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Phthalates, BPA may reduce vitamin D levels
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Environmental exposure to phthalates and bisphenol A may alter circulating levels of total 25-hydroxyvitamin D in adults, according to findings from a recent cross-sectional study.
In an analysis of blood and urine samples from the National Health and Nutrition Examination Survey, researchers observed an inverse relationship between di-2-ethylhexyl phthalate (DEHP) metabolites and total 25-(OH)D, with the strongest association observed in women.
“This study provides additional evidence for the potential far-reaching impacts of exposure to common endocrine-disrupting chemicals, as well as the diversity of possible biological pathways involved in those impacts,” John Meeker, ScD, professor of environmental health sciences and senior associate dean for research at the University of Michigan School of Public Health, told Endocrine Today. “Given the widespread nature of these exposures and the important role vitamin D plays in the body, the public health impact could be quite large.”
Meeker and colleagues analyzed data from 4,667 adults participating in three cycles of NHANES (2005-2006; 2007-2008 and 2009-2010) who had complete data on urinary phthalate metabolites, urinary bisphenol A (BPA), urinary creatinine and serum 25-(OH)D. Researchers measured total urinary BPA and 15 urinary phthalate metabolites in spot urine samples. Besides analyzing individual metabolites, researchers also created a summary measure of the four metabolites that share DEHP as their parent compound (MEHP; MEHHP; MEOHP and MECPP). All participants completed in-home questionnaires and provided information on 30-day vitamin D supplement use.
Researchers found that metabolites of DEHP were inversely associated with total 25-(OH)D in the complete cohort and in sex-stratified models. An interquartile range increase in the molar sum of DEHP metabolites was associated with a 1.9% decrease (95% CI, –3.64 to –0.17) in total 25-(OH)D.
The strongest associations were observed for MEHP and MEHHP; interquartile range increases in each were associated with a 2.07% (95% CI, –3.62 to –0.52) and 2.09% (95% CI, –3.87 to –0.32) decline in total 25-(OH)D, respectively.
Researchers observed an inverse relationship between BPA and vitamin D levels in women only; an interquartile range increase in urinary BPA was associated with a 3.71% decrease in total 25-(OH)D (95% CI, –6.41 to –1.02).
“Future human health and animal studies should aim to confirm these findings as well as inform the exact mechanisms through which these chemicals may impact vitamin D,” Meeker said. “Research into the clinical and public health implications of these relationships is also needed.” –by Regina Schaffer
For more information:
John Meeker, ScD, can be reached at the University of Michigan School of Public Health, 1835 SPH 1, 1415 Washington Heights, Ann Arbor, MI 48109; email: meekerj@umich.edu.
Disclosure: The researchers report no relevant financial disclosures.
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