Does smelling certain foods make you sick? Scientists reveal how the immune system controls behavior

NEW HAVEN, Conn. — For people allergic to seafood, just the smell of it can make them pretty sick. The same thing can happen with people who have food poisoning after eating a specific meal. Scientists have known for some time now that the immune system plays a key role in how our bodies react to allergens in the environment, but now, a new study is revealing how the immune system also controls our behavior.

“We find immune recognition controls behavior, specifically defensive behaviors against toxins that are communicated first through antibodies and then to our brains,” says senior author Ruslan Medzhitov, the Sterling Professor of Immunobiology at Yale School of Medicine and an investigator for the Howard Hughes Medical Institute, in the media release.

Without solid brain-immune system communication, the brain can’t warn the body about environmental dangers that could possibly be harmful. According to this study, when this happens, the body doesn’t actively try to avoid threats, even when it should do so. This is a crucial finding for potentially changing these outcomes and helping to beat strong and lasting allergic reactions.

Sick woman blowing her nose, sneezing
(© Antonioguillem –

To conduct this study, Medzhitovs’ lab studied mice that were previously sensitized to be allergic to ova, which is a protein found in chicken eggs. They expected that the mice with allergies would avoid water laced with ova, which is indeed what happened. They even noticed that this aversion to ova-laced water lasted for months. Interestingly, the control mice were more inclined to prefer the water.

The team then looked at whether they could change the behavior of the sensitized mice by manipulating the immune system. Those allergic to ova lost their aversion if Immunoglobulin E (IgE) antibodies — which the immune system makes — were blocked. These antibodies typically release mast cells, a type of white blood cell that plays a significant role in communicating to the parts of the brain that control behaviors that reflect aversion or dislike. With IgE being blocked, the transmission of information to the brain was interrupted. This in turn made it so that the mice wouldn’t avoid the ova allergen anymore.

Medzhitov says that the findings show how the immune system may have evolved to help animals avoid certain ecological communities and provide a personal health advantage. Deepening the understanding of the nuances of the immune system could one day help stop severe reactions from happening in response toward allergens and pathogens within the environment.

The findings are published in the journal Nature.

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About the Author

Shyla Cadogan, RD

Shyla Cadogan is a DMV-Based acute care Registered Dietitian. She holds specialized interests in integrative nutrition and communicating nutrition concepts in a nuanced, approachable way.

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