New Study Shows How BPA Is Linked to Type 2 Diabetes
Researchers in Spain have found that even small doses of bisphenol-A (BPA), which is found in many consumer products, can cause a spike in insulin levels by acting as an estrogen. Repeated exposure to high levels of insulin can cause the body to gradually become desensitized to it, which may lead to obesity and type 2 diabetes. The researchers recently published their findings in the journal PLoS ONE.
They observed that bisphenol-A at a 1 nM (0.000000001 Molar) concentration acts on estrogen receptor β (ERβ) and induces a rapid release of insulin from mouse beta cells (β-cells), Angel Nadal, corresponding author of the study, tells me in an e-mail. Nadal, a professor of physiology at the Universidad Miguel Hernández in Spain, mentions that 1 nM is consistent with the usual concentration of BPA found in human serum.
What makes this work significant, says Bruce Blumberg, a professor of cell and developmental biology and pharmaceutical sciences at the University of California Irvine who was not involved in Nadal’s study, is that the scientists were able to determine that bisphenol-A causes type 2 diabetes in mice by acting on ERβ. No one had been able to identify this mechanism before.
Nadal and his team simultaneously carried out the same experiment on cells from so-called “wild-type” or normal mice with ERβ, and on cells from mice that lacked ERβ. They found that BPA affected insulin levels in β-cells from wild-type mice, but not those from mice whose cells lacked ERβ. This evidence makes the detrimental effects of BPA, and its link to type 2 diabetes, much more difficult to argue with, Blumberg tells me.
The Huffington Post recently discussed the implications of these new findings.
The investigators also found that the same 1 nM concentration of bisphenol-A causes the release of higher levels of insulin in human β-cells and pancreatic islets of Langerhans compared to those released in mice.
For his part, Nadal said, “What surprised me was that such a low dose of bisphenol-A had such a strong effect on human β-cells.”
What Can I Do About BPA Exposure?
Unfortunately, though you can minimize BPA exposure, it is difficult to reduce exposure to zero, says Blumberg. He mentions that most people believe that you take in the chemical orally, for example, via water bottles. But he says, exposure is also possible by contact through the skin. For example, Blumberg mentioned that thermal paper, on which cash register receipts are printed, contains BPA.
In addition to water bottles, other examples of bisphenol-A-containing consumer goods include polycarbonate tableware, food storage containers, and baby bottles. Bisphenol-A can be released from plastic after being exposed to high temperatures or acidic or basic media, Nadal says, so we should avoid these products as much as possible.
However, he points out that air, dust, and water are other possible sources of exposure. “In my opinion, stricter standards about safe levels of BPA exposure are necessary,” he says.