Nutritional status has marginal influence on the metabolism of inorganic arsenic in pregnant Bangladeshi women.
BACKGROUND
The interindividual variation in metabolism of inorganic arsenic (iAs), involving methylation via one-carbon metabolism, has been well documented, but the reasons remain unclear.


OBJECTIVE
In this population-based study we aimed to elucidate the effect of nutrition on As methylation among women in Matlab, Bangladesh, where people are chronically exposed to iAs via drinking water.


METHODS
We studied effects of macronutrient status using body mass index (BMI) among 442 women in early pregnancy (gestational week 8), and effects of micronutrient status (plasma folate, vitamin B12, zinc, ferritin, and selenium) among 753 women at gestational week 14. Arsenic metabolites in urine were measured by HPLC combined with hydride generation inductively coupled plasma mass spectrometry.


RESULTS
The median concentration of As in urine was 97 microg/L (range, 5-1,216 microg/L, adjusted by specific gravity). The average proportions of iAs, monomethylarsonic acid, and dimethylarsinic acid in urine in gestational week 8 were 15%, 11%, and 74%, respectively. Thus, the women had efficient As methylation in spite of being poorly nourished (one-third had BMIs < 18.5 kg/m2) and having elevated As exposure, both of which are known to decrease As methylation. The metabolism of iAs was only marginally influenced by micronutrient status, probably because women, especially in pregnancy and with low folate intake, have an efficient betaine-mediated remethylation of homocysteine, which is essential for an efficient As methylation.


CONCLUSIONS
In spite of the high As exposure and prevalent malnutrition, overall As methylation in women in early pregnancy was remarkably efficient. The As exposure level had the greatest impact on As methylation among the studied factors.
Li
Li
L
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Ekström
Eva-Charlotte
EC
Goessler
Walter
W
Lönnerdal
Bo
B
Nermell
Barbro
B
Yunus
Mohammad
M
Rahman
Anisur
A
El Arifeen
Shams
S
Persson
Lars Ake
LA
Vahter
Marie
M
D000328:Adult; D001151:Arsenic / Q000493:pharmacokinetics* / Q000633:toxicity / Q000652:urine; D020261:Arsenic Poisoning / Q000150:complications / Q000378:metabolism; D001459:Bangladesh / Q000453:epidemiology; D015992:Body Mass Index; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006306:Health Surveys; D006801:Humans; D044342:Malnutrition / Q000150:complications; D013058:Mass Spectrometry; D018811:Maternal Exposure / Q000009:adverse effects*; D008745:Methylation; D009752:Nutritional Status; D011247:Pregnancy; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics* / Q000633:toxicity / Q000652:urine
D014874:Water Pollutants, Chemical; D001151:Arsenic