High concentrations of folate and unmetabolized folic acid in a cohort of pregnant Canadian women and umbilical cord blood

Mandatory fortification, prevalent supplement use, and public health guidelines recommending periconceptional supplementation have increased folic acid intakes in North American pregnant women. However, the effects of increased folic acid intakes during pregnancy on maternal and cord blood folate co...

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Bibliographic Details
Published in:The American journal of clinical nutrition 2015-10, Vol.102 (4), p.848-857
Main Authors: Plumptre, Lesley, Masih, Shannon P, Ly, Anna, Aufreiter, Susanne, Sohn, Kyoung-Jin, Croxford, Ruth, Lausman, Andrea Y, Berger, Howard, O'Connor, Deborah L, Kim, Young-In
Format: Article
Language:English
Subjects:
Adult
Blood
Canada
Dietary Supplements
Energy Intake
Female
Fetal Blood - chemistry
Folic Acid - administration & dosage
Folic Acid - adverse effects
Folic Acid - blood
Gene Frequency
Genetic Variation
Genotype
Genotype & phenotype
Homocysteine - blood
Humans
Logistic Models
Maternal Nutritional Physiological Phenomena
Methylenetetrahydrofolate Reductase (NADPH2) - genetics
Methylenetetrahydrofolate Reductase (NADPH2) - metabolism
Middle Aged
Nutrition Assessment
Polymorphism, Single Nucleotide
Pregnancy
Prospective Studies
Surveys and Questionnaires
Tetrahydrofolate Dehydrogenase - genetics
Tetrahydrofolate Dehydrogenase - metabolism
Vitamin B
Young Adult
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Summary:Mandatory fortification, prevalent supplement use, and public health guidelines recommending periconceptional supplementation have increased folic acid intakes in North American pregnant women. However, the effects of increased folic acid intakes during pregnancy on maternal and cord blood folate concentrations have not been well established. In this prospective study, we determined maternal and cord blood concentrations of folate and unmetabolized folic acid (UMFA) in a cohort of pregnant Canadian women and their newborns and examined the effect of maternal intakes of folate and folic acid and fetal genetic variants in folate metabolism on folate status. Folate and folic acid intakes of 368 Canadian pregnant women were assessed in early (0-16 wk) and late (23-37 wk) pregnancy. Blood concentrations of folate and UMFA were measured with the use of immunoassays and liquid chromatography-mass spectrometry, respectively, in maternal samples in early pregnancy (12-16 wk), at delivery (28-42 wk), and in cord blood. Four fetal genetic variants of the 5,10-methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) genes were assessed for their association with cord blood concentrations of folate and UMFA. Geometric mean (95% CI) maternal red blood cell (RBC) folate concentrations were 2417 nmol/L (2362, 2472 nmol/L ) and 2793 nmol/L (2721, 2867 nmol/L ) in early pregnancy and at delivery, respectively. The mean (95% CI) cord RBC folate concentration was 2689 nmol/L (2614, 2765 nmol/L). UMFA was detectable in >90% of maternal and cord plasma samples. Although 3 fetal MTHFR and DHFR genetic variants had no effect, the fetal MTHFR 677TT genotype was associated with significantly lower cord serum (P = 0.03) and higher cord RBC (P = 0.02) folate concentrations than those of the wild type. Notwithstanding differences in assays, maternal and cord RBC folate and plasma UMFA concentrations were higher than previously reported values. Functional ramifications of high folate and UMFA concentrations in maternal and fetal circulation warrant additional investigation because an excess folate status may affect long-term health outcomes of the offspring. This study was registered at www.clinicaltrials.gov as NCT02244684.
ISSN:0002-9165
1938-3207
DOI:10.3945/ajcn.115.110783