Chewing food properly is not just good for digestion, but can also improve the mouth's immune system and protect you against illness, according to a recent study. 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 the National Institutes of Health in the United States, shows that chewing food also plays an important role.

The team found that the chewing action stimulates a specific type of immune cell - the Th17 cell.

In the experiment, the team fed mice with food that was hardened, which needed more mastication. That stimulated an increase in Th17 cells in the mice.

Lead researcher Joanne Konkel said: "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.

"Research shows that the mouth has a different way of stimulating Th17 cells, not through bacteria but by mastication. Therefore, mastication can induce a protective immune response in our gums."

However, too many Th17 cells can lead to periodontitis, a serious gum infection that affects the soft tissue and bone around a tooth.

She added: "Because inflammation in the mouth is linked to the development of diseases, understanding the factors that regulate immunity at the oral barrier could lead to new ways to treat multiple inflammatory conditions."

XINHUA