Homocysteine homeostasis in the rat is maintained by compensatory changes in cystathionine β-synthase, betaine-homocysteine methyltransferase, and phosphatidylethanolamine N-methyltransferase gene transcription occurring in response to maternal protein and folic acid intake during pregnancy and fat intake after weaning

Caloric restriction can affect one-carbon metabolism during pregnancy in the rat: A transgenerational model

One-carbon metabolism is critical to pregnancy outcomes, because it determines the availability of nutrients involved in cell divisions and DNA methylation. The aim of this study was to analyze how 50% prenatal calorie restriction affected one-carbon metabolism in pregnant Wistar rats of the F0 to F2 generations. Mean choline (p < 0.001), betaine (p < 0.001), and S-adenosylmethionine (SAM) (p < 0.05) concentrations were respectively about 40%, 45%, and 20% lower in the F0_R (R - restricted diet) than in the F0_C (C - control diet). Homocysteine, S-adenosylhomocysteine (SAH), and trimethylamine oxide concentrations were unaffected. In the F1_R, the SAM-to-SAH ratio was 25% higher (p < 0.05) than in the F1_C. No differences between the C and R groups were observed in the F2 generation. The SAM concentrations in the F1_R were higher than in the F0_R and the F2_R (p < 0.01). The relative transcript levels of Mat1a, Bhmt, Cbs, Pemt, and Mthfr were only slightly affected by the diet, with changes of less than a factor of 2.0. Cbs activity in the F2_R was significantly higher than in the F2_C (p < 0.001). Food deprivation may affect one-carbon metabolism in pregnant rats, but it does not stimulate persistent metabolic changes that can be observed during the pregnancy of their progeny of the F1 or F2 generations.

The impact of folic acid supplementation on gestational and long term health: Critical temporal windows, benefits and risks

Highlights

Associations between FA supplementation in pregnancy and effects on offspring's NTDs, allergy/respiratory problems, cancer and behaviour problems as been studied.There is growing concern about the effects of excessive FA supplementation, whether in terms of doses or times of exposure.FA supplementation in the periconceptional period is protective against NTDs while in later periods it could be deleterious.A daily dose of 0.4 mg FA in the periconceptional period seems to be effective and safe.

Abstract

Maternal folic acid (FA) supplementation is one of the most popular nutritional interventions during pregnancy for its protective effect against neural tube defects (NTDs).The purposes of this review are: (a) to gather the current evidence regarding supplementation of maternal diet with FA and (b) to problematize the available literature in terms of dosages, critical temporal windows, and its potential benefits and risks.The expression (pregnancy OR fetus OR offspring OR mother) AND ("folic acid" AND supplementation) was searched on PubMed database, filtering for articles published from 2005 to 2014. Publications referring to FA supplementation during the periconceptional period or pregnancy in which there was a conclusion about the effects of isolated FA supplementation on pregnant woman, pregnancy or offspring were included. Of the initial 1182 papers, 109 fulfilled the inclusion criteria.The majority of the publications reported FA supplementation outcomes on offspring's health, with emphasis in NTDs, allergy/respiratory problems, cancer and behaviour problems. Some inconsistency is observed on the impact of FA supplementation on different outcomes, except for NTDs. It is also visible an increased concern about the impact of excessive supplementation, either in terms of doses or exposure's duration.In conclusion, there is a growing interest in FA supplementation issues. The protective effect of FA supplementation over NTDs has been confirmed, being the periconceptional period a critical window, and it is frequently suggested that allergy/respiratory outcomes arise from (excessive) FA supplementation particularly later in pregnancy. Further research on critical doses and time of exposure should be conducted.

Maternal Folate Status and the BHMT c.716G>A Polymorphism Affect the Betaine Dimethylglycine Pathway during Pregnancy

The effect of the betaine: homocysteine methyltransferase BHMT c.716G>A (G: guanosine; A: adenosine) single nucleotide polymorphism (SNP) on the BHMT pathway is unknown during pregnancy. We hypothesised that it impairs betaine to dimethylglycine conversion and that folate status modifies its effect. We studied 612 women from the Reus Tarragona Birth Cohort from ≤12 gestational weeks (GW) throughout pregnancy. The frequency of the variant BHMT c.716A allele was 30.8% (95% confidence interval (CI): 28.3, 33.5). In participants with normal-high plasma folate status (>13.4 nmol/L), least square geometric mean [95% CI] plasma dimethylglycine (pDMG, µmol/L) was lower in the GA (2.35 [2.23, 2.47]) versus GG (2.58 [2.46, 2.70]) genotype at ≤12 GW (p < 0.05) and in the GA (2.08 [1.97, 2.19]) and AA (1.94 [1.75, 2.16]) versus GG (2.29 [2.18, 2.40]) genotypes at 15 GW (p < 0.05). No differences in pDMG between genotypes were observed in participants with possible folate deficiency (≤13.4 nmol/L) (p for interactions at ≤12 GW: 0.023 and 15 GW: 0.038). PDMG was lower in participants with the AA versus GG genotype at 34 GW (2.01 [1.79, 2.25] versus 2.44 [2.16, 2.76] and at labour, 2.51 [2.39, 2.64] versus 3.00 [2.84, 3.18], (p < 0.01)). Possible deficiency compared to normal-high folate status was associated with higher pDMG in multiple linear regression analysis (β coefficients [SEM] ranging from 0.07 [0.04], p < 0.05 to 0.20 [0.04], p < 0.001 in models from early and mid-late pregnancy) and the AA compared to GG genotype was associated with lower pDMG (β coefficients [SEM] ranging from −0.11 [0.06], p = 0.055 to −0.23 [0.06], p < 0.001). Conclusion: During pregnancy, the BHMT pathway is affected by folate status and by the variant BHMT c.716A allele.

Folic acid supplementation in pregnancy: are there devils in the detail?

Maternal folic acid (FA) supplementation is well recognised to protect against neural tube defects. Folate is a critical cofactor in one-carbon metabolism involved in the epigenetic regulation of transcription that underpins development. Thus, it is possible that maternal FA supplementation may have additional, unforeseen persistent effects in the offspring. This is supported by the modification by maternal supplementation with one-carbon donors and FA of the epigenetic regulation of offspring phenotype in mutant mice. The present article reviews studies in human subjects and experimental animals of the effect of maternal FA intake and phenotypic outcomes in the offspring. Maternal FA intake was associated with a short-term increased incidence of allergy-related respiratory impairment in children and multigenerational respiratory impairment in rats. Higher maternal folate status during pregnancy was associated positively with insulin resistance in 6-year-olds. In rats, maternal FA supplementation modified hepatic metabolism and vascular function through altered transcription, in some cases underpinned by epigenetic changes. FA supplementation in pregnant rats increased mammary tumorigenesis, but decreased colorectal cancer in the offspring. Maternal FA supplementation decreased a range of congenital cardiac defects in children. These findings support the view that maternal FA supplementation induces persistent changes in a number of phenotypic outcomes in the offspring. However, the number of studies is limited and insufficient to indicate a need to change current recommendations for FA intake in pregnancy. Nevertheless, such effects should be investigated thoroughly in order to support firm conclusions about the risk of unanticipated long-term negative effects of maternal FA supplementation in humans.