12 January - 20 June 2016

Can endocrine-disrupting chemicals lower vitamin D levels?

Exposure to bisphenol A (BPA) and other endocrine-disrupting chemicals (EDCs) may reduce levels of vitamin D in the bloodstream, according to a new study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.

Exposure to bisphenol A (BPA) and other endocrine-disrupting chemicals (EDCs) may reduce levels of vitamin D in the bloodstream, according to a new study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.

Vitamin D is essential in maintaining calcium homeostasis and bone health.  It also has a broad role in human health with vitamin D receptors present in many organs and tissues.  Deficiencies of vitamin D are reported to be implicated in cardiovascular disease, autoimmune disorders, cancer, and diabetes amongst others. 

BPA and phthalates are found in numerous industrial and chemical products and are known as endocrine disruptors interfering with hormones in the body.  This current study by Johns et al. investigates the relationship between phthalate metabolites and BPA and serum total 25(OH)D.  The researchers examined data from 4667 adults who participated in the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2010.  Total urinary BPA and urinary phthalates were measured in spot urine samples.  The participants provided blood samples so their vitamin D levels could be measured.  Johns et al. analysed demographic questionnaire data and potential confounding factors, such as age, gender, body mass index and smoking.  They also examined past 30 day vitamin D supplementation use based on the participant’s response. 

After carrying out numerous statistical analyses, the scientists report that serum total 25(OH)D concentrations significantly differed by population characteristics.  Mean total 25(OH)D concentrations were significantly higher in females than in males.  Ethnic subgroups had significantly lower total 25(OH)D compared to non-Hispanic whites, with the lowest mean concentrations reported among non-Hispanic blacks. 

Johns et al. report that all analytes were found in at least 90% of the study participants with the exception of MEHP.  Di(2-ethylhexyl) phthalate (DEHP) metabolites were inversely associated with total 25(OH)D in the overall study population however the association was strongest in women. The strongest associations in the overall study population were for MEHP and MEHHP.  When the researchers divided the participants into quartiles, an increase in MEHP and MEHHP metabolites was associated with a 2.07% and 2.09% decline in total 25(OH)D respectively. A positive association was also observed between urinary MEP and total 25(OH)D in both the overall population and in women alone.  An interquartile range increase in urinary BPA was associated with 3.71% decrease in 25(OH)D in women. 

The authors state that their findings are consistent to a previous study by Erden et al. however currently only one study has investigated this relationship with BPA in humans.  Johns et al discuss potential mechanisms that may explain the inverse relationship reported.  This includes that both DEHP and BPA have been shown to inhibit the activity of the cytochrome P450 enzymes, which as well as being involved in steroid and/or thyroid hormone metabolism, are involved in the conversion of vitamin D to its active metabolite.

In conclusion the scientists state that their findings indicate that exposure to phthalates and BPA may alter circulating levels of total 25(OH)D in adults. They note that future studies are required to “elucidate these exact mechanisms.”

RSSL provides vitamin analysis in a wide range of matrices including drinks, fortified foods, pre-mixes and multi-vitamin tablets, including the analysis for Vitamin D2 and Vitamin D3.  For more information please contact Customer Services on +44 (0) 118 918 4076 or email enquiries@rssl.com

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