational diabetes mellitus by using the serum folic acid levels quartiles with adjustment for major confounders. To investigate the potential effect of modifying key risk factors for gestational diabetes mellitus, we established subgroups, in which analyses were stratified by age (<25, 25-29, 30-34, and ≥35 y), parity (nulliparous and parous), prepregnancy body mass index (< 18.5, 18.5-23.9, and ≥ 24 kg/m2), and family history of diabetes (yes and no).

RESULTS

The positive association between maternal folate concentrations and fasting blood glucose was observed: the risk for hyperglycemia was higher in those in the middle (Q3) and higher (Q4) quartiles compared with those in Q1 and Q2. A higher risk for gestational diabetes mellitus was found in hyperglycemia of early pregnant women with high folate concentrations (Q3: odds ratio = 5.63; 95% CI, 4.56-6.95, and Q4: odds ratio = 5.57; 95% CI, 4.68-6.64) compared with normal fasting glucose mothers with folate concentrations in Q1 and Q2 after accounting for multiple covariables. Similar patterns were observed for different subgroups. Restricted cubic spline plots had a positive correlation of serum folic acid level with fasting blood glucose concentration as well as risk of gestational diabetes mellitus in a nonlinear pattern, with 32.5 nmol/L as the cutoff point for folic acid level.

CONCLUSIONS

Our findings underscore the importance of maintaining an appropriate folic acid concentration for preserving a lower risk of gestational diabetes mellitus, especially in women with relatively higher blood glucose in early pregnancy. Additionally, folic acid concentration > 32.5 nmol/L may be considered a risk factor for gestational diabetes mellitus. This research suggested that folic acid levels should be monitored during the first trimester from the first prenatal checkup to prevent adverse effects of excessive folic acid intake.

The Need for an Alternative Health Claim Process for Foods Based on Both Nutrient and Contaminant Profiles

Most authorized health claims on foods have been established on the basis of single dietary components, mainly micronutrients, such as vitamins, minerals, and possibly bioactives. Failure to sufficiently define and characterize the nutritional profile of a food product is one of the main reasons for rejection or incomplete status for thousands of health claim applications, whereas the food's contaminant profile is simply not accounted for. The objective of this work was to highlight the accumulating scientific evidence supporting a reform of the health claim evaluation process for foods toward more holistic approaches. This would entail the characterization of multiple nutrient-contaminant pairs and contaminant mixture profiles at contaminant levels currently considered "safe," including their interactions that would impact human health outcome(s) in a net positive or negative direction. The notion of a stable nutritional profile in food commodities has been challenged by studies reporting a variable food contaminant content and a declining content of proteins/micronutrients in crops due to anthropogenic greenhouse gas emissions. A holistic approach in the health claim process for foods would entail the incorporation of cumulative risk assessment and/or risk-benefit protocols that effectively combine health risks and benefits associated with multiple nutritional and contaminant attributes of the food/diet under evaluation.

Human milk oligosaccharide composition following supplementation with folic acid vs (6S)-5-methyltetrahydrofolic acid during pregnancy and mediation by human milk folate forms

Supplementation with folic acid versus (6S)-5-methyltetrahydrofolic acid (5-MTHF) results in different folate forms in human milk, with folic acid increasing unmetabolized folic acid (UMFA) at the expense of reduced folate forms. It is unknown whether folate forms present in human milk have further effects on human milk composition, such as human milk oligosaccharide (HMO) concentrations. We randomized 60 pregnant women in Canada to 0.6 mg/day folic acid or (6S)-5-MTHF. Human milk folate forms (LC-MS/MS) and nineteen HMOs (HPLC) were quantified at 1 week postpartum. Linear regression and causal mediation analysis were used to evaluate the effect of folate supplementation on HMO concentrations, and possible mediation by concentrations of UMFA and reduced folate forms in human milk (controlling for secretor status and parity). HMO concentrations were not different between groups, with no evidence of mediation by reduced folate forms; however, increased UMFA was associated with reduced concentrations of total HMOs and 3'-sialyllactose.

Maternal folic acid supplementation does not impact skeletal muscle function and metabolism in male and female CD-1 mouse offspring

Folic acid fortification of all white flour, enriched pasta, and cornmeal products became mandatory in Canada to reduce risk of neural tube defects at birth. Furthermore, Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend women take daily prenatal folic acid supplements in addition to folic acid fortified foods during pregnancy. However, the influence of maternal folic acid supplementation on offspring development, specifically the highly abundant and metabolically active skeletal muscle, is currently unknown. Thus, the purpose of this study was to determine the effect of supplemental folic acid (four times higher than normal dietary consumption), in utero and throughout suckling on muscle size, function, and metabolism in male and female CD-1 mouse offspring. The major findings were that maternal exposure to supplemental folic acid (i) had no impact on postpartum growth rates or muscle mass in female and male offspring, (ii) had no impact on skeletal muscle contractile kinetics in females and male offspring, and (iii) increased maximal phosphofructokinase activity in extensor digitorum longus of female and male offspring. These findings suggest that exposure to folic acid supplementation in utero and throughout suckling at levels four times higher than recommended had minimal effect on skeletal muscle size, function, and metabolism regardless of sex. Future research is needed explore the underlying biological pathways and mechanisms affected by folic acid supplementation during pregnancy and lactation on offspring skeletal muscle tissue, specifically in humans.

