The effects of folic acid supplements on coagulation status in pregnancy

Evaluation of the effect of high-dose folic acid on endothelial dysfunction in pre-eclamptic patients: A randomized clinical trial

Background:

Pre-eclampsia as a hypertensive disorder of pregnancy complicates up to 5–10% of pregnancies worldwide. Endothelial dysfunction plays an important role in the pathogenesis of pre-eclampsia. In this study, we aim to evaluate the effect of high-dose folic acid on endothelial dysfunction in pre-eclamptic patients.

Materials and Methods:

In this triple-blinded randomized clinical trial, the enrolled patients were divided randomly into two groups. Folic acid 5.0 mg or placebo was taken daily by oral administration from the initiation of diagnosis until 2 months after delivery by the participants. Every patient's flow-mediated dilation (FMD) was evaluated at the beginning of the study and 2 months after delivery with the same experienced operator at the same period of time (3–5 p.m.) by high-resolution B-mode ultrasonography. Potential confounding variables were included in the independent samples t-test. t-test or Mann–Whitney U-test was used in the comparison of means between the intervention and placebo groups. To compare FMD in each group, before and after the intervention, paired t-test was used.

Results:

Mean value of FMD in intervention (9.64 ± 5.57) and control group (9.30 ± 4.25) has no significant difference before the consumption of drugs (P > 0.05). FMD in intervention group (13.72 ± 7.89) significantly increases after daily consumption of 5 mg folic acid in comparison with control group (10.02 ± 4.81) after daily consumption of placebo (P = 0.002).

Conclusion:

Increased mean of FMD in intervention group shows that this supplement can improve endothelial function and can be significantly affected by maternal blood pressure during pregnancy and some endothelium-dependent disease such as pre-eclampsia and its associated adverse outcomes.

Genetic variant in folate homeostasis is associated with lower warfarin dose in African Americans

The anticoagulant warfarin has >30 million prescriptions per year in the United States. Doses can vary 20-fold between patients, and incorrect dosing can result in serious adverse events. Variation in warfarin pharmacokinetic and pharmacodynamic genes, such as CYP2C9 and VKORC1, do not fully explain the dose variability in African Americans. To identify additional genetic contributors to warfarin dose, we exome sequenced 103 African Americans on stable doses of warfarin at extremes (≤ 35 and ≥ 49 mg/week). We found an association between lower warfarin dose and a population-specific regulatory variant, rs7856096 (P = 1.82 × 10(-8), minor allele frequency = 20.4%), in the folate homeostasis gene folylpolyglutamate synthase (FPGS). We replicated this association in an independent cohort of 372 African American subjects whose stable warfarin doses represented the full dosing spectrum (P = .046). In a combined cohort, adding rs7856096 to the International Warfarin Pharmacogenetic Consortium pharmacogenetic dosing algorithm resulted in a 5.8 mg/week (P = 3.93 × 10(-5)) decrease in warfarin dose for each allele carried. The variant overlaps functional elements and was associated (P = .01) with FPGS gene expression in lymphoblastoid cell lines derived from combined HapMap African populations (N = 326). Our results provide the first evidence linking genetic variation in folate homeostasis to warfarin response.

Association between B-group vitamins and venous thrombosis: systematic review and meta-analysis of epidemiological studies

A homocysteine-independent role for B-group vitamins on venous thrombosis (VT) development has been reported. However, related research findings remain inconsistent. PUBMED, EMBASE, and COCHRANE databases were searched to collect information on all eligible studies to make a meta-analysis about the relationship between B-group vitamins and VT. Literature search results did not suggest a correlation between thiamin, pantothenic acid, niacin, or riboflavin with VT. Based on their correlations in the literature, folic acid, vitamin B12, B6 were considered in the meta-analysis and systematic review. Significant standardized mean differences were obtained for plasma folic acid (-0.55; 95% CI, -0.75 to -0.36) and vitamin B12 (-0.34; 95% CI, -0.55 to -0.13). Reduced levels of folic acid and vitamin B12 may be independent risk factors of VT. Moreover, a qualitative systematic review indicated that low level of vitamin B6 was an independent risk factor of VT. Randomized clinical studies of B-group vitamins supplementation showed varying results on VT prevention. Multivitamin supplementation for VT prevention, regardless of homocysteine level, would be of interest. Further prospective clinical studies are needed to provide additional evidence on the clinical benefits of B-group vitamin supplementation for VT.

