Common Food Additive May Impair Immune Response to Flu Vaccine

New research suggests a common food preservative could weaken the effectiveness of the flu vaccine by altering the body’s immune response.

Scientists from Michigan State University studied the impact the food additive tert-butylhydroquinone (tBHQ) had on vaccine effectiveness in mice and found that the preservative often found in frozen meats, cooking oils, and processed foods, caused the vaccine to be less effective.

“If you get a vaccine, but part of the immune system doesn’t learn to recognize and fight off virus-infected cells, then this can cause the vaccine to be less effective,” says Robert Freeborn, a doctoral student in a university news release. “We determined that when tBHQ was introduced through the diet, it affected certain cells that are important in carrying out an appropriate immune response to the flu.”

Freeborn and Cheryl Rockwell, PhD, an associate professor in pharmacology and toxicology at Michigan State University in East Lansing, used several flu strains including H1N1 and H3N2 to evaluate the impact tBHQ had on CD4 and CD8 T cells.

They found that there was an overall reduction in the number of CD8 T cells in the lung, as well as fewer CD4 and CD8 T cells that were able to identify the flu virus, in those mice that had been given levels of tBHQ in their food comparable to human consumption.

“I think this study suggests that low doses of tBHQ can impact host defense to influenza in mice which suggests the need for more studies to determine whether tBHQ may have similar effects on host defense in humans,” Rockwell told Drug Topics.

tBHQ was also found to slow the initial activation of T cells in the mice. This reduced the animal’s ability to fight infection and resulted in the virus running “rampant” in the mice until the cells became fully activated, the researchers said.

In a second phase of the study, researchers found that tBHQ also negatively impacted the immune system’s ability to remember how to respond to the flu virus.

Rockwell said previous research has used tBHQ in the lab to activate a transcription factor protein called Nrf2, but researchers aren’t sure yet why the food additive appears to block the immune system.

Some in vitro studies, done with isolated immune cells in a dish, have shown that activation of Nrf2 can cause many similar effects. Further research is needed, however, to confirm that connection.

The next step for researchers will be to repeat the studies in mice that are deficient in Nrf2 to determine whether the protein is critical to the effects of tBHQ on a host’s defenses.

Rockwell said if the researchers are able to determine the human body responds the same way as the mice in the study, FDA regulations on tBHQ labeling may need to be revisited .