Bad Breath

Most bad breath starts in the mouth

Bad breath, or halitosis, most often comes from bacteria on the back of the tongue and in the gum pockets breaking down proteins into volatile sulfur compounds (VSCs), the gases responsible for the smell. A randomised controlled trial of 100 people tested a specific probiotic strain, Weissella cibaria, taken as a daily tablet for 8 weeks. Total VSC levels were significantly lower in the probiotic group than the placebo group by the end of the trial, alongside measurably better bad-breath scores.

Source: Improvement of halitosis by probiotic bacterium Weissella cibaria CMU: A randomized controlled trial

When the cause is further down, in the gut

Not all bad breath is oral in origin. A study looking specifically at idiopathic halitosis, bad breath with no obvious cause in the mouth, found something striking. Small intestinal bacterial overgrowth (SIBO), a condition where bacteria multiply excessively in the small intestine, was present in 74.69% of these patients, compared with just 3.03% of healthy people. After two months of a probiotic preparation, 80.17% of the SIBO-positive patients became SIBO-negative, and their bad breath improved alongside it. Researchers believe VSCs produced in the gut, rather than the mouth, can be absorbed into the bloodstream, carried to the lungs, and exhaled, an extra-oral route bad breath can take that mouthwash and brushing simply can't reach.

Source: Therapeutic efficacy of a probiotic preparation on idiopathic halitosis: a retrospective observational study

H. pylori is a separate, well-documented cause

H. pylori, the bacterium behind many stomach ulcers, produces the enzyme urease, which breaks urea down into ammonia and other compounds that can smell unpleasant on the breath. In one study of 58 dyspeptic patients with confirmed bad breath, 30 tested positive for H. pylori. Among those who received eradication treatment, most saw their breath's sulfide levels drop back down to normal, directly tying a specific gut infection to a specific improvement in breath.

Source: Halitosis and Helicobacter pylori: A Possible Relationship

What this means for you

Persistent bad breath despite good brushing, flossing, and tongue cleaning is worth raising with a dentist first, since gum disease and tongue coating are the most common causes and are usually straightforward to treat. If oral causes have been ruled out, and especially if bad breath comes with bloating, irregular bowel habits, or stomach discomfort, it's worth discussing a possible gut cause, such as SIBO or H. pylori, with a doctor. A specific probiotic strain only helps if it's also given the fibre and plant compounds it needs to establish itself, rather than just being swallowed and expected to work alone. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.