Genomic DNA methylation changes in response to folic acid supplementation in a population-based intervention study among women of reproductive age

Folate is a source of one-carbons necessary for DNA methylation, a critical epigenetic modification necessary for genomic structure and function. The use of supplemental folic acid is widespread however; the potential influence on DNA methylation is unclear. We measured global DNA methylation using DNA extracted from samples from a population-based, double-blind randomized trial of folic acid supplementation (100, 400, 4000 µg per day) taken for 6 months; including a 3 month post-supplementation sample. We observed no changes in global DNA methylation in response to up to 4,000 µg/day for 6 months supplementation in DNA extracted from uncoagulated blood (approximates circulating blood). However, when DNA methylation was determined in coagulated samples from the same individuals at the same time, significant time, dose, and MTHFR genotype-dependent changes were observed. The baseline level of DNA methylation was the same for uncoagulated and coagulated samples; marked differences between sample types were observed only after intervention. In DNA from coagulated blood, DNA methylation decreased (−14%; P<0.001) after 1 month of supplementation and 3 months after supplement withdrawal, methylation decreased an additional 23% (P<0.001) with significant variation among individuals (max+17%; min-94%). Decreases in methylation of ≥25% (vs. <25%) after discontinuation of supplementation were strongly associated with genotype: MTHFR CC vs. TT (adjusted odds ratio [aOR] 12.9, 95%CI 6.4, 26.0). The unexpected difference in DNA methylation between DNA extracted from coagulated and uncoagulated samples in response to folic acid supplementation is an important finding for evaluating use of folic acid and investigating the potential effects of folic acid supplementation on coagulation.

Folic acid supplementation improves vascular function in professional dancers with endothelial dysfunction

OBJECTIVE

To determine if folic acid supplementation improves vascular function (brachial artery flow-mediated dilation [FMD]) in professional dancers with known endothelial dysfunction.

DESIGN

Prospective cross-sectional study.

SETTING

Academic institution in the Midwestern United States.

SUBJECTS

Twenty-two professional ballet dancers volunteered for this study.

MAIN OUTCOME MEASURES

Subjects completed a 3-day food record to determine caloric and micronutrient intake. Menstrual status was determined by interview and questionnaire. Endothelial function was determined as flow-induced vasodilation measured by high-frequency ultrasound of the brachial artery. A change in brachial diameter of <5% to hyperemic flow stimulus was defined a priori as endothelial dysfunction. Subjects with abnormal FMD took 10 mg of folic acid daily for 4 weeks, and FMD testing was then repeated. Serum whole blood was measured for folic acid levels before and after supplementation.

RESULTS

Sixty-four percent of dancers (n = 14) had abnormal brachial artery FMD (<5%) (mean ± standard deviation, 2.9% ± 1.5%). After 4 weeks of folic acid supplementation (10 mg/day), FMD improved in all the subjects (7.1% ± 2.3%; P < .0001).

CONCLUSIONS

This study reveals that vascular endothelial function improves in dancers after supplementation with folic acid (10 mg/day) for at least 4 weeks. This finding may have clinically important implications for future cardiovascular disease risk prevention.

Folic acid supplementation improves vascular function in amenorrheic runners

OBJECTIVE

The purpose of this study was to determine if folic acid supplementation improves endothelial vascular function (brachial artery flow-mediated dilation; FMD) in amenorrheic runners.

DESIGN

Prospective cross-sectional study.

SETTING

Academic medical center in the Midwest.

PARTICIPANTS

Ten amenorrheic and 10 eumenorrheic women runners from the community volunteered for this study.

INTERVENTIONS

Each participant was treated with folic acid (10 mg/d) for 4 weeks.

MAIN OUTCOME MEASURES

Brachial artery FMD was measured before and after folic acid supplementation with standard techniques.

RESULTS

The brachial artery FMD response to reactive hyperemia improved after folic acid supplementation in amenorrheic women (3.0% +/- 2.3% vs. 7.7% +/- 4.5%; P = 0.02). In the eumenorrheic control group, there was no change in brachial artery FMD (6.7% +/- 2.0% vs. 5.9% +/- 2.6%; P = 0.52).

CONCLUSIONS

This study demonstrates that brachial artery FMD, an indicator of vascular endothelial function, improves in amenorrheic female runners after short-term supplementation with folic acid.

Folic acid, inflammation, and atherosclerosis: False hopes or the need for better trials?

An increasing body of evidence supports the existence of a strong link between inflammation, endothelial dysfunction, and the onset and progression of atherosclerosis. However, a cause-effect relationship between these phenomena has not been demonstrated yet. Although some inflammatory markers, such as C-reactive protein, have been recently shown to improve risk stratification and to strongly predict cardiovascular outcome, it is largely unknown whether modifications of these markers might provide salutary effects and reduce cardiovascular morbidity and mortality. The B-vitamin folic acid has recently gained attention because of its potential to provide beneficial effects on surrogate end-points, such as endothelial function, in patients at high cardiovascular risk. However, the role of folic acid in mitigating the pro-inflammatory state associated with atherosclerosis is controversial. Despite the theoretical arguments supporting the potential anti-atherosclerotic and anti-inflammatory effects of folic acid, the current evidence is limited, deriving from small trials on different study populations, using folic acid often in combination with other vitamins and for different treatment periods. This review will consider the current evidence supporting the role of some well-established inflammatory markers in predicting cardiovascular outcomes, the mechanisms by which folic acid might exert anti-inflammatory effects, the epidemiological data relating folic acid concentrations with inflammatory markers, the published interventional studies on the effects of folic acid supplementation on these markers, and the factors that need to be considered in designing future trials.