Tobacco smoking can dramatically change the balance of bacteria in the mouth, affecting a person's risk of mouth, lung and digestive system diseases, a new report revealed.

There is good news: the oral microbiome balance can be restored if people quit smoking.

In the study featured in the International Society for Microbial Ecology Journal, researchers examined the mix of about 600 bacterial species in the mouths of more than 1,200 individuals in the United States.

All participants were 50 years old and above, and included people who never smoked, people who currently smoke, and people who have kicked the habit.

The research team found that current smokers had experienced a significant increase in growth for more than 150 oral microbiome species, while 70 bacterial species experienced decreases in growth.

- Proteobacteria species

Proteobacteria help break down toxic chemicals that people get from smoking, researchers said.

The number of Proteobacteria species in the mouth of smokers were found at less than 5 percent of overall bacteria, compared the 12 percent rate among non-smokers.

- Streptococcus

Smokers possessed 10 percent more species of Streptococcus in their mouths, compared with non-smokers. These species apparently promote the decay of teeth.

Possible Implications

Senior investigator Jiyoung Ahn of NYU Langone Medical Center said the study is the first to suggest that smoking has a significant impact on a person's oral microbiome.

Previous studies have linked imbalances of microbiome in the gut to immune disorders such as Crohn's disease and gastrointestinal cancers. Some experts say that more than 75 percent of cancers in the mouth are tied to smoking.

However, Ahn said it remains to be seen whether oral microbiome differences due to smoking contribute to the risk of mouth cancer, as well as the risk of diseases in the gut and lungs.

Bouncing Back

Ahn and her colleagues found that the number of mouth bacteria seemed to return to normal after a person stops smoking completely.

All former smokers who did not smoke for the past decade possessed the same balance of oral microbiome as nonsmokers.

But the research team cautions that they have yet to find out how long it takes for the oral microbiome to become balanced again.

In the meantime, Ahn and her team plans to investigate how smoking-related changes could influence the risk for cancer of the mouth and other parts of the body.

Photo : Chris Vaughan | Flickr