A study published in the Journal of the American College of Nutrition shows that consuming mushrooms may improve the immune system.
In this study, the researchers used shiitake mushrooms, which are native to Asia and are cultivated for their culinary and medicinal value. The researchers gave 52 healthy adults, aged 21–41, a four-week supply of dry shiitake mushrooms. Participants took the mushrooms home, cleaned them, and cooked them. Then they ate one, four-ounce serving of mushrooms each day during the experiment.
To be eligible for the study, the participants could not be vegans or vegetarians. They also could not drink tea, take antioxidant supplements or probiotics before the study. During the study, they could not consume more than 14 glasses of alcoholic beverages per week or eat more than seven servings of fruits and vegetables per day. As the researchers explained it, this is because fiber, tea, and probiotics help the body's immune system, and they didn't want to start the study with people who already had a strong immune system. Additionally, excess alcohol could suppress immunity.
Through blood tests before and after the experiment, the researchers saw better-functioning gamma delta T-cells and reductions in inflammatory proteins. Eating a shiitake mushroom every day produced beneficial changes in the immune system among study participants, according to Sue Percival, University of Florida food science and human nutrition professor. "We're enhancing the immune system, but we're also reducing the inflammation that the immune system produces," said Percival.