Low-dose daily folic acid (400 μg) supplementation does not affect regulation of folate transporters found present throughout the terminal ileum and colon of humans: a randomized clinical trial

BACKGROUND

Folic acid supplementation during the periconceptional period reduces the risk of neural tube defects in infants, but concern over chronic folic acid exposure remains. An improved understanding of folate absorption may clarify potential risks. Folate transporters have been characterized in the small intestine, but less so in the colon of healthy, free-living humans. The impact of folic acid fortification or supplementation on regulation of these transporters along the intestinal tract is unknown.

OBJECTIVE

The objective was to characterize expression of folate transporters/receptor (FT/R) and folate hydrolase, glutamate carboxypeptidase II (GCPII), from the terminal ileum and throughout the colon of adults and assess the impact of supplemental folic acid.

METHODS

In this 16-wk open-labeled randomized clinical trial, adults consumed a low folic acid-containing diet, a folate-free multivitamin, and either a 400 μg folic acid supplement or no folic acid supplement. Dietary intakes and blood were assessed at baseline, 8 wk, and 16 wk (time of colonoscopy). Messenger RNA (mRNA) expression and protein expression of FT/R and GCPII were assessed in the terminal ileum, cecum, and ascending and descending colon.

RESULTS

Among 24 randomly assigned subjects, no differences in dietary folate intake or blood folate were observed at baseline. Mean ± SD red blood cell folate at 16 wk was 1765 ± 426 and 911 ± 242 nmol/L in the 400 and 0 μg folic acid group, respectively (P < 0.0001). Reduced folate carrier, proton-coupled folate transporter, and folate-receptor alpha expression were detected in the terminal ileum and colon, as were efflux transporters of breast cancer resistance protein and multidrug resistance protein-3. Other than a higher mRNA expression of FR-alpha and GCPII in the 400 μg supplement group in the ascending colon, no treatment differences were observed (P < 0.02).

CONCLUSIONS

Folate transporters are present throughout the terminal ileum and colon; there is little evidence that a low dose of folic acid supplementation affects colonic absorption. This trial was registered at clinicaltrials.gov as NCT03421483.

Intake and biomarkers of folate and folic acid as determinants of chemotherapy-induced toxicities in patients with colorectal cancer: a cohort study

BACKGROUND

Capecitabine is an oral chemotherapeutic drug showing antitumor activity through inhibition of thymidylate synthase, an enzyme involved in folate metabolism. There are concerns about the high intake of certain vitamins, and specifically folate, during chemotherapy with capecitabine. Whether folate or folic acid, the synthetic variant of the vitamin, impact treatment toxicity remains unclear.

OBJECTIVE

We studied associations between intake and biomarkers of folate as well as folic acid and toxicities in patients with colorectal cancer (CRC) receiving capecitabine.

METHODS

Within the prospective COLON (Colorectal cancer: Longitudinal, Observational study on Nutritional and lifestyle factors that influence recurrence, survival, and quality of life) cohort, 290 patients with stage II to III CRC receiving capecitabine were identified. Dietary and supplemental intake of folate and folic acid were assessed at diagnosis and during chemotherapy using questionnaires (available for 280 patients). Plasma folate and folic acid levels were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) and were available for 212 patients. Toxicities were defined as toxicity-related modifications of treatment, including dose reductions, regimen switches, and early discontinuation. Associations of intake and biomarkers of folate and folic acid with toxicities were determined using Cox proportional hazards regression adjusted for age and sex.

RESULTS

In total, 153 (53%) patients experienced toxicities leading to modification of capecitabine treatment. Folate intake and plasma folate levels were not associated with risk of toxicities. However, use of folic acid-containing supplements during treatment (hazard ratio (HR) 1.81 and 95% confidence interval (CI) 1.15-2.85) and presence of folic acid in plasma at diagnosis (HR 2.09, 95% CI: 1.24, 3.52) and during treatment (HR 2.31, 95% CI: 1.29, 4.13) were associated with an increased risk of toxicities.

CONCLUSIONS

This study suggests a potential association between folic acid and capecitabine-induced toxicities, providing a rationale to study diet-drug interactions and raise further awareness of the use of dietary supplements during oncological treatment.

