The oral-gut-brain axis: New research on mouth, microbiome and memory

The connection between the oral and gut microbiomes and brain health

In another article, we explored the fascinating area of research revealing how the microbes in our mouths and guts can influence our brains, moods and the risk of conditions like Alzheimer’s disease. This article highlights the most recent findings of this hugely important pathway: the oral-gut-brain axis and why you, and your brain, should care.

What is the oral-gut-brain axis?

The oral-gut-brain axis refers to the complex communication network between the mouth, the digestive tract and the brain. Research shows that the oral microbiome – the community of bacteria in the mouth – plays a crucial role in shaping gut microbial diversity and influencing cognitive health.

In other words, it’s not just “what you eat”, it’s also “what your microbes metabolise and message”.

Latest research on the oral-gut-brain connection

🔬 In a 2025 study, exploring how oral microbes can modulate gut microbiota and influence brain function, researchers found that imbalances in oral bacteria – often driven by poor oral hygiene, diet and/or inflammation – could lead to downstream gut dysbiosis, immune activation and neuroinflammation. This, in turn, may contribute to cognitive decline and neurodegenerative changes.[1]

🧠 Another 2025 study showed that microbial diversity and fitness in both the gut and oral microbiomes are linked to Alzheimer’s risk. Reduced diversity was associated with increased inflammation and disrupted gut-brain communication, especially during critical windows of cognitive development and ageing.[2]

🥗 A third 2025 study examined how the Mediterranean diet supports a healthier oral-gut-brain axis. Rich in polyphenols, prebiotic fibres and omega-3s, this way of eating was shown to nurture beneficial bacteria that produce anti-inflammatory compounds, helping to reduce amyloid plaque formation and protect brain function.[3]

Why microbiome matters for memory

These findings suggest that supporting your oral and gut microbiome may be just as important for your mind as it is for your digestion. Chronic gum disease, constipation, poor diet or excessive sugar intake may all disrupt this axis and compromise brain health over time.

This evidence highlights the therapeutic potential of prebiotics, probiotics, compounds like omega-3 fatty acids and polyphenols, dietary interventions and intermittent fasting in restoring microbial balance, reducing inflammation and minimising neurodegenerative risks.[1-3]

Tips to support your oral-gut-brain axis

🪥 Brush and floss daily

🥦 Eat a diverse, fibre-rich diet with plenty of prebiotics (onions, garlic, leeks)

🥜 Include healthy fats and plant polyphenols (olive oil, nuts, herbs, berries)

🧘‍♀️ Minimise chronic stress – it alters gut motility and microbial balance

🚶 Move daily – physical activity enhances gut-brain communication

Brain health starts well before symptoms appear – and often well below the neck.

References:

[1] Adil NA, et al. The oral-gut microbiome-brain axis in cognition. Microorganisms 2025;13(4):814, https://pubmed.ncbi.nlm.nih.gov/40284650/

[2] Jamerlan AM, et al. Microbial diversity and fitness in the gut-brain axis: influences on developmental risk for Alzheimer's disease. Gut Microbes 2025;17(1):2486518, https://pubmed.ncbi.nlm.nih.gov/40207973/

[3] Mafe AN, Büsselberg D. Could a Mediterranean diet modulate Alzheimer's disease progression? The role of gut microbiota and metabolite signatures in neurodegeneration. Foods 2025;14(9):1559, https://pubmed.ncbi.nlm.nih.gov/40361641/