Scientists Test Oral Bacteria Transplants for Bad Breath and More

Bad breath affects one in four people, and bad bacteria living in your mouth are to blame. Here is how you can keep that smell at bay and stay fresh.

Would you swallow a stranger's saliva as medicine? It sounds gross, yet brave volunteers are already doing this. They participate in clinical trials testing oral microbiome transplants. This process moves bacteria from healthy mouths into patients with problems. Scientists hope it could be a major medical breakthrough.

Current trials target tooth decay and halitosis. They also look at oral mucositis. That painful condition causes sores inside the mouth after cancer treatments like chemotherapy or radiotherapy. Some experts believe this simple procedure might one day lower the risk of serious diseases, including cancer itself.

Many know the gut microbiome well. It is the soup of organisms in your intestines that keeps you healthy. Doctors test faecal transplants to treat issues like irritable bowel syndrome. Now, scientists are turning their attention to the mouth. Dr Lindsey Edwards from King's College London says the oral microbiome could be just as important as the gut version.

Friendly bacteria coat your teeth, gums, tongue, and cheek lining. They form a barrier against harmful pathogens. These bad germs cannot replicate or enter your bloodstream if this shield holds strong. However, recent studies show damage to this balance can cause widespread inflammation. It may also lead to conditions like cancer.

A study published in the journal RMD Open in July found an imbalanced oral microbiome links to osteoarthritis. Researchers from China, Australia, and the UK examined saliva from 52 people with hand arthritis. This disease affects nearly 1.5 million Britons. They compared these samples against those from healthy volunteers.

Patients with hand arthritis showed significantly higher levels of Trichococcus. This bug is common in sewage. It can colonise your mouth if you pick it up from contaminated surfaces. The more of this organism present, the worse the joint pain and inflammation became. Experts think the immune system attacks these bugs. This triggers low-level, chronic inflammation that breaks down cartilage in the joint.

This is not the only link between a bad oral microbiome and illness. Poor dental hygiene or overusing mouthwash can disrupt the balance. Research published in BMC Microbiology in July showed early-onset bowel cancer patients had different oral bacteria profiles than healthy peers. They had higher concentrations of certain bacteria. Crucially, they possessed a smaller variety of bugs overall. Diversity is key to health for both gut and mouth microbiomes.

Scientists are still debating if bacterial imbalance fuels the cancer or if the disease drives bacterial changes. Either way, checking saliva for a bacterial profile could screen for early-onset bowel cancer before symptoms appear. This form of cancer often strikes before age 50, and cases are rising fast.

Researchers at King's College London have uncovered significant distinctions between the oral microbiomes of healthy individuals and those suffering from Parkinson's disease, a condition currently affecting roughly 160,000 people across the UK. The findings appeared in Gut Microbes last year. They indicate that patients with Parkinson's who have developed dementia as a secondary complication show higher concentrations of what researchers call 'harmful' bacteria compared to those without dementia or healthy controls. This form of dementia hits up to half of all Parkinson's patients. These microbes migrate from the mouth down into the gut, where they spark toxin release that can wound the stomach, ignite widespread inflammation, and potentially inflict brain damage resembling dementia.

Lead researcher Frederick Clasen admitted the full mechanism remains unclear at this stage. 'We don't know yet if the bacteria are causing the cognitive decline, or whether changes in the body due to Parkinson's allow these bacteria to grow,' he stated. However, his team believes they play an active role in worsening symptoms. Dr Lindsey Edwards, a microbiome scientist at King's College London, added that the oral microbiome could prove just as important as the gut microbiome. She noted that health issues often stem when 'bad' bacteria from the mouth travel down to the gut where they do not belong. If these bugs survive the stomach's acidic environment, they colonize the intestines, upsetting the microbial balance and triggering a damaging immune response. Worse still, if harmful mouth bacteria enter the bloodstream through bleeding gums, they can reach the heart and attack the lining of its four chambers, leading to infective endocarditis, a potentially fatal condition.

Could transplanting 'healthy' saliva shield people from such diseases? Several trials are currently investigating this possibility. One project at the University of Washington in the US examines whether it can cure halitosis, bad breath that affects one in four Britons. This issue usually arises when 'bad' bacteria break down food particles, creating foul odours. The procedure involves taking a swab from a donor's mouth, extracting micro-organisms, and mixing them with saline solution. Recipients then use this mixture as a mouthwash or receive a more concentrated version injected directly into the gums. The theory is simple: donated bugs crowd out the 'bad' bacteria responsible for bad breath. Four patients have received saliva transplants so far, with full trial results expected later this year.

Another team at Adelaide University in Australia is testing if transplants can stop tooth decay. Lab tests identified 250 types of 'good' bacteria in the mouth that, when transplanted, help prevent cavities by outnumbering the 'harmful' bacteria that erode tooth enamel. It is early days for this work, yet Dr Edwards remains convinced the oral microbiome's medical role will only expand. 'As more research is conducted, it'll be equally crucial [as our gut microbiome] to our health,' she says.

Practical steps exist to protect the 'good' bacteria in your mouth. Avoid alcohol-based mouthwashes. Regular use kills off beneficial microbes like actinobacteria, which are essential for regulating blood pressure, while allowing dangerous strains such as Fusobacterium nucleatum and Streptococcus anginosus to thrive. These harmful bugs link to gum disease and bowel cancer, according to the Journal of Medical Microbiology in 2024. Floss daily instead. This action shifts sticky plaque from between teeth where 'harmful' bacteria build thick layers.

Dr Lindsey Edwards from King's College London calls daily brushing and flossing among the finest habits one can adopt. She is a microbiome scientist who knows what works. Staying hydrated matters too. Sipping water washes away food bits and sugars that cling to teeth, giving harmful bacteria a feast.

Eat spinach instead. Leafy greens pack nitrates, plant compounds functioning as prebiotics. These feed the good bugs living in your mouth. Cutting back on alcohol is another smart move. Research indicates even two drinks daily throw off bacterial balance. Toxins from that liquid wipe out beneficial bugs before you know it.