CLINICAL TRIAL DETAILS

This trial was registered at clinicaltrials.gov as NCT03191110.

Metabolomic Effects of Folic Acid Supplementation in Adults: Evidence from the FACT Trial

BACKGROUND

Folic acid (FA) is the oxidized form of folate found in supplements and FA-fortified foods. Most FA is reduced by dihydrofolate reductase to 5-methyltetrahydrofolate (5mTHF); the latter is the form of folate naturally found in foods. Ingestion of FA increases the plasma levels of both 5mTHF and unmetabolized FA (UMFA). Limited information is available on the downstream metabolic effects of FA supplementation, including potential effects associated with UMFA.

OBJECTIVE

We aimed to assess the metabolic effects of FA-supplementation, and the associations of plasma 5mTHF and UMFA with the metabolome in FA-naïve Bangladeshi adults.

METHODS

Sixty participants were selected from the Folic Acid and Creatine Trial; half received 800 μg FA/day for 12 weeks and half placebo. Plasma metabolome profiles were measured by high-resolution mass spectrometry, including 170 identified metabolites and 26,541 metabolic features. Penalized regression methods were used to assess the associations of targeted metabolites with FA-supplementation, plasma 5mTHF, and plasma UMFA. Pathway analyses were conducted using Mummichog.

RESULTS

In penalized models of identified metabolites, FA-supplementation was associated with higher choline. Changes in 5mTHF concentrations were positively associated with metabolites involved in amino acid metabolism (5-hydroxyindoleacetic acid, acetylmethionine, creatinine, guanidinoacetate, hydroxyproline/n-acetylalanine) and 2 fatty acids (docosahexaenoic acid and linoleic acid). Changes in 5mTHF concentrations were negatively associated with acetylglutamate, acetyllysine, carnitine, propionyl carnitine, cinnamic acid, homogentisate, arachidonic acid, and nicotine. UMFA concentrations were associated with lower levels of arachidonic acid. Together, metabolites selected across all models were related to lipids, aromatic amino acid metabolism, and the urea cycle. Analyses of nontargeted metabolic features identified additional pathways associated with FA supplementation.

CONCLUSION

In addition to the recapitulation of several expected metabolic changes associated with 5mTHF, we observed additional metabolites/pathways associated with FA-supplementation and UMFA. Further studies are needed to confirm these associations and assess their potential implications for human health.

TRIAL REGISTRATION NUMBER

This trial was registered at https://clinicaltrials.gov as NCT01050556.

Supplementation with (6S)-5-methyltetrahydrofolic acid appears as effective as folic acid in maintaining maternal folate status while reducing unmetabolised folic acid in maternal plasma: a randomised trial of pregnant women in Canada

Folic acid supplementation is recommended during pregnancy to support healthy fetal development; (6S)-5-methyltetrahydrofolic acid ((6S)-5-MTHF) is available in some commercial prenatal vitamins as an alternative to folic acid, but its effect on blood folate status during pregnancy is unknown. To address this, we randomised sixty pregnant individuals at 8-21 weeks' gestation to 0·6 mg/d folic acid or (6S)-5-MTHF × 16 weeks. Fasting blood specimens were collected at baseline and after 16 weeks (endline). Erythrocyte and serum folate were quantified via microbiological assay (as globally recommended) and plasma unmetabolised folic acid (UMFA) via LC-MS/MS. Differences in biochemical folate markers between groups were explored using multivariable linear/quantile regression, adjusting for baseline concentrations, dietary folate intake and gestational weeks. At endline (n 54), the mean values and standard deviations (or median, inter-quartile range) of erythrocyte folate, serum folate and plasma UMFA (nmol/l) in those supplemented with (6S)-5-MTHF v. folic acid, respectively, were 1826 (sd 471) and 1998 (sd 421); 70 (sd 13) and 78 (sd 17); 0·5 (0·4, 0·8) and 1·3 (0·9, 2·1). In regression analyses, erythrocyte and serum folate did not differ by treatment group; however, concentrations of plasma UMFA in pregnancy were 0·6 nmol/l higher (95 % CI 0·2, 1·1) in those supplementing with folic acid as compared with (6S)-5-MTHF. In conclusion, supplementation with (6S)-5-MTHF may reduce plasma UMFA by ∼50 % as compared with supplementation with folic acid, the biological relevance of which is unclear. As folate is currently available for purchase in both forms, the impact of circulating maternal UMFA on perinatal outcomes needs to be determined.

