What your mouth is telling you: Saliva’s hidden clues to your health

When it comes to health warnings, most people look out for symptoms like chest pain, fatigue, or fever. But scientists are now pointing to something far more subtle and often overlooked: your saliva.

Long dismissed as "just spit or ni mate tu," saliva is increasingly being recognised as a silent health alarm, offering early clues to everything from dehydration and diabetes to respiratory infections and autoimmune disease, not just helping in digestion.

“Saliva plays a much bigger role than just keeping your mouth moist,” said a researcher at the Radboud University Medical Centre’s Amalia Children’s Hospital in the Netherlands.

“It helps us fight disease, digest food, and, increasingly, tells us what’s happening deeper inside the body.”

Saliva contains powerful biological information: enzymes, hormones, antibodies, and even traces of viruses and diseases. Changes in how much you produce, how it feels, or how it tastes can be a first sign that something is wrong, often before traditional symptoms emerge.

“Your mouth may be the first place your body tries to tell you something,” says Dr Aisha Noor, an oral health expert based in Nairobi.

“We just have to start listening.”

Saliva beats blood in new respiratory study

That listening is already paying off in medical research. A new study by Dutch researchers has found that saliva can be more effective than blood in detecting serious childhood illnesses.

In a joint study conducted by Radboudumc Amalia Children’s Hospital and UMC Utrecht Wilhelmina Children's Hospital, researchers tested saliva samples from 100 children with recurrent respiratory infections.

The findings, published in the European Respiratory Journal (August 2024), revealed that children with low levels of broadly protective antibodies in their saliva were significantly more likely to suffer frequent and severe episodes of pneumonia.

“We found no strong correlation between antibodies in the blood and the severity of illness,” said Dr Lilly Verhagen, pediatric infectious disease specialist at Radboudumc. “But saliva offered critical insight. It told us which children were more vulnerable.”

These antibodies, found in the airways but largely absent in the blood, provide broad protection against a wide range of respiratory pathogens.

Remarkably, researchers found that pre-pandemic saliva samples contained antibodies capable of recognising SARS-CoV-2.

Bacteria and the microbiome

Beyond antibodies, researchers also studied bacterial imbalances in the respiratory tract. One bacterium, Haemophilus influenzae, was found in higher levels in children who got sick more often during colder months.

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Though commonly present in the nose and throat, this bacterium worsens infections when it becomes dominant.

The takeaway was that saliva does not just reflect immune strength; it reveals patterns in respiratory health, potentially allowing doctors to intervene earlier and more precisely.

What else might your saliva be telling you

While the study focused on children, medical experts say saliva can reveal even more about adult health, too. Shifts in how much saliva you produce, whether too much or too little, can serve as a warning sign for deeper issues.

Too little saliva (dry mouth/xerostomia) may signal:

• Dehydration
• Poorly managed diabetes
• Autoimmune diseases like Sjogren’s syndrome, a chronic autoimmune disease in which the body’s immune system mistakenly attacks its moisture-producing glands, primarily the salivary and tear glands.
• Side effects from medications
• Chronic stress or anxiety

Too much saliva may point to:

• Gastroesophageal reflux (GERD)
• Parkinson’s disease or other neurological conditions
• Pregnancy-related hormonal shifts
• Oral inflammation or infection

“Dry mouth isn’t just uncomfortable, it increases your risk of tooth decay, gum disease, and even fungal infections,” warns Dr Noor.

Saliva testing: the future of non-invasive diagnosis

What makes saliva especially promising is how easy and pain-free it is to test, especially compared to blood draws.

Researchers are now exploring saliva’s potential in diagnosing:

• Viral infections like COVID-19 or HIV
• Hormonal imbalances
• Stress and cortisol levels
• Genetic mutations and early-stage cancers

For low-resource clinics and rural hospitals, saliva testing could offer an affordable and readily available alternative to lab-based blood testing,  especially for children.

“Saliva is like a medical dashboard hiding in plain sight,” says Dr Samuel Mburu, a biochemist at a local hospital in Ruiru.

“It has all this data. We just haven’t been using it to its full potential.”

Experts recommend being alert to the following changes in your saliva or mouth: Persistent dry mouth or bad breath, difficulty swallowing, sudden increase in drooling or saliva pooling, unusual or metallic taste and mouth ulcers or frequent infections.

If any of these persist, speak to a dentist or doctor. It might be your body’s first attempt to communicate a bigger problem.