Concerns raised over safety of common food preservative
A new study is raising questions over the safety of a commonly used food preservative found in hundreds of products. It's suspected the compound, tert-butylhydroquinone (known as tBHQ or E319), impairs effective immune system activity and the researchers are calling for greater surveillance of the immunological effects of food additives.
“The pandemic has focused public and scientific attention on environmental factors that can impact the immune system,” says lead author on the new study, Olga Naidenko. “Before the pandemic, chemicals that may harm the immune system’s defense against infection or cancer did not receive sufficient attention from public health agencies. To protect public health, this must change.”
The new study, published in the International Journal of Environmental Research and Public Health, examined data from ToxCast, the Environmental Protection Agency’s toxicity screening database. ToxCast assays screen chemicals for hundreds of different cell responses.
As a food preservative tHBQ has been used for decades, with both European and US health authorities deeming the additive safe. In very high doses researchers have seen animals develop cancers, but in low concentrations it has been classified as non-carcinogenic. The United States Food and Drug Administration (FDA) currently allows no more than 0.02 percent of the oil or fat content in foods to contain tBHQ.
The main goal behind this new research was to use new scientific methods to investigate the effects of old, previously approved food additives. Scott Faber, from the Environmental Working Group – a non-profit organization sponsoring the new research – says it is a problem that the FDA does not re-evaluate previously approved food additives when new science becomes available.
“Food manufacturers have no incentive to change their formulas,” says Faber. “Too often, the FDA allows the food and chemical industry to determine which ingredients are safe for consumption. Our research shows how important it is that the FDA take a second look at these ingredients and test all food chemicals for safety.”
The study suggests the ToxCast data reveals a number of signs tBHQ influences immune activity. The researchers do, however, make clear these findings are based on animal and mechanistic studies. Further investigation needs to be done to better understand how this compound affects human immune parameters, including “defense against infection, anti-tumor immune responses, and autoimmune reactivity.”
The research may only offer preliminary conclusions but they are certainly not isolated or outlying ideas. An animal study published in 2019 found mice raised on a diet with tBHQ displayed impaired immune responses to influenza infections.
Robert Freeborn, a researcher from Michigan State University working on that 2019 study, suggested at the time it was plausible tBHQ was inhibiting the activity of two key immune T cells, and this mechanism could not only lead to more severe influenza infection but also reduce the protective efficacy of vaccination.
"Right now, my leading hypothesis is that tBHQ causes these effects by upregulating some proteins which are known to suppress the immune system," Freeborn noted in 2019. "Expression of these proteins, CTLA-4 and IL-10, was upregulated in two different models we use in the lab. However, more work is necessary to determine if upregulation of these suppressive proteins is indeed causative for the effects of tBHQ during influenza infection."
The research team behind this latest study is cautious to jump to any major conclusions about tBHQ but it is suggested the key takeaway is the lack of comprehensive work tracking the immunological effects of food additives. Surveillance for cancer-causing chemicals may be high but more work is needed to track how food additives can disrupt immune functions.
“From the public policy perspective, the discovery of impacts on human health of substances that have long been used in consumer products and food products suggests that the pre-market safety evaluation of these substances was inadequate,” the researchers conclude in the study. “We recommend that immunotoxicity testing should be prioritized in order to protect public health, and immunotoxicity analysis should be, in our estimate, an integral part of chemical safety assessment.”
The new study was published in the International Journal of Environmental Research and Public Health.
Source: Environmental Working Group