Folate regulation of planar cell polarity pathway and F-actin through folate receptor alpha

Folate deficiency contribute to neural tube defects (NTDs) which could be rescued by folate supplementation. However, the underlying mechanisms are still not fully understood. Besides, there is considerable controversy concerning the forms of folate used for supplementation. To address this controversy, we prepared culture medium with different forms of folate, folic acid (FA), and 5-methyltetrahydrofolate (5mTHF), at concentrations of 5 μM, 500 nM, 50 nM, and folate free, respectively. Mouse embryonic fibroblasts (MEFs) were treated with different folates continuously for three passages, and cell proliferation and F-actin were monitored. We determined that compared to 5mTHF, FA showed stronger effects on promoting cell proliferation and F-actin formation. We also found that FOLR1 protein level was positively regulated by folate concentration and the non-canonical Wnt/planar cell polarity (PCP) pathway signaling was significantly enriched among different folate conditions in RNA-sequencing analyses. We demonstrated for the first time that FOLR1 could promote the transcription of Vangl2, one of PCP core genes. The transcription of Vangl2 was down-regulated under folate-deficient condition, which resulted in a decrease in PCP activity and F-actin formation. In summary, we identified a distinct advantage of FA in cell proliferation and F-actin formation over 5mTHF, as well as demonstrating that FOLR1 could promote transcription of Vangl2 and provide a new mechanism by which folate deficiency can contribute to the etiology of NTDs.

Folate - a scoping review for Nordic Nutrition Recommendations 2023

Folate is an essential micronutrient for normal development and metabolic function, and folate deficiency is associated with an increased risk of cancer, cardiovascular disease, mental dysfuntion and negative pregnancy outcomes. When estimating folate requirements, one must consider different bioavailability and functionality between synthetic folic acid and dietary folate, together with increased needs of folate in women of fertile age, pregnant and lactating women, preterm and small for gestational age weight infants and individuals who are homozygote for the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism. In order to achieve an adequate metabolic status based on the metabolic marker total homocysteine, and not merely the absence of clinical signs of folate deficiency, the recommended intake of folate differs according to age, pregnancy and lactation. According to the World Health Organization, a decision limit for folate deficiency in adults is serum folate level below 10 nmol/L, and in women of fertile age a red blood cell folate level below 906 nmol/L in order to prevent neural tube defects. Qualified systematic reviews along with identified relevant literature have been used for this scoping review prepared for the Nordic Nutrition Recommendations 2023.

B Vitamins, Glucoronolactone and the Immune System: Bioavailability, Doses and Efficiency

The present review deals with two main ingredients of energy/power drinks: B vitamins and glucuronolactone and their possible effect on the immune system. There is a strong relationship between the recommended daily dose of selected B vitamins and a functional immune system. Regarding specific B vitamins: (1) Riboflavin is necessary for the optimization of reactive oxygen species (ROS) in the fight against bacterial infections caused by Staphylococcus aureus and Listeria monocytogenes. (2) Niacin administered within normal doses to obese rats can change the phenotype of skeletal fibers, and thereby affect muscle metabolism. This metabolic phenotype induced by niacin treatment is also confirmed by stimulation of the expression of genes involved in the metabolism of free fatty acids (FFAs) and oxidative phosphorylation at this level. (3) Vitamin B5 effects depend primarily on the dose, thus large doses can cause diarrhea or functional disorders of the digestive tract whereas normal levels are effective in wound healing, liver detoxification, and joint health support. (4) High vitamin B6 concentrations (>2000 mg per day) have been shown to exert a significant negative impact on the dorsal root ganglia. Whereas, at doses of approximately 70 ng/mL, sensory symptoms were reported in 80% of cases. (5) Chronic increases in vitamin B12 have been associated with the increased incidence of solid cancers. Additionally, glucuronolactone, whose effects are not well known, represents a controversial compound. (6) Supplementing with D-glucarates, such as glucuronolactone, may help the body's natural defense system function better to inhibit different tumor promoters and carcinogens and their consequences. Cumulatively, the present review aims to evaluate the relationship between the selected B vitamins group, glucuronolactone, and the immune system and their associations to bioavailability, doses, and efficiency.

Analysis of the mediating role of BMI in associations of different folate forms with hepatic steatosis and liver fibrosis in adolescents in the USA: results from the NHANES 2017-2018

Background

Most studies have explored the relationship between serum total folate and nonalcoholic fatty liver disease (NAFLD) in adults, but there has been no study on the relationship between different folate forms and hepatic steatosis or liver stiffness in adolescents.

Objective

To investigate the association of different folate forms with hepatic steatosis or liver stiffness in adolescents, and further explore the intermediary role of BMI in this relationship.

