"..the food and nutrients you eat, the stress you experience, environmental toxins, and having a gut full of harmful microbes all affect your immune system at the deepest cellular level." Dr Susan Blum author of The Immune System Recovery Plan.

Most of us know the foggy feeling that comes with being unwell - the heavy head, the difficulty concentrating, the words that seem to get stuck on the tip of your tongue. For many, that’s just part of a short-lived illness. But for some, viruses can have a longer-lasting impact on our brain and thinking.

In midlife, when we’re already balancing work, family and health changes, the thought of viruses affecting our brain can feel unsettling. However, there are steps we can take to support our immune system so it’s better able to fight off infections and protect our brain.

In this article, I’ll walk you through how viruses can affect the brain, what that looks like in terms of memory and clarity, and then share five evidence-based ways to strengthen your immune system.

How Viruses Affect The Brain

Not every virus directly reaches the brain, but even those that don’t can still affect how our brain works. Here are some of the main ways this happens:

• Direct invasion: Certain viruses are able to cross into the central nervous system, sometimes travelling along nerves like the ones linked to smell.

• Blood–brain barrier disruption: This barrier usually protects the brain from harmful substances in the blood. But during an infection, inflammation can make the barrier more permeable, letting inflammatory molecules seep in.

• Neuroinflammation: Our brain has its own immune cells, called microglia. When they’re triggered by infection or inflammation, they release chemicals called cytokines. Short-term, this is helpful - but prolonged activation can disrupt how brain cells communicate.

• Indirect effects: Even without entering the brain, viruses can affect it through high inflammation, changes in oxygen levels, blood clotting, or metabolic shifts.

Most people recover fully after an infection, but sometimes the brain’s recovery lags behind the body’s. That’s when post-viral cognitive symptoms, often called “brain fog”, can show up.

What This Looks Like In Everyday Life

When the brain is affected by a viral infection, it can show up in ways that feel frustrating and disruptive to daily life:

• Struggling to find words or feeling like your thoughts are slower.

• Forgetting conversations or misplacing items more often.

• Difficulty concentrating or juggling tasks that would usually feel easy.

• Mental fatigue, where even small tasks feel draining.

For most people, these changes improve over time. But they’re also a reminder of how closely connected our immune system and brain health really are.

5 Ways To Support Your Immune System

While no lifestyle habit can make you “virus-proof,” there’s a lot you can do to give your immune system the best chance of fighting infections effectively and reducing their impact on your brain. Here are five powerful strategies:

1. Prioritise sleep

When you’re short on sleep, your immune system takes a hit. Studies show that even one week of sleeping less than six hours a night can weaken immune response and even make vaccines less effective. On the other hand, consistent, restorative sleep boosts the production of protective immune cells and antibodies.

Practical steps:

• Aim for 7–9 hours most nights.

• Set a consistent bedtime and wake-up time.

• Create a 60 minute wind-down routine without screens.

Start today: Decide what time you need to wake up tomorrow and count back 8 hours. That’s your target bedtime tonight.

2. Eat To Support Immune Health

The food you eat directly feeds your immune system. Protein provides the building blocks for immune cells. Vitamin D supports your first line of defence against viruses. Zinc plays a role in stopping viral replication, while antioxidant-rich fruit and vegetables help control harmful inflammation.

A Mediterranean-style diet, that is rich in vegetables, fruit, legumes, fish, nuts and olive oil, is especially supportive for both immunity and brain health.

Practical steps:

• Include a source of protein at every meal.

• Add colourful fruit and vegetables to your plate daily.

• Consider supplementing with vitamin D3, especially in the darker months.

Start today: Add one extra serving of vegetables to your dinner tonight, or swap an afternoon biscuit for a small handful of nuts.

3. Move Your Body Regularly

Moderate, consistent exercise mobilises immune cells, reduces chronic inflammation, and improves circulation. It also protects against the metabolic changes that can make us more vulnerable to infections. Importantly, you don’t need to overdo it - the sweet spot is regular, moderate activity combined with some strength work.

Practical steps:

• Aim for 150 minutes of moderate exercise each week (like brisk walking or cycling).

• Add two strength sessions weekly - bodyweight exercises or light weights are enough.

• Break up long periods of sitting with movement.

Start today: Take a 20-minute brisk walk this afternoon, or do a quick set of squats and wall push-ups at home.

4. Manage Stress And Calm Anxiety

Chronic stress keeps cortisol levels high, which can disrupt immune function and increase inflammation. Simple daily practices to calm your nervous system can make your immune system more balanced and effective.

Practical steps:

• Try 5–15 minutes of mindfulness or breathing exercises each day.

• Build in small breaks to move, stretch, or step outside.

• Stay connected with people who lift you up.

Start today: Try soft belly breathing (inhale for 4, hold for 4, exhale for 4, hold for 4) for five minutes after you finish reading this article.

5. Nurture Your Gut Health

A large part of your immune system is housed in your gut. The trillions of microbes that live there help train immune cells, regulate inflammation, and even influence brain health through the gut–brain axis. A healthy, diverse gut microbiome means a stronger, more balanced immune response.

Practical steps:

• Eat a wide variety of plant foods each week (aim for 20–30 types of fruit, vegetables, legumes, whole grains, nuts and seeds).

• Include fermented foods like live yoghurt, kefir, sauerkraut, or kimchi for beneficial bacteria.

• Limit ultra-processed foods, which can harm gut bacteria diversity.

Start today: Add one extra plant food to your plate - even something simple like a handful of berries or a sprinkle of seeds.

Start Today With Small Steps

The link between viruses and brain health might sound daunting, but the steps to protect yourself don’t have to be complicated.

Tonight, prioritise sleep. This week, add more colour to your plate and take a brisk walk. Today, spend five minutes on mindful breathing. And next time you’re preparing a meal, add something gut-friendly - a spoonful of sauerkraut, a drizzle of olive oil, or a small portion of beans.

Small daily actions build a stronger immune system and a more resilient brain. You don’t need to do everything at once - just start with one step today. Your future brain will thank you.

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