The human mouth is, on average, home to some 600 different species of bacteria that can either be beneficial to us, as is the case with bacteria that give our foods their taste and scent, or very harmful, as is the case with Helicobacter pylori, the culprit behind stomach ulcers and gastric cancer. Recently, researchers managed to establish that H. pylori also lives in the mouth, producing volatile compounds, which create bad breath.
 

"We wanted to determine whether the bacteria can cause bad breath, so we tested patients complaining of halitosis for the presence of H. pylori. Halitosis is a common problem in humans, and bad breath is largely caused by periodonitis, tongue debris, poor oral hygiene and badly fitted fillings. Bacteria produce volatile compounds that smell unpleasant, including hydrogen sulphide, methyl mercaptan and dimethyl sulphide. Doctors often measure the levels of these compounds to diagnose the problem. Gastrointestinal diseases are also generally believed to cause halitosis," said Japanese scientist Dr. Nao Suzuki, at the Fukuoka Dental College in Fukuoka.

 
Statistics suggest that some 80 percent of people worldwide carry this bacterium in their mouths, which makes halitosis one of the most widespread problems in human history. Fighting against it is not simple, doctors say, as killing a specific type of bacteria amidst hundred others is extremely difficult. Killing all bacteria in the mouth could cause inconveniences for people, as saliva and oral mucosa could be irretrievably affected.
 

In approximately 6.4 percent of 326 Japanese test subjects suffering from bad breath, Suzuki's team found that 21 had H. pylori in their mouths. Similar results were discovered in patients suffering from periodontal diseases – 16 of 102 patients had the bacterium, which amounts to some 16 percent. The researchers say that these results, although coming from analyses done on few test subjects, can be considered as representative for entire populations, worldwide.
 

"Although the presence of H. pylori in the mouth does not directly cause bad breath, it is associated with periodontal disease, which does cause bad breath. We now need to look into the relationship between H. pylori in the mouth and in the stomach. We hope to discover the role of the mouth in transmitting H. pylori stomach infections in the near future," concluded Suzuki.