Methods

The cross-sectional study included 549 participants from the 2017-2018 National Health and Nutrition Inspection Survey (NHANES) survey cycle who had complete data. Four folate data (red blood cell folate, serum total folate, 5-methyl-tetrahydrofolate and folic acid) were included in our study. Controlled attenuation parameters (CAP) and liver stiffness came from the results of liver ultrasound transient elastography. We used linear regression to analyze the relationship between different forms of folate and CAP or liver stiffness, and logistic regression to analyze the relationship between different forms of folate and NAFLD or significant fibrosis. We also used restricted cubic splines to analyze the nonlinear relationship between different forms of folate and NAFLD or significant fibrosis. Finally, we used regression-based intermediary analysis to distinguish the direct and BMI-mediated effects of folate on CAP or liver stiffness. All the analyses adjusted the relevant covariates.

Results

The means of CAP and liver hardness in this study were 223.02dB/m and 5.03kPa, respectively. We found that in model 2, there was a negative correlation between serum total folate (β: -18.53; 95%CI: -29.32 to -7.73) or 5-methyltetrahydrofolate (β: -14.13; 95%CI: -28.98 to -7.86) and CAP. However, when the BMI was further adjusted in model 3, this negative correlation no longer existed (serum total folate: β: -8.36; 95%CI: -17.69 to 0.97; 5-methyltetrahydrofolate: β: -8.05; 95%CI: -17.19 to 1.09). Similarly, we found a negative correlation between serum total folate or 5-Methyl-tetrahydrofolate and liver stiffness in model 2. There was no significant correlation between red blood cell folate or folic acid and CAP or liver stiffness in either model 2 or model 3. The nonlinear relationship between different folate forms and NAFLD or significant fibrosis was not significant. It is estimated that 76% of the total association between serum total folate and CAP is mediated by BMI. The mediating proportion of BMI in the total correlation between serum total folate and liver stiffness was 50%. Similarly, we found that BMI significantly mediated the relationship between 5-Methyl-tetrahydrofolate and CAP or liver stiffness, with a mediating ratio of 77% and 49%, respectively.

Conclusion

Our results show that serum total folate or 5-Methyl-tetrahydrofolate are negatively correlated with hepatic steatosis or liver stiffness in adolescents, and BMI plays major mediating role in this relationship. Our findings emphasize the importance of monitoring the concentration of serum folate, not just the serum total folate concentration.

Fructooligosaccharide feeding during gestation to pregnant mice provided excessive folic acid decreases maternal and female fetal oxidative stress by increasing intestinal microbe-derived hydrogen gas

Fructooligosaccharide (FOS) is fermented by intestinal microbes to generate intestinal microbe-derived hydrogen gas (IMDH). Oxidative stress increases during gestation, whereas hydrogen gas has antioxidant effects with therapeutic benefits. We have previously reported that the offspring from a pregnant, excessive folic acid mouse model (PEFAM) had abnormal glucose metabolism after growth. We hypothesized that IMDH by FOS feeding during gestation in PEFAM would suppress maternal and fetal oxidative stress. C57BL/6J mice on day 1 of gestation were divided into 3 groups and dissected at gestational day 18. The control (CONT) diet was AIN-93G containing folic acid 2 mg/kg diet; PEFAM was fed with an excessive folic acid (EFA) diet containing folic acid 40 mg/kg diet, and the EFA-FOS diet was replaced half of the sucrose in the EFA diet. Hydrogen gas concentrations in maternal livers and whole fetuses in EFA-FOS were significantly higher than those in CONT and EFA, respectively (P < .05). Maternal and fetal 8-hydroxy-2'-deoxyguanosine in EFA-FOS were not significantly different from those in the CONT group, whereas those in the EFA group were significantly increased compared with CONT and EFA-FOS (P < .05). In EFA-FOS, expression of protein and mRNA of superoxide dismutase and heme oxygenase 1 in mothers and superoxide dismutase in fetuses were not significantly different from those in CONT, whereas those in EFA were significantly increased (P < .05). The protein expression of Nrf2 in mothers and fetuses were not significantly different between EFA-FOS and CONT. Therefore, FOS feeding to PEFAM during gestation decreases maternal and fetal oxidative stress through IMDH.

Uncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review

This review delves into the intricate relationship between excess folate (vitamin B9) intake, especially its synthetic form, namely, folic acid, and its implications on health and disease. While folate plays a pivotal role in the one-carbon cycle, which is essential for DNA synthesis, repair, and methylation, concerns arise about its excessive intake. The literature underscores potential deleterious effects, such as an increased risk of carcinogenesis; disruption in DNA methylation; and impacts on embryogenesis, pregnancy outcomes, neurodevelopment, and disease risk. Notably, these consequences stretch beyond the immediate effects, potentially influencing future generations through epigenetic reprogramming. The molecular mechanisms underlying these effects were examined, including altered one-carbon metabolism, the accumulation of unmetabolized folic acid, vitamin-B12-dependent mechanisms, altered methylation patterns, and interactions with critical receptors and signaling pathways. Furthermore, differences in the effects and mechanisms mediated by folic acid compared with natural folate are highlighted. Given the widespread folic acid supplementation, it is imperative to further research its optimal intake levels and the molecular pathways impacted by its excessive intake, ensuring the health and well-being of the global population.

