Concentration of folic acid (FA) in serum of Japanese pregnant women

Objectives: Exposure to inorganic arsenic (iAs) is a worldwide health concern. We reported that Japanese children and pregnant women are exposed to moderate levels of iAs through food. Reducing iAs contamination from foods of high iAs is an important issue unique in Japan. Integrated iAs is methylated to less toxic organic forms, and S-adenosyl-L-methyonine (SAM), a common methyl-donor of DNA and histones, is utilized in this process. Chronic consumption of SAM by iAs metabolism due to exposure to iAs might alter the epigenetic modification of genome. The SAM biosynthesis pathway is dependent on folate cycle, and it is possible that ingestion of sufficient folic acid (FA) is protective to iAs induced toxicity. Methods: In the course of our cross-sectional body burden analyses of Pb and iAs in Japanese children and pregnant women, termed "PbAs study", FA concentration in serum of 104 pregnant women was measured. Results: Mean (+/- SEM) of serum FA concentration was 15.8 +/- 1.3 (ng/mL). There are significant number of people showing very high FA (>30 ng/mL), and large fraction of them were taking supplements daily. Conclusions: These results suggested that level of FA ingestion of Japanese pregnant women is high for supporting normal fetal development.