A common food additive may make the flu vaccine less effective

ORLANDO — A common food additive may make it more difficult to fight the flu.

Vaccinated mice that got food containing the additive, tert-butylhydroquinone (tBHQ), took three days longer to recover from the flu than mice that ate tBHQ-free food. The unpublished result suggests the common additive may make flu vaccines less effective, toxicologist Robert Freeborn of Michigan State University in East Lansing reported April 7 at the 2019 Experimental Biology meeting.  

The additive helps stabilize fats and is used as a preservative for a wide variety of foods, including some cooking oils, frozen meat products — especially fish fillets — and processed foods such as crackers, chips and other fried snacks. Food manufacturers aren’t required to put the ingredient on labels, so “it’s hard to know everything it’s in,” says Freeborn.

In separate experiments, unvaccinated mice eating tBHQ in their food had more virus RNA in their lungs than mice that didn’t eat it. The tBHQ eaters also had inflammation and increased mucus production deeper in their lungs than usual, Freeborn and colleagues found.  

The researchers don’t know exactly how the additive hampers flu fighting, but it may be because it increases activity of an immune system protein called Nrf2. Increased activity of that protein might reduce the number of virus-fighting immune cells in the mice. That possibility remains to be tested.