Scientific opinion on the tolerable upper intake level for folate

Following a request from the European Commission (EC), the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the revision of the tolerable upper intake level (UL) for folic acid/folate. Systematic reviews of the literature were conducted to assess evidence on priority adverse health effects of excess intake of folate (including folic acid and the other authorised forms, (6S)-5-methyltetrahydrofolic acid glucosamine and l-5-methyltetrahydrofolic acid calcium salts), namely risk of cobalamin-dependent neuropathy, cognitive decline among people with low cobalamin status, and colorectal cancer and prostate cancer. The evidence is insufficient to conclude on a positive and causal relationship between the dietary intake of folate and impaired cognitive function, risk of colorectal and prostate cancer. The risk of progression of neurological symptoms in cobalamin-deficient patients is considered as the critical effect to establish an UL for folic acid. No new evidence has been published that could improve the characterisation of the dose-response between folic acid intake and resolution of megaloblastic anaemia in cobalamin-deficient individuals. The ULs for folic acid previously established by the Scientific Committee on Food are retained for all population groups, i.e. 1000 μg/day for adults, including pregnant and lactating women, 200 μg/day for children aged 1-3 years, 300 μg/day for 4-6 years, 400 μg/day for 7-10 years, 600 μg/day for 11-14 years and 800 μg/day for 15-17 years. A UL of 200 μg/day is established for infants aged 4-11 months. The ULs apply to the combined intake of folic acid, (6S)-5-methyltetrahydrofolic acid glucosamine and l-5-methyltetrahydrofolic acid calcium salts, under their authorised conditions of use. It is unlikely that the ULs for supplemental folate are exceeded in European populations, except for regular users of food supplements containing high doses of folic acid/5-methyl-tetrahydrofolic acid salts.

Precision Nutrition: The Hype Is Exceeding the Science and Evidentiary Standards Needed to Inform Public Health Recommendations for Prevention of Chronic Disease

As dietary guidance for populations shifts from preventing deficiency disorders to chronic disease risk reduction, the biology supporting such guidance becomes more complex due to the multifactorial risk profile of disease and inherent population heterogeneity in the diet-disease relationship. Diet is a primary driver of chronic disease risk, and population-based guidance should account for individual responses. Cascading effects on evidentiary standards for population-based guidance are not straightforward. Precision remains a consideration for dietary guidance to prevent deficiency through the identification of population subgroups with unique nutritional needs. Reducing chronic disease through diet requires greater precision in (a) establishing essential nutrient needs throughout the life cycle in both health and disease; (b) considering effects of nutrients and other food substances on metabolic, immunological, inflammatory, and other physiological responses supporting healthy aging; and (c) considering healthy eating behaviors. Herein we provide a template for guiding population-based eating recommendations for reducing chronic diseases in heterogenous populations.

The Membrane Phospholipidomics Research of Oxidatively Damaged INS-1 Pancreatic Beta Cells Intervened by the Effective Constituents of Anemarrhenae Asphodeloides Rhizoma

The rhizoma of Anemarrhenae asphodeloides has a long history of hypoglycemic use in Chinese traditional medicine. In this article, 400 μmol/L H2 O2 induced normal INS-1 pancreatic beta cells to establish experimental model of oxidative damage. Quercetin was used as a positive drug, and mangiferin and its ethanolic extract were selected as therapeutic agents in an oxidative damage model to evaluate the ameliorative effect of the active ingredients of Anemarrhenae asphodeloides rhizoma on oxidative damage in INS-1 pancreatic β-cells. Building a qualitative analysis method of membrane phospholipids of INS-1 pancreatic beta cells and identified 82 phospholipids based on the UPLC/Q-TOF MS technology, which could provide a database for further statistics analysis. OPLS-DA was used to screen the phospholipid biomarkers from the raw data. Exploring the biological significances of these biomarkers, and discussing the toxic effect of the effective components of Anemarrhena asphodeloides rhizoma, on oxidatively damaged INS-1 pancreatic beta cell.

