LONDON, Jan. 19 (Xinhua) -- Chewing food properly is not just good for digestion, but can improve mouth's immune system protecting you against illness, according to a study released Thursday by The University of Manchester.

Scientists have known that food nutrients can contribute to a healthy immune system in the mouth, but the study, led by researchers from The University of Manchester and National Institutes of Health in the United States, shows that chewing food also plays an important role.

The team found that when you are chewing, the action will stimulate a specific type of immune cell -- the "Th17" cell.

In their experiment, the team changed the hardness of the food fed to mice, which caused more mastication. That stimulated the increases in Th17 cells in mice.

"The immune system performs a remarkable balancing act at barrier sites such as the skin, mouth and gut by fighting off harmful pathogens while tolerating the presence of normal friendly bacteria," says one of the study authors Joanne Konkel from The University of Manchester.

"Our research shows that, unlike at other barriers, the mouth has a different way of stimulating Th17 cells: not by bacteria but by mastication. Therefore mastication can induce a protective immune response in our gums," says Konkel.

However, it is not always good to have too many Th17 cells, which can lead to periodontitis.

Nontheless, "because inflammation in the mouth is linked to development of diseases all around the body, understanding the tissue-specific factors that regulate immunity at the oral barrier could eventually lead to new ways to treat multiple inflammatory conditions," adds Konkel.