Very common food additive may make flu symptoms even worse

8 Apr 2019

Image: © Monkey Business/

New research suggests that a food additive found in frozen meat, crackers and other products may make it harder for us to fight the flu.

Often left off the list of ingredients on a food item, an additive called tert-Butylhydroquinone (tBHQ) could be not only making your body more susceptible to developing the flu, but could also increase the severity of its symptoms.

That’s a claim made by a team of researchers from the Michigan State University, which presented its findings at the American Society for Pharmacology and Experimental Therapeutics annual meeting yesterday (7 April).

The research found a link between tBHQ exposure and reduced effectiveness of the seasonal flu vaccine through the effects on T cells, a vital component of the immune system.

“Our studies showed that mice on a tBHQ diet had a weakened immune response to flu infection,” said Robert Freeborn, a fourth-year PhD candidate at Michigan State University. “In our mouse model, tBHQ suppressed the function of two types of T cells, helper and killer T cells. Ultimately, this led to more severe symptoms during a subsequent flu infection.”

When a person is infected with the flu virus, helper T cells direct other parts of the immune system and help coordinate a response, while killer T cells hunt down the infected cells and clear them from the body.

In the study, mice with a tBHQ diet were found to be slower to activate both helper and killer T cells, resulting in a slower immune response to the flu.

“Right now, my leading hypothesis is that tBHQ causes these effects by upregulating some proteins which are known to suppress the immune system,” Freeborn said. “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.”

Hard to know if you are consuming tBHQ

Another major finding was that when the mice were reinfected with a different – but related – strain of the flu, those with the tBHQ diet had a longer illness and lost more weight. This, the research team suggested, suggests the additive impaired the ‘memory response’ that typically primes the immune system to fight a second infection.

The tBHQ additive is used by food producers to prevent spoilage, with a maximum allowed concentration of 200 parts per million in whatever products are sold for consumption. While it is unclear how much tBHQ is being consumed, estimates put it at almost double this concentration in the US, and as high as 11 times that in other parts of the world.

“It can be hard to know if you are consuming tBHQ, as it is not always listed on ingredient labels,” Freeborn said. “The best way to limit tBHQ exposure is to be cognisant about food choices. Since tBHQ is largely used to stabilise fats, a low-fat diet and cutting down on processed snacks will help reduce tBHQ consumption.”

Updated, 9.34am, 9 April 2019: This article has been amended to reflect that Robert Freeborn is based at Michigan State University, not University of Michigan.

Colm Gorey was a senior journalist with Silicon Republic