A meta-analysis suggests that certain probiotic bacteria can alleviate stubborn bad breath. Accordingly, the intake of probiotics has a beneficial effect on the oral flora and reduces the production of sulphurous, foul-smelling compounds through anaerobic degradation processes. In the studies, this reduced the perceptible bad breath of the test subjects and also the objectively measurable content of sulfur compounds in the exhaled air.
Around a third of all people suffer from persistent bad breath, medically known as halitosis. In 85 to 90 percent of cases, it is caused by the activity of bacteria on the tongue, in plaque, on the gums or between the teeth. As these microbes break down food debris and other organic matter, they produce strong-smelling sulfur-containing compounds such as hydrogen sulfide (H 2 S), methyl mercaptan (CH 3 SH), and dimethyl sulfide (C 2 H 6 S). Poor oral hygiene, periodontitis and smoking promote this.
But how do you get rid of halitosis? Mechanical cleaning of the tongue and tooth space can often help, as with professional tooth cleaning, but this usually only brings temporary relief. Chemical agents to combat the causative bacteria in the form of antibacterial mouthwashes and antibiotics are also used. However, they have the disadvantage that they also deplete beneficial oral bacteria.
However, a gentler and more sustainable solution could be probiotics, as a meta-analysis now suggests. Beneficial bacteria such as Lactobacillus salivarius or L. reuteri, Streptococcus salivarius or Weissella cibaria are taken in the form of chewing gum or lozenges.
These bacteria are typically found in yogurt, sourdough, miso, and other fermented foods. When taken as probiotics, they should displace the microbes in the mouth that produce the foul-smelling sulfur compounds – at least that’s the idea behind it.
Researchers led by Nengwen Huang from the University of Sichuan in China have now investigated whether this works. To do this, they evaluated seven studies in which a total of 278 test persons with bad breath received a probiotic preparation against bad breath or a placebo once or twice a day. The effectiveness was primarily determined based on the concentration of sulfur compounds in the exhaled air and the subjective smell. The researchers also assessed the plaque on the tongue and teeth.
The result: Taking probiotics brought significant improvements in halitosis compared to placebo treatment. The subjectively perceptible bad breath decreased by more than half in the probiotics group, both in the short term and in the long term. The objectively measurable content of foul-smelling sulfur compounds in the exhaled air also decreased. This was particularly evident in the case of hydrogen sulfide, the proportion of which decreased by an average of 73 percent, as Huang and his colleagues found.
“These results suggest that probiotic therapy can reduce bad breath and therefore have positive effects against halitosis,” state Huang and his team. They attribute this effect to the fact that the probiotic bacteria have a positive effect on the oral flora and inhibit the breakdown processes that produce the foul-smelling sulfur compounds. “The significantly lower levels of volatile sulfur compounds suggest that the activity of anaerobic oral bacteria decreases as a result of the probiotic treatment,” explains the team.
However: While the subjective improvement in bad breath when taking the probiotics also lasted in the long term, this was not the case with the content of sulfur compounds in the exhaled air: They increased again after about four weeks.
According to the scientists, this could be closely related to the fact that the administration of the probiotic bacteria has a positive effect on the microbial degradation processes in the mouth, but does not eliminate their causes. Because the probiotic therapy had no effect on the oral and dental plaque, as their evaluation showed.
Overall, however, the results are promising enough to further research this therapy against bad breath: “More high-quality, randomized clinical studies are needed to verify the results and to prove the effectiveness of probiotics against halitosis,” says the team. (BMJ Open, 2022; doi: 10.1136/bmjopen-2022-060753)
This article was written by Nadja Podbregar
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The original of this article “Bacteria against bacteria could eliminate bad breath in the long term” comes from scinexx.