Impact of folic acid and vitamin B12 supplementation on arsenic methylation

A recent study demonstrated that folic acid (FA) and vitamin B12 (B12) supplementation improved arsenic methylation in children, leading to a decrease in monomethyl- (MMAs) and an increase in dimethyl- (DMAs) in both blood and urine. Implementing nutritional interventions could enhance arsenic methylation and elimination in children, thereby reducing arsenic toxicity and improving their nutritional status. This study’s results were published in the Environment International journal.

This double-blind, placebo-controlled trial involved 240 participants aged 8-11 years, who were consuming water from wells with arsenic levels exceeding 50 μg/L. They were advised to switch to wells with lower arsenic levels and were randomly assigned to receive either 400 μg FA + 5 μg B12 or a placebo daily for a period of 12 weeks. Samples of urine and blood were taken at the baseline, week 1 (urine only), and week 12. Generalized estimated equation (GEE) models were utilized to evaluate the impact of the treatment on arsenic levels in both blood and urine.

At the baseline, the mean ± SD total urinary and blood arsenic levels were measured as 91.2 ± 89.5 μg/L and 5.3 ± 2.9 μg/L, respectively. After the follow-up period, there was an overall decrease of 11.7% in total blood arsenic and 17.6% in urinary arsenic. In comparison to the placebo group, the supplementation group showed a notable increase in blood DMAs concentration by of 14.0% and blood secondary methylation index (DMAs/MMAs) by 0.19 at 12 weeks. Additionally, the supplementation group had a significantly higher urinary %DMAs (1.62%) and a significantly lower urinary %MMAs (-1.10%) compared to the placebo group after 1 week. The effects of the treatment were stronger in individuals with higher baseline blood arsenic levels. These results remained consistent across both males and females, as well as participants with varying folate and B12 status at baseline.

Thus, it can be concluded that FA and B12 supplementation resulted in improved arsenic methylation in children, resulting in a reduction in MMAs and an elevation in DMAs in both blood and urine.