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B vitamins may counter adverse reproductive effects from DDT exposure
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An adequate amount of vitamin B12 and folate could help protect women against the adverse reproductive effects from exposure to DDT, a pesticide and a known endocrine disruptor, according to research published in The American Journal of Clinical Nutrition.
The findings from an investigation of preconception concentrations of plasma B vitamins and serum total DDT in female Chinese textile workers suggest that studying toxins and nutrition separately does not offer an accurate view of how the factors intersect, according to researchers.
“Sufficient B vitamin status may decrease the toxic effects of DDT by better preparing the body to cope with environmental toxins and stressors,” Xiaobin Wang, MD, ScD, MPH, of Johns Hopkins Bloomberg School of Public Health, told Endocrine Today. “We have shown that women with high levels of DDT who also had sufficient levels of B vitamins had a better chance of getting and staying pregnant than those who were deficient in those vitamins.”
Xiaobin Wang
Wang and colleagues measured serum total DDT and plasma B vitamins of 291 women from Anhui, China, who were attempting to get pregnant.
From 1996 to 1998, the women were prospectively followed from the time they stopped contraception until clinical pregnancy (gestational age ≥42 days) or 12 months, whichever occurred first. Daily urinary human chorionic gonadotropin was used to identify early pregnancy loss.
The women were divided into categories based on B vitamin status (deficiency vs. sufficiency) and DDT concentration (high vs. low).
There were 385 conceptions, with 31% ending in early pregnancy loss, and 265 clinical pregnancies. Incidence rates of clinical pregnancy were lower in women with B vitamin deficiency and high DDT concentration (P<.05 for all) than women with adequate B vitamins and low DDT concentration.
In women with sufficient amounts of vitamin B12, DDT was not associated with clinical pregnancy incidence. Conversely, high DDT was linked to lower clinical pregnancy incidence (HR=0.44; 95% CI, 0.23-0.84) in women deficient in vitamin B12; further, the test for interaction was significant (P<.05).
For each interquartile distance increase in folate, the odds of early pregnancy loss decreased by 45% (95% CI, 21-62) in women with high DDT concentrations; the test for interaction was significant (P=.006).
“Our results provide suggestive evidence that vitamin B12 and folate sufficiency may help protect against adverse reproductive effects of DDT exposure,” Wang said. “Additional studies are needed to confirm our findings.”
Approximately one-third of miscarriages occur before 6 weeks, before a woman even recognizes her pregnancy, Wang noted. Although iron-folate supplements are provided to women seeking prenatal health care as a standard in many countries, supplementation typically occurs between 8 and 12 weeks of gestation, which researchers believe may be too late to prevent early pregnancy loss.
“Health care providers need to make sure women get adequate micronutrients, including B vitamins, in their diets not only during pregnancy, but before they even conceive,” Wang said in the release. “Otherwise, we may miss that critical window.”
DDT is still used to kill mosquitoes in many countries where malaria remains a serious public health concern, Wang said. The United States banned the pesticide in 1972; China, where the study was conducted, followed suit in 1984. DDT can remain in the body and environment for decades.
“In the United States, particular attention should be given to the growing number of reproductive age women who are immigrants from countries where DDT is still common or environmental residue of DDT remains high, and among low-income women whose diets may not include foods high in B vitamins, such as leafy green vegetables and beans,” Wang said. “Even women born in the United States may have DDT in their body systems, which may come from imported foods or even from local food grown in soil still contaminated with DDT.” – by Allegra Tiver
For more information:
Xiaobin Wang, MD, MPH, ScD, can be reached at Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe St., E4132, Baltimore, MD 21205-2179; email: xwang82@jhu.edu.
Disclosure: The research was supported in part by grants from the National Institute of Child Health and Human Development, the National Institute of Environmental Health Sciences and the Intramural Research Program of the National Institute of Environmental Health Sciences.
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