We all know that certain specific foods and beverages - like garlic, onions, leeks, meat, milk, coffee and alcohol - can cause halitosis. But what are the connections between these ingredients? Are there, more generally, whole culinary categories or entire diets that are most likely to make your mouth reek?
That's exactly what Jukka H. Meurman, a dentist at Finland's University of Helsinki, wanted to find out. He conducted a review of oral diseases and their "functional foods" (i.e. the diets they're linked to), and, sadly, didn't turn up much.
Meurman stated that most bad breath comes from oral bacteria, which feast on the foods you eat and pump out foul-smelling compounds. He noted that three species - Treponema denticola, Porphyromonas gingivalis and Tannerella forsythia - cause both halitosis and gum disease.
What food types do such bacteria prefer? Meurman pointed to carbohydrates, but had no data to back this up.
"Fermentable carbohydrates in diet which in general increase oral microbial colonization should be avoided in cases with bad breath," he said. "However, no controlled studies exist on the effect of dietary regimens on halitosis."
This is a problem, since carbohydrates are not the only food type that seems to make bad breath worse. High-protein, low-carb eating regimens - like the Dukan and Atkins diets - are well-known for causing terribly stinky oral odor, the kind that only oxygenating toothpastes and alcohol-free mouthwashes can relieve.
Likewise, fatty and oily diets provide sustenance for oral microbes, while produce-based regimens can cause a stink by way of the smelly compounds found in certain vegetables (like the allyl methyl sulfate in garlic, or the methyl mercaptan in cabbage).
Overall, it appears that any diet will cause halitosis, which is why it's best to eat well-rounded meals and rely on specialty breath fresheners to prevent oral odor.