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Can a common food preservative harm the immune system?

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A new study investigated food preservatives and the immune system. Irina Marwan/Getty Images
  • A recent study has assessed the harmful effects of chemical food additives and food contact substances on the immune system.
  • The study compared laboratory toxicology testing (ToxCast) results with data from previous animal tests and epidemiological studies.
  • The ToxCast results and available animal study data confirmed that a common food preservative called tert-Butylhydroquinone (TBHQ) might negatively affect immune system functioning.
  • The study affirmed the need for updated research and a thorough Food and Drug Administration (FDA) review of chemical food additives and food contact substances to assess immune system toxicity and protect public safety.

Various common chemicals may harm the immune system, causing it to malfunction. This is known as immunotoxicity. These harmful effects may be temporary or permanent.

Possible immunotoxic effects include:

  • hypersensitivity
  • chronic inflammation
  • immunosuppression, or an impairment of the body’s ability to fight off infections
  • immunostimulation, which can cause tissue damage through immune responses
  • autoimmunity

In particular, if an immunotoxic substance causes the body to produce fewer antibodies, it can have an effect on the fight against active infections and the protection against future ones.

The FDA currently require immunotoxicity testing for food additives. However, most food additives received approval decades ago, and the FDA do not mandate updated testing on previously approved additives.

TBHQ is a common preservative that manufacturers use to prolong their products’ shelf lives.

According to the Environmental Working Group (EWG), it is present in almost 1,250 processed foods, including Cheez-It crackers, Pop-Tarts, Reese’s Peanut Butter Cups, and Little Debbie Swiss Rolls.

However, this chemical has had immunotoxic effects in animal studies.

Chemicals may also leach from packaging or food processing equipment into food. Some bags, boxes, and food wrappers are coated with per- and polyfluoroalkyl substances (PFAS).

PFAS-based materials are also common in non-stick coatings on cookware, gaskets in food processing equipment, and repeat-use plastics.

The FDA require immunotoxicity testing only for food contact substances with a high daily exposure. The immunotoxicity of many food additives and food contact substances is largely unknown.

The Environmental Protection Agency (EPA) use high throughput in-vitro testing in their ToxCast program. This type of testing exposes living cells, proteins, or biological molecules in a laboratory environment to chemicals to assess and identify any potential toxic effects. This potentially limits the need for animal testing.

The sparsity of current immunotoxicity data prompted the researchers from the EWG to conduct a study to evaluate the immunotoxic effects of common food additives and food contact substances. They also assessed the utility of ToxCast data in screening for immunotoxicity.

Lead study author Dr. Olga Naidenko, Ph.D., EWG’s vice president for science investigations, emphasizes the urgency of this research:

“The pandemic has focused public and scientific attention on environmental factors that can impact the immune system. 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 researchers analyzed a total of 63 direct food additives present on more than 10 product labels sold in the U.S. in 2018–2020. They also specifically assessed nine identified PFAS that migrate from food packaging to food.

The findings now appear in the International Journal of Environmental Research and Public Health.

The study evaluated these substances, concentrating on those with the highest number of active ToxCast assays. It focused further analyses on those substances with activity toward multiple immune-related targets and proteins involved in immune response, inflammation, and defense mechanisms.

The study compared the results of high throughput ToxCast data with available data from animal and epidemiological studies.

Strong data from both ToxCast testing and immunological laboratory animal studies indicate that TBHQ may cause immune functioning changes.

However, ToxCast screening yielded data that did not always agree with existing data: There were cases wherein ToxCast data conflicted with previous data or indicated risks that previous data had not found.

Three different situations happened with the food colorant FD&C Red 3 and PFAS such as perfluoroundecanoic acid (PFUnDA) and perfluorooctanoic acid (PFOA).

In the study, the ToxCast data indicated that FD&C Red 3 affected multiple immune parameters, but the researchers did not find reference to any animal or epidemiological study into the immunotoxicity of this food colorant.

ToxCast, laboratory animal, and human study data demonstrated that PFUnDA affected multiple immune parameters and increased immune suppression risk.

However, the ToxCast data did not show strong activity for immune targets with PFOA, whereas animal and human studies demonstrated immunosuppressive effects.

The study attributed the lack of consistency in the findings to a lack of understanding of the exact mechanism of PFAS toxicity. The limitations of currently available high throughput testing to capture the full extent of the potential mechanism for immunotoxicity may also have had an impact.

The researchers conclude that both ToxCast and study data suggest that chemicals indirectly or directly added to foods, such as THBQ and PFAS, may adversely affect immune system functioning.

The EWG stress that the FDA should prioritize and integrate updated immunotoxicity testing to identify harmful chemicals into standard safety assessments to protect public health and well-being.

Scott Faber, senior vice president for government affairs at the EWG, adds, “Food manufacturers have no incentive to change their formulas. Too often, the FDA [allow] 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.”

What do you think?

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