Cigarette smoke transforms healthy saliva into a deadly cocktail that can accelerate mouth cancer, according to new research in the British Journal of Cancer.
Normally, saliva provides a protective buffer between toxins and the lining of the mouth because it contains important enzymes that fight and neutralise harmful substances.
But the new research shows that the chemicals in tobacco smoke combine with saliva with devastating effect. They destroy the protective components of saliva – leaving a corrosive mix that damages cells in the mouth and can eventually turn them cancerous.
There are nearly 8,000 cases and 3,000 deaths from mouth cancer* in the UK every year – the main cause being smoking. The researchers in this study wanted to examine saliva's role in the development of mouth cancer.
The study recreated the effects of cigarette smoke on cancerous cells of the mouth. Half of the cell samples were exposed to cigarette smoke and the other half to the saliva and cigarette smoke mixture.
Cancerous cells were used in order to quickly assess whether the saliva and smoke mixture would speed the cancer's development.
The study revealed that the longer the mouth cells were exposed to the contaminated saliva, the more the cells were damaged.
Dr Rafi Nagler, based at the Technion-Israel Institute of Technology, who co-led the study, says: "Most people will find it very shocking that the mixture of saliva and smoke is actually more lethal to cells in the mouth than cigarette smoke alone.
"Our study shows that once exposed to cigarette smoke, our normally healthy saliva not only loses its beneficial qualities but it turns traitor and actually aids in destroying the cells of the mouth and oral cavity. Cigarette smoke is not only damaging on its own, it can turn the body against itself."