The Oral Gut Microbiome Axis: How Mouth Bacteria Impact Digestion, Immunity and Ageing

The oral microbiome-the diverse microbial community living in your mouth-is more than just a dental concern. It plays a central role in your immune function, gut health, and even your biological ageing. At Phenome Longevity, we explore this connection through our Oral Microbiome Test, which reveals how your oral bacteria influence your health far beyond the mouth.

What Is the Oral–Gut Microbiome Axis?

Your mouth is home to one of the most complex microbial ecosystems in the body. Known as the oral microbiome, it contains hundreds of bacterial species that live on your tongue, teeth, gums, and saliva. While some are harmful, many are beneficial bacteria that protect against infection, support digestion, and regulate immune responses.

Recent research has confirmed that your oral microbiome is directly connected to your gut microbiome via the oral–gut axis. Every time you swallow, you transport millions of bacteria from your mouth to your digestive system. This constant microbial exchange has a major influence on gut microbial balance, inflammation levels, and overall wellbeing.

How Oral Health Affects Gut Health

The mouth is the first step in your gastrointestinal tract. A healthy oral microbiome helps populate the gut with beneficial bacteria. But if the oral ecosystem is disrupted by gum disease, poor hygiene, or processed diets, it may introduce harmful bacteria into the gut-leading to dysbiosis and inflammation.

Studies have shown that pathogens like Porphyromonas gingivalis and Fusobacterium nucleatum-commonly found in gum disease-can travel to the gut and trigger intestinal inflammation, increasing the risk of:

• Type 2 diabetes
• Cardiovascular disease
• Inflammatory bowel disease (IBD)
• Autoimmune dysfunction

The oral–gut axis is proof that oral health is not isolated, but a critical part of whole-body health management.

The Oral Microbiome and the Immune System

The oral cavity is one of the body’s first immune barriers. It detects and filters out pathogens while interacting closely with the immune system. A balanced oral microbiome helps regulate immune responses-activating protection when needed, and calming inflammation when it’s not.

When oral dysbiosis develops:

• Inflammation may affect gums and mucosal tissue
• Bacteria can enter the bloodstream through inflamed tissues
• Chronic low-grade systemic inflammation may develop
• This inflammation may impact the heart, brain, joints, and gut

By keeping your oral microbiome balanced, you’re protecting both local and systemic immune health.

Oral Microbiome and Ageing

Microbiome diversity is a growing marker of biological age. People with a healthy and diverse oral microbiome tend to show signs of slower ageing, while microbial imbalance is linked to:

• Oxidative stress
• Chronic inflammation
• Decline in organ function
• Accelerated biological ageing

As we age, changes such as reduced saliva, weakened teeth, and lower beneficial bacteria contribute to oral dysbiosis. This, in turn, affects gut health, immune resilience, and cognitive clarity.

Protecting your oral microbiome supports not just your mouth, but also your gut-brain axis, cardiovascular function, and metabolic ageing.

How to Support a Healthy Oral Microbiome

Here are science-backed ways to nourish your oral microbiome daily:

1. Brush and floss twice a day to remove plaque and reduce harmful bacteria.
2. Eat a fibre-rich, plant-based diet to feed beneficial microbes.
3. Consume polyphenol-rich foods like berries, green tea, and olive oil to reduce inflammation.
4. Stay hydrated to stimulate saliva production and support natural cleansing.
5. Limit sugar and acidic foods that encourage harmful bacterial growth.
6. Use mouthwash sparingly-antibacterial formulas may wipe out good bacteria too.
7. Visit your dentist regularly to detect signs of microbial imbalance early.

Why This Matters for Longevity

Your oral microbiome influences your entire body. It affects digestion, immunity, inflammation, and ageing. Imbalance in this microbial ecosystem can trigger a cascade of health issues far beyond the mouth.

At Phenome Longevity, our Oral Microbiome Test UK gives you a clear snapshot of your unique bacterial profile-highlighting imbalances and providing personalised insights to help you:

• Improve oral and gut health
• Strengthen your immune system
• Lower systemic inflammation
• Support graceful, healthy ageing

Test Your Oral Microbiome Today

Take control of your health at the microbial level.

Our at-home oral microbiome test reveals the hidden links between your mouth and your gut, helping you make targeted lifestyle changes for long-term wellness.

✅ Non-invasive saliva sample

✅ Lab-tested with personalised report

✅ Results within days

Because longevity begins with the mouth.