How Does Diet Impact Brain Health? We Asked A Nutritionist

From upping your intake of fermented foods to limiting screen time before bed, here’s how to boost your brain health, according to a nutritionist

These Are The Key Pillars Of Good Brain Health

As you sit and read these words, your body is quietly at work: your breath is steady, your heart beats at a healthy rhythm, your temperature holds at 37°C and you have thoughts of the day rattling around your subconscious. All of this is controlled by the dense collection of wiring between your ears. As the seat of our personality, the home of our hopes and fears and the keeper of cherished memories, we should all pay a little more attention to the health of our brains. 

Recently, I find myself thinking about brain health more than usual. My colleague Professor Tim Spector visited Dr Sabine Donnai – founder of Viavi, a longevity clinic in Marylebone – to take the Cortex 360 cognitive health evaluation. Despite being one of the healthiest 67 year olds I know, his scan showed signs of inflammation and a buildup of environmental toxins.

You don’t need access to high-tech scans to start caring for your brain. Many evidence-based lifestyle changes can significantly support brain function as we age. Diet is one of the most powerful tools; according to the 2024 Lancet Commission report, around 45 percent of dementia cases could be prevented by addressing 14 lifestyle factors, several of which relate to nutrition and weight.

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The Gut-Brain Connection

Our organs don’t operate in isolation and nutrients from our food reach every part of the body, including the brain. One important connection is the gut-brain axis, a communication pathway that explains why we feel nauseous when anxious or get irritable when hungry. Central to this axis is the gut microbiome and the trillions of microbes that train our immune system.

Why is this important? Because inflammation, while essential for defending the body against injury or infection, can become harmful if it persists. Chronic low-grade inflammation affects the brain’s delicate structure and is linked to dementia and mental health disorders. Our lifestyle – especially diet – can help reduce excess inflammation.

Eating triggers an inflammatory response, but the type of food matters. Diets rich in plants and fermented foods have been shown to reduce inflammation by promoting a healthier gut microbiome. Adding foods like natural Greek yoghurt, kimchi or sauerkraut (with live cultures) can help. Avoid pasteurised or long-shelf-life versions, which often lack active microbes.

Omega-3 fats are also vital for keeping your brain and nerves in good health. Aim for a couple of servings of oily fish like salmon or mackerel each week. If you’re plant-based, include flaxseeds, seaweed or supplements. The typical western diet – low intakes of plants but high in refined carbs, unhealthy fats and ultra-processed foods – fuels inflammation, so swap in whole grains and ditch white bread and processed meats.

Sleep

Diet is just one piece of the puzzle – sleep also plays a critical role. Research shows poor sleep increases inflammation and risk of infection. During sleep, your brain takes the opportunity to clean up – the glymphatic system comes alive, draining metabolic rubbish from between cells that’s built up over the day. Most adults need seven to nine hours of quality sleep. We know what to do to support this: avoid screens in the bedroom, keep your sleep environment dark and cool and aim for consistent sleep-wake times.

(c) Emma Simpson, Unsplash

Exercise

Physical activity is another cornerstone of brain health. Regular exercise boosts brain blood flow, reduces inflammation and lowers the risk of vascular conditions that can impair cognitive function. It’s worth noting environmental factors, too. Professor Spector’s scan showed heavy metals and microplastics, likely from years of cycling in London. While we can’t eliminate pollution entirely, wearing an antipollution mask in busy cities may help reduce exposure. If these tips sound familiar, it’s because everything is connected. Your brain is your body – so what’s good for the whole, is good for the part.

Viavi, 9 Devonshire Place, London W1, viavi.com