Human milk unmetabolized folic acid is increased following supplementation with synthetic folic acid as compared to (6S)-5-methyltetrahydrofolic acid

Folic acid supplementation is recommended perinatally, but may increase unmetabolized folic acid (UMFA) in human milk; this is concerning as it is an inactive form which may be less bioavailable for the infant. "Natural" (6S)-5-methyltetrahydrofolic acid [(6S)-5-MTHF] is available as an alternative to folic acid, and may prevent the accumulation of UMFA in human milk. Pregnant women (n = 60) were enrolled at 8-21 weeks of gestation and randomized to 0.6 mg/day folic acid or (6S)-5-MTHF. At ~ 1-week postpartum, participants provided a human milk specimen. Total human milk folate (nmol/L) and concentrations of UMFA (nmol/L) were quantified via LC-MS/MS. Differences between groups were evaluated using multivariable quantile/linear regression, adjusting for dietary folate, weeks supplementing, and milk collection methods. No significant difference in total milk folate was found; however, the median milk UMFA concentration was 11 nmol/L higher in those receiving folic acid versus (6S)-5-MTHF (95% CI = 6.4-17 nmol/L), with UMFA representing 28% and 2% of total milk folate. In conclusion, the form of supplemental folate had markedly differential effects on the human milk folate profile, with folic acid increasing the mean proportion of milk UMFA by ~ 14-fold. Investigation of whether increased UMFA impacts folate-related metabolism and infant health outcomes is required.

High Serum Folate Concentration, Vitamin B12 Deficiency, and Anthropometric Nutritional Status in Brazilian Children Aged 6-59 Months: Data from the Brazilian National Survey of Child Nutrition

BACKGROUND

Vitamin B12 and folate are key nutrients that help children reach their full potential in growth and development; however, little is known about the status of these vitamins in Brazilian children.

OBJECTIVES

To describe the serum concentrations of vitamin B12 and folate, to investigate the association between high folate concentration (HFC) and vitamin B12 deficiency, and to evaluate the association between vitamin B12 and stunting/underweight in Brazilian children aged 6-59 mo.

METHODS

Data from 7417 children aged 6-59 mo collected during the Brazilian National Survey on Child Nutrition were used. Serum concentrations of vitamin B12 of <150 pmol/L and folate of <10 nmol/L were classified as deficient, and folate concentrations of >45.3 nmol/L were classified as HFC. Children with length/height-for-age z-score of less than -2 were considered stunted, and those with weight-for-age z-score of less than -2 were underweight. Logistic regression models were performed.

RESULTS

In Brazil, 14.2% (95% CI: 12.2, 16.1) of children aged 6-59 mo had vitamin B12 deficiency, 1.1% (95% CI: 0.5, 1.6) had folate deficiency, and 36.9% (95% CI: 33.4, 40.3) had HFC. Vitamin B12 deficiency was higher in children from the northern region of Brazil (28.5%), between 6 and 24 mo (25.3%), whose mothers had lower formal education (0-7 y; 18.7%). Children with HFC had 62% lower odds (OR: 0.38; 95% CI: 0.27, 0.54) of vitamin B12 deficiency than those with normal/deficient folate. Children with vitamin B12 deficiency and normal/deficient folate had higher odds of stunting (OR: 1.58; 95% CI: 1.02, 2.43) than children without vitamin B12 deficiency and normal/deficient folate.

CONCLUSIONS

Vitamin B12 deficiency is a public health problem among Brazilian children aged <2 y with vulnerable socioeconomic status. HFC was inversely associated with vitamin B12 deficiency, and lower odds of stunting were observed in children with HFC and vitamin B12 deficiency than in those with vitamin B12 deficiency and normal/deficient folate.

Folate, folic acid, and chemotherapy-induced toxicities: a systematic literature review

Folate metabolism is a target for various chemotherapeutic drugs. Folate and its synthetic variant folic acid are B-vitamins. To what extent these vitamins impact treatment tolerance in patients with cancer remains unclear. A systematic literature review was conducted on intake and status of folate and folic acid in relation to chemotherapy-induced toxicities in children and adults with cancer. A total of 6,231 publications were identified, of which 40 publications met the inclusion criteria. In 12 out of 22 studies focusing on antifolates, a deficient folate status and lower folate and folic acid intake were associated with a higher risk of toxicities. In 8 out of 14 studies focusing on fluoropyrimidine treatments, a higher folate status and intake were associated with a higher risk of toxicities. These findings might explain interindividual differences in treatment tolerance and highlight the importance of evaluating nutritional status in oncology care.

Homocysteine-a retrospective and prospective appraisal

The biologically important amino acid homocysteine links sulfur, methionine, and one-carbon metabolism. This review describes its initial discovery, the identification of the clinical condition of "homocystinuria" and the recognition of its close relationship to folate and vitamin B12 metabolism. It discusses the history behind its current association with diverse diseases including neural tube defects, cardio- and cerebrovascular disease and, more recently, dementia and Alzheimer's Disease. It also explores current controversies and considers potential future research directions. It is intended to give a general overview of homocysteine in relation to health and disease.

