First-time finding: Risk of BPA on intestinal health found amid rising bowel disease cases

11 Jul 2018 --- Dietary exposure to BPA – found in polycarbonate plastics often used in making containers to store food and beverages – can worsen the symptoms of Irritable Bowel Disease (IBD), a study published in Experimental Biology and Medicine has found. IBD can be further exacerbated by the hormone estrogen, and BPA is a known synthetic estrogen.

“This is the first study to show that bisphenol A (BPA) can negatively impact gut microbial amino acid metabolism in a way that has been associated with irritable bowel disease,” says Jennifer DeLuca, First Author of the study.

BPA is an industrial chemical that has been used to make certain plastics and resins. The chemical is found in polycarbonate plastics often used in making containers to store food and beverages, such as water bottles. It is also found in epoxy resins used to coat the inside of metal products, such as food cans, bottle tops and water supply lines. In addition, some dental sealants and composites contain BPA.

The focus on BPA was landed on due to its hormonal composition and, amid increasing IBD cases in industrialized countries, Allred explains, the researched was warranted. Furthermore, “BPA has been previously shown to alter gut microbes similarly to the way the gut microbiota is altered in IBD patients,” adds Allred.

The researchers note that previous research has shown that BPA can seep into food or beverages from containers made with it and may have possible health effects on the behavior, the brain and prostate glands of fetuses, infants and children.

Influence on IBD
This study sought to detect the impact of BPA on irritable bowel disease (IBD), which is a complex collection of conditions that include ulcerative colitis and Crohn's disease. 

“While the causes of IBD have not yet been determined, environmental exposures such as diet, smoking, infections, altered gut microbiome and toxins or pollutants are risk-factors for development and relapse,” says Dr. Kimberly Allred, Professor at the Nutrition and Food Department and study author. “In this study, we wanted to focus on what effect BPA may have on IBD.”

The researchers investigated the ability of BPA to exacerbate colonic inflammation and alter microbiota metabolites derived from aromatic amino acids in an acute dextran sulfate sodium-induced colitis model in mice.

“We assessed body weight and fecal consistency in addition to inflammation, injury and nodularity of the colon,” he explains. “We also analyzed changes in microbiota metabolite levels derived from aromatic amino acids reflecting changes in the gut microbiome.”

Essentially, exposure to BPA also increased the levels of several compounds that drive inflammation in the colon, Allred says.

“These types of studies are important to provide initial evidence that we need to better understand how things in the environment influence our risk of getting or worsening symptoms of diseases like IBD and how we can reduce that risk,” Allred concludes.

BPA: What’s the risk?
BPA is a synthetic hormone – estrogen – and high doses of the chemical have been linked to fertility problems such as male impotence. However, some reports do say that BPA in low doses is not harmful to humans.

Although this is the first study to associate BPA and the gut microbe in a way that is associated with IBD, BPA has had bad press for some time. For example, The US Food and Drug Administration (FDA) banned BPA in baby bottles in 2012 and prohibited it in infant formula packaging in 2013 while the EU also implemented a ban on BPA use in baby bottles. The EU further banned the use of BPA in thermal paper (receipts) in 2016. The restriction concerns thermal paper containing BPA in a concentration equal to or above 0.02 percent by weight. 

However, earlier this year a study which linked low dose exposure from BPA with a threefold increase in combined benign breast tumors and breast cancer in lab rats was released. The two-year study, a research collaboration called CLARITY-BPA, was coordinated by the interagency National Toxicology Program (NTP), the National Institute of Environmental Health Sciences (NIEHS), and the FDA with a goal of studying the range of potential health effects from BPA exposure. In addition to the links to breast cancer, the researchers also found significant effects on the heart and reproductive system. 

However, despite these findings, the FDA still issued a statement asserting that the study showed “minimal” health hazards. In reaction, the Environmental Working Group said, “This has been the FDA’s posture for more than a decade. Defending the safety of BPA exposures while independent scientists report BPA is toxic to the brain, thyroid and reproductive systems.”

A further issue comes to the fore when the possible replacement for BPA comes under discussion as the potential replacement chemical, named bisphenol (BPS), has been criticised as being just as harmful as its predecessor. 

A European Food Safety Authority (EFSA) spokesperson tells NutritionInsight on the topic: “In 2016 EFSA has received a new mandate to re-evaluate the safety of BPA: The first part of the mandate, i.e. to pre-define the assessment strategy, was finalized in December last year. At the moment EFSA is engaging in a new evaluation of all the new scientific evidence available since January 2013 in order to establish a full TDI for the substance and to resolve the uncertainties about possible low dose effects of BPA identified in the EFSA opinion published in 2015.”

Despite discrepancies on the role of BPA in human health, guidelines for the use of the chemical in packaging goods have remained stable. However, a range of brands have released BPA-free packaging which does help to ease the qualms of consumers confused by regulatory and scientific clashes.

By Laxmi Haigh