Can ulcers cause bad breath? Canker sores, yes. Stomach ulcers on the other hand...

Canker sores are an excellent sign that you may have bad breath. After all, these small, painful spots - also called aphthous ulcers - are caused by some of the same bacteria that lead to halitosis, gingivitis and periodontal disease. However, there's still disagreement over whether a different kind of ulcer causes oral odor.

You see, for decades, physicians have sworn up and down that one of the symptoms of stomach ulcers is halitosis. But whether or not that's true is unclear.

Consider a study recently published in the Journal of Breath Research. Its authors, a group of Dutch oral hygienists and gastroenterologists, asserted that the species of bacteria that causes gastritis - called Helicobacter pylori - doesn't give off the volatile sulfur compounds (VSCs) that lend bad breath its stench.

To bolster their argument, they tested 49 people (11 patients with stomach ulcers and 38 healthy controls) for halitosis and something called "stomach breath," which we're assuming is essentially the smell caused by a belch.

In all, they found that one ulcer patient and eight controls had oral odor, which is not a significant difference. However, that's not to say that some bad breath doesn't come from your tummy.

In fact, the man who proved that H. pylori causes stomach ulcers - Australian doctor and Nobel laureate Barry Marshall - reported halitosis as one of its primary symptoms. And he should know: In 1984, desperate for a test subject for H. pylori infection, he used the only one available - himself. Marshall drank 200 milliliters of a mix of peptone water and live bacteria.

The resulting stomach pain, ulcers, nausea and halitosis were reportedly tremendous. An antibiotic later cured him.

So it seems some ulcers might lead to oral odor (since canker sores certainly do). To reduce the halitosis caused by stomach ailments, a simple specialty mouth rinse should do. And of course, if you think you have gastritis, call your doctor immediately.