In a previous post, I explored the 14 modifiable risk factors for dementia identified by the Lancet Commission on Dementia Prevention, Intervention, and Care. These include lifestyle elements such as physical activity, smoking, social connection, and hearing loss, areas backed by robust evidence. While we cannot change our chronological age or the genes we inherit, emerging research shows that gene expression can be influenced by modifiable factors such as nutrition and lifestyle. This positions diet as a potentially important factor in maintaining cognitive function and supporting long-term brain health. As global interest in dementia prevention grows, so too does curiosity about the role of diet. This post builds on that foundation by taking a closer look at how nutrition influences cognitive health, and why it deserves greater attention in dementia prevention frameworks.

Nutrition can influence both day-to-day brain performance and long-term cognitive resilience. Given the limited success of drug treatments for Alzheimer’s disease, more attention is being given to dietary strategies that might help prevent or slow cognitive decline.

Emerging nutrients of interest include:

• B vitamins – important for homocysteine regulation and neurotransmitter synthesis (1)
• Vitamins D and E – for immune and antioxidant functions
• Omega-3 fatty acids, choline, and polyphenols – for inflammation and membrane integrity
• Gut health and the microbiome – due to its wide-reaching impact on the brain

These findings point towards a need for personalised, multi-nutrient approaches rather than generalised dietary advice.

Two of the most studied eating patterns in brain health are the Mediterranean and MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diets.

What the research shows:

• Both diets are rich in fibre, healthy fats (especially omega-3s), and antioxidant plant compounds.
• Long-term studies suggest they are linked to a lower risk of Alzheimer’s and slower memory decline (2).
• The MIND diet places added emphasis on leafy greens, berries, nuts, legumes, and fish, while limiting saturated fat and added sugars (3).

However, findings from clinical trials are mixed. Results suggest individual factors, such as genetics, gut health, and lifestyle, likely influence how effective these diets are for brain health.

Omega-3 fatty acids, especially DHA and EPA, play essential roles in brain development and inflammation control.

Key findings:

• Higher fish intake (salmon, sardines, mackerel) is linked with a lower risk of cognitive decline (4)(5).
• One study found that just one fish meal per week was associated with a 60% lower risk of Alzheimer’s (6).
• Higher blood levels of DHA are linked to better memory and larger brain volume.
• Supplements may benefit people with low omega-3 levels or mild cognitive impairment, though less so in later disease stages (7) (8) (9) (10).

Omega-3s are not a cure-all, but they are an evidence-based part of a brain-supportive diet.

These vitamins help regulate homocysteine, support neurotransmitter production, and contribute to brain metabolism.

What the research shows:

• Elevated homocysteine (a naturally occurring amino acid in the blood, regulated by B vitamins) is linked to cognitive decline and brain shrinkage (11) (12) (13).
• The VITACOG trial found B vitamins significantly slowed brain atrophy in people with mild cognitive impairment, especially when omega-3 levels were adequate (13)(14).
• B6 levels may be particularly important in predicting future cognitive risk (15).

These nutrients are most effective as part of a broader, tailored nutrition plan.

Polyphenols are found in berries, tea, cocoa, and spices like turmeric. They work alongside antioxidant vitamins like C and E.

How they help:

• Reduce brain inflammation and oxidative stress
• Support blood flow and brain plasticity

Research highlights:

• Regular intake of flavonoid-rich foods (berries, cocoa, tea) is linked to better memory and slower cognitive ageing.
• In the Nurses’ Health Study, berry intake delayed cognitive ageing by up to 2.5 years (16).
• Some studies show acute memory and focus improvements even within hours of consuming these foods (17)(18)(19)(20).

Whole foods tend to outperform single supplements, likely due to the synergistic effect of multiple compounds.

Choline supports memory, attention, and neuronal membrane integrity. It is a precursor to acetylcholine, a neurotransmitter critical for learning.

Evidence suggests:

• Higher choline intake is associated with better memory and reduced dementia risk.
• Phosphatidylcholine may reduce amyloid-beta buildup, a hallmark of Alzheimer’s.
• My own published review (PMID: 39357562) highlights the potential of choline-rich diets to support neuroplasticity (21).

Top food sources: eggs (yolk), liver, soy, salmon, broccoli, quinoa.

Choline-rich foods are a practical part of a brain-supportive diet, especially when consumed regularly.

Your gut and brain are in constant communication via the microbiome (trillions of microbes living in your gut), which can impact memory, mood, and cognitive function.

What we know:

• Gut bacteria produce short-chain fatty acids (SCFAs, anti-inflammatory compounds made when fibre is fermented), which may reduce brain inflammation and help support the blood-brain barrier (22).
• An imbalance in gut microbes, known as dysbiosis, has been linked to cognitive changes, anxiety, and depression (23).

Gut-supportive foods:

• Prebiotics: garlic, onions, leeks, oats, bananas
• Probiotics: yogurt with live cultures, kefir, sauerkraut, kimchi
• Fermented foods: miso, tempeh, kombucha (23).

A diverse, fibre-rich diet with fermented foods may help protect cognitive health as we age.

Vitamin D regulates inflammation and supports brain regions involved in memory.

Research shows:

• Low levels (<30 nmol/L) are associated with higher dementia risk and poorer memory (25)(26).
• Optimal levels (around 60–70 nmol/L) are linked to better cognitive function (27).
• Supplementation may benefit those with low baseline levels.

Food sources: oily fish, egg yolks, fortified cereals, milk, and plant milks. Sunlight also helps, but varies by season, geography, and skin tone.

Summary – How Do Nutrients Support Brain Function?

Here are the key ways nutrients influence brain health:

• Energy production: B vitamins help neurons meet high energy demands.
• Blood-brain barrier integrity: Omega-3s and other nutrients help maintain this protective shield.
• Inflammation control: Polyphenols and omega-3s may reduce chronic brain inflammation.
• Oxidative stress protection: Antioxidants like vitamins C and E may help neutralise damaging free radicals.
• Neurotransmitter synthesis: Nutrients like choline and B6 support communication between brain cells.
• Structural support: DHA and B vitamins help preserve brain structure and slow atrophy.

Conclusion

While nutrition is not a stand-alone solution for preventing or treating cognitive decline, the evidence linking diet and brain health continues to grow.

Personalised dietary interventions, including whole dietary patterns like the Mediterranean and MIND diets, and nutrients such as omega-3s, B vitamins, and choline, offer promising avenues for supporting cognitive function across the lifespan.

This remains an evolving area of science that deserves greater attention in both public health and clinical practice.

References

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