FRIDAY, March 11, 2005 (HealthDay News) -- If you've tried mints, mouthwash and toothpaste but your breath still offends, maybe you should skip the oral hygiene aisle. Next time, try the dairy case.
In a small study, Japanese researchers have found that eating traditional, sugarless yogurt reduces the malodorous compounds that cause bad breath. It also cuts down on plaque and gingivitis, they discovered.
The study, funded in part by a major Japanese yogurt maker, was presented March 10 at the International Association for Dental Research annual meeting, in Baltimore.
Halitosis, or bad breath, is caused by anaerobic bacteria that breed on the back of the tongue, producing volatile sulfur compounds. One of those compounds, hydrogen sulfide, is the stuff that causes your breath to smell like rotten eggs.
Lead author Kenichi Hojo and colleagues from Tsurumi University in Yokohama, Japan, decided to investigate yogurt because of its effects in preventing gastrointestinal problems and research indicating that regular yogurt consumption reduces the risk of dental decay.
"We are thinking that yogurt must be good for oral health, also," said study co-author Nobuko Maeda, a professor of microbiology at the university.
Researchers recruited 24 volunteers. Each person received identical instructions for oral hygiene, diet and medication intake. In the initial phase of the study, participants were asked not to consume yogurt or products containing streptococci and lactobacilli, such as cheese and pickled vegetables. During the second phase, they consumed 90 grams of yogurt, or a little more than 3 ounces, twice a day for six weeks.
Researchers collected samples from the participants' saliva and tongue coatings, and measured volatile sulfide compound concentrations in the air of people's mouths. Those measures showed that, at six weeks, hydrogen sulfide levels decreased in 80 percent of volunteers who had bad breath.
"So we thought two yogurts per day did work for improving (bad breath)," Maeda said.
In addition, plaque and gingivitis was significantly reduced in people with bad breath after the yogurt-intake phase of the study, compared with the initial phase when they did not consume yogurt.
However, the authors said there were no noteworthy differences in the number of oral bacteria in the mouths of people before and after eating yogurt.
Bruce J. Paster, senior staff member in the department of molecular genetics at The Forsythe Institute in Boston, suggested the authors may nothave looked for all the bacteria that were present. "Typically, the bacterial microbiota and their end products are the culprits for the bad breath," hesaid.
"In theory," he added, "their hypotheses may be valid. For example, the odor-causing species may have been replaced by some 'good' species in the yogurt."
Research participants consumed yogurt made especially for the study, Maeda said. As with other yogurts, the starter culture consisted of a combination of Streptococcus thermophilus and Lactobacillus bulgaricus. What differed was the strain of bacteria they used, she said.
The yogurt maker that helped fund the study hopes to make its product commercially available this fall, she added.
The American Dental Association has information on treating bad breath.