Michigan researchers identified a food additive that may make flu vaccines less effective. When vaccinated mice ate food containing food additive tert-butylhydroquinone (tBHQ), it took them three days longer to recover from flu, compared to mice that ate food without the additive. In another experiment, unvaccinated mice eating the food additive had more virus RNA in their lungs, compared to mice who didn’t eat the additive. Researchers also found that the mice eating tBHQ had more inflammation and increased mucus production deeper in their lungs, suggesting the additive may make it more difficult to fight off flu.

The popular food additive is used to help stabilize fats and preserve foods. It’s commonly found in cooking oils and frozen meat products — particularly fish fillets — as well as processed foods like chips and crackers. Researchers aren’t sure exactly how tBHQ affects the body’s ability to fight flu, but they believe it may increase the activity of an immune system protein called Nrf2. An increase in activity of the protein may reduce the number of virus-fighting immune cells.

If you plan on checking ingredient labels to avoid the additive, that approach won’t help. Food manufacturers aren’t required to add it to labels. The truth is, the flu vaccine is not as effective as health officials want you to think it is. According to interim estimates from the CDC, the overall adjusted effectiveness of the 2018-19 flu vaccine against all influenza virus infection associated with acute respiratory illness needing medical attention was 47%. Among adults over 50, the vaccine had a mere 24% effectiveness against all influenza types, and an 8% effectiveness against influenza A(H1N1)pdm09 infection, which was by far the most common type.

In addition to issues with its effectiveness, the flu shot also comes with a list of possible side effects. If you want to be protected from influenza, consider practicing immune system-boosting strategies that may help shield your body against flu-causing agents. Optimizing your vitamin D levels, increasing your intake of vitamins B1 and C, or taking zinc lozenges when initial flu symptoms appear are known to work better than vaccines in addressing the disease before it worsens.