As the fall approaches, so does flu season. But this year, you may have an extra defense against the flu: black tea.

Black Tea

Black Tea | A Girl With Tea at Flickr CC BY 2.0

According to researchers at Washington University in St. Louis, Missouri, the flavonoids in black tea (and red wine and blueberries) may work with a microbe in your intestines to better fight the flu and other infections.

Vocab refresher: a flavonoid is a group of plant-derived compounds that are also antioxidants. Tea has many.

The researchers at Washington University found that certain microbes in the gut can work with flavonoids to unleash a strong immune response to the flu—in mice at least.

“We were able to identify at least one type of bacteria that uses [flavonoids] to boost interferon, a signaling molecule that aids the immune response,” said the study’s senior author, Dr. Thaddeus Stappenbeck, a Conan Professor of Pathology & Immunology. “This prevented influenza-related lung damage in the mice,” he added, which can result in life-threatening complications like pneumonia.

While the researchers focused on mice, they did find a gut microbe in humans that they think will help people in the same way that it helps mice:

The microbe, Clostridium orbiscindens, interacts with flavonoids to create a metabolite that signals the immune system to beef things up. The metabolite is called desaminotyrosine, aka DAT.
The researchers found that mice who had both DAT and the flu experienced much less lung damage than mice with the flu who did not have DAT.

As the researchers put it, “Without DAT, influenza virus causes inflammation and severe disease.”

Conclusion: DAT helps fight the flu. And since humans can get DAT from things like black tea, they can experience the same flu-fighting properties as mice.

While the flavonoids in black tea are not going to prevent the flu, they can help your immune system fight off a serious complication. So this fall, in addition to getting a flu shot, stock your pantry with black tea!