Variations in folate prescriptions for patients with the MTHFR genetic polymorphisms: A case series study

Background

Over 48.5 million couples are reported with infertility worldwide. Health policy recommends folic acid in women of childbearing age, particularly in preconception and pregnancy which results in women purchasing over-the-counter prenatal multivitamins containing folic acid through pharmacies and other retail outlets. Emerging studies are investigating whether other forms of supplemental folate are more suitable, particularly for those with methylenetetrahydrofolate reductase (MTHFR) polymorphisms. This case series aimed to document variations in forms and dosage of folate prescribed by Australian practitioners to patients with diagnosed infertility and MTHFR polymorphisms.

Methods

Australian practitioners were invited to complete a retrospective case report form for patients that presented with unexplained infertility. This case report form documented the form and dose of folate that practitioners were prescribing to their infertility patient with MTHFR polymorphisms, together with their fertility history.

Results

Six practitioners submitted case information for 12 patients with diagnosed infertility and MTHFR polymorphisms. All patients had been advised by their practitioner to remove folic acid in supplemental form and were prescribed 5-methyltetrahydrofolate (5-MTHF) or a combination of 5-MTHF and folinic acid, at higher doses than the Australian recommended dose (mean daily maximum prescribed dose: 2325μg). Eleven patients conceived within the treatment period (average treatment of one year) and ten were reported as having a live birth.

Conclusion

This case series has highlighted clinical practices that vary from the recommendations by Australian policy. Further research is required to verify the clinical importance of variations in folate prescriptions for women with MTHFR polymorphisms and how folate recommendations may need to change depending on these polymorphisms. This has direct relevance to those prescribing at the pharmacy and retail level, specifically pharmacists and pharmacy assistants.

Does maternal genetic liability to folate deficiency influence the risk of antiseizure medication-associated language impairment and autistic traits in children of women with epilepsy?

BACKGROUND

Prenatal exposure to antiseizure medication (ASM) may lead to low plasma folate concentrations and is associated with impaired neurodevelopment.

OBJECTIVE

To examine whether maternal genetic liability to folate deficiency interacts with ASM-associated risk of language impairment and autistic traits in children of women with epilepsy.

METHODS

We included children of women with and without epilepsy and with available genetic data enrolled in the Norwegian Mother, Father, and Child Cohort Study (MoBa). Information on ASM use, folic acid supplement use and dose, dietary folate intake, child autistic traits, and child language impairment was obtained from parent-reported questionnaires. Using logistic regression, we examined the interaction between prenatal ASM exposure and maternal genetic liability to folate deficiency expressed as polygenic risk score (PRS) of low folate concentrations or maternal rs1801133 genotype (CC or CT/TT) on risk of language impairment or autistic traits.

RESULTS

We included 96 children of women with ASM-treated epilepsy, 131 children of women with ASM-untreated epilepsy, and 37,249 children of women without epilepsy. The PRS of low folate concentrations or the maternal rs1801133 genotype did not interact with the ASM-associated risk of language impairment or autistic traits in ASM-exposed children of women with epilepsy compared to ASM-unexposed children aged 1.5-8 years. ASM-exposed children had increased risk of adverse neurodevelopment regardless of maternal rs1801133 genotype (adjusted odds ratio (aOR) for language impairment age 8 years was 2.88 (95% confidence interval (CI) 1.00-8.26) if CC and aOR 2.88 (CI 1.10-7.53) if CT/TT genotypes). In children of women without epilepsy aged 3 years, those with maternal rs1801133 CT/TT compared to CC genotype had increased risk of language impairment (aOR 1.18, CI 1.05-1.34).

CONCLUSIONS

In this cohort of pregnant women reporting widespread use of folic acid supplements, maternal genetic liability to folate deficiency did not significantly influence the ASM-associated risk of impaired neurodevelopment.

Effects of folic acid supplementation in pregnant mice on glucose metabolism disorders in male offspring induced by lipopolysaccharide exposure during pregnancy

The DOHaD theory suggests that adverse environmental factors in early life may lead to the development of metabolic diseases including diabetes and hypertension in adult offspring through epigenetic mechanisms such as DNA methylation. Folic acid (FA) is an important methyl donor in vivo and participates in DNA replication and methylation. The preliminary experimental results of our group demonstrated that lipopolysaccharide (LPS, 50 µg/kg/d) exposure during pregnancy could lead to glucose metabolism disorders in male offspring, but not female offspring; however, the effect of folic acid supplementation on glucose metabolism disorders in male offspring induced by LPS exposure remains unclear. Therefore, in this study, pregnant mice were exposed to LPS on gestational day (GD) 15-17 and were given three doses of FA supplementation (2 mg/kg, 5 mg/kg, or 40 mg/kg) from mating to lactation to explore its effect on glucose metabolism in male offspring and the potential mechanism. This study confirmed that FA supplementation of 5 mg/kg in pregnant mice improved glucose metabolism in LPS-exposed offspring during pregnancy by regulating gene expression.