Can diet improve your IQ?

What does your brain feed on?

Your brain is one of the most energy-hungry organs in the body, consuming around 20% of your daily calories. Just like a high-performance machine, it requires specific nutrients to fuel thinking, memory and problem solving.

Your brain primarily runs on glucose, which it gets from complex carbohydrates found in things like wholegrains, fruit and vegetables which provide a steady release of energy. It also relies heavily on healthy fats. Omega-3s, specifically DHA (docosahexaenoic acid) are critical for brain health. “DHA makes up about 30% of the brain’s fatty acids and is essential for the formation of new brain cells and communication between them,” explains registered nutritionist Rebecca Taylor.

“B vitamins are essential for the production of neurotransmitters, chemicals that transmit signals to the brain,” she adds. “Vitamin B6 is also involved in the production of your ‘happy hormones’ serotonin and dopamine, while B12 is crucial for the formation of something called myelin which helps nerve cells communicate efficiently.”

Iron is another essential nutrient to help brain health as its essential in delivering oxygen to brain cells, which is crucial for cognitive function and energy levels. Rebecca also stresses the importance of correct iron intake in young children as it may “impair brain development, leading to poor concentration and learning difficulties”.

Antioxidants are also key to brain health – things like vitamin E, flavonoids and polyphenols that help protect your brain from oxidative stress, which is linked to cognitive ageing.

The 5 best brain foods

There are so many great, healthy foods that can support good brain function. Rebecca recommends starting with her five favourites:

Fatty fish

Oily fish like salmon, mackerel and sardines are rich in omega-3 fatty acids, which support brain cell structure and neural communication, and may reduce neurodegenerative disease risks.

Berries

Berries, particularly blueberries, are packed with antioxidants and flavonoids that combat oxidative stress and promote brain plasticity, enhancing memory and cognitive performance.

Nuts & seeds

Things like walnuts, almonds and flaxseed provide healthy fats, antioxidants and vitamin E, protecting brain cells and potentially slowing cognitive decline.

Leafy greens

Green veggies like spinach, kale and broccoli are rich in folate and vitamin K, which support cognitive function and mood regulation.

Wholegrains

Oats, brown rice and quinoa provide that study glucose supply to the brain, promoting sustained focus and concentration throughout the day.

This is also a good time to mention gut-healthy foods and the communication between our gut and our brain (known as the gut-brain axis). This connection is becoming increasingly important in research on brain health.

“The gut is home to trillions of bacteria that play a role in digesting food and producing various chemicals that affect brain function, including neurotransmitters like serotonin,” Rebecca says. “Around 90% of serotonin is produced in the gut, so maintaining a healthy microbiome is key for mood regulation and cognitive health.”

That’s why a diet rich in prebiotics (wholegrains, fruits and vegetables) and probiotics (yogurt, kefir and kimchi) may in turn enhance brain function and protect against cognitive decline.

Eating regular meals throughout the day also ensures a steady supply of energy to the brain. That's why skipping meals or having irregular eating patterns can lead to blood sugar fluctuations which may impair concentration and cognitive function.

Rebecca recommends small balanced snacks containing protein, healthy fats and fibre between meals that may help sustain energy levels and cognitive performance.

These foods can muddle your thinking

Just as some food sharpen your mind, regular consumption of certain foods can dull it. Diets high in processed foods, sugars and unhealthy fats can impair cognitive function, and even increase the risk of neurodegenerative diseases.

“There is strong evidence that poor diet can contribute to cognitive decline later in life,” says Rebecca. “Diets high in saturated fats, refined sugars and processed foods are linked to an increased risk of developing cognitive disorders such as dementia and Alzheimer's disease.

“These types of diets can promote inflammation, insulin resistance and oxidative stress – factors that contribute to brain ageing and cognitive decline.”

• Sugary drinks and snacks can cause blood sugar spikes and crashes which can lead to brain fog and difficulty focusing.
• Ultra-processed foods like fast food and certain packaged snacks that contain additives and preservatives can impair memory and cognition over time
• Trans fats found in fried foods, margarine and some baked goods may contribute to inflammation, and have been linked to cognitive decline
• Excessive alcohol consumption can interfere with neurotransmitters leading to impaired cognitive function and memory loss
• High-sodium foods can raise blood pressure and reduce blood flow to the brain

Other ways to get an IQ boost

While diet plays a crucial role in brain health, it's only one piece of the puzzle. Other lifestyle habits can significantly enhance cognitive function memory and problem solving skills.

Regular physical activity is a great place to start as it increases blood flow to the brain, delivering oxygen and essential nutrients that help neurons function optimally. Aerobic exercises like running and swimming promote the release of something called brain-derived neurotrophic factor (BDNF), a protein that enhances learning and memory. Strength training and yoga have also been linked to better cognitive function by reducing stress and improving focus. According to the NHS we should be aiming for at least 150 minutes of moderate exercise per week including a mixture of cardio and strength training.

Sleep is also essential for memory and problem solving as the brain processes and consolidates information during that downtime. Studies have found that chronic sleep deprivation is linked to slower reaction times and impaired decision making. If you can, try to limit screen time before bed and create a dark, quiet sleep environment that can help you get 7-9 hours of quality rest per night.

Unsurprisingly mental stimulation like puzzles, reading, learning a new skill or engaging in challenging cognitive activities can help form new neural connections, and keep the brain sharp while improving problem-solving abilities and long-term memory.

Stress management is important for a healthy brain long term. In fact, chronic stress has been shown to increase cortisol levels in the body which can shrink the hippocampus, the brain's memory centre over time. Try deep breathing exercises, mindfulness meditation and even spending time in nature to help regulate stress hormones and improve mental clarity.

And finally, the best tip of all, and a great reason to spend more time with friends, is that social connection has been linked to strengthening cognitive resilience. Engaging in meaningful social interactions activates brain regions associated with thinking, problem solving and emotional regulation. Studies have shown that people with strong social networks have a lower risk of cognitive decline as they age, especially if these social interactions involve conversations, debate and group activities that can challenge the brain to process information quickly and critically.

So while your diet can't actually make you smarter it does have a direct impact on brain performance, while eating too much of the wrong foods may significantly reduce focus, memory and learning ability. Instead, prioritising a nutrient-rich diet can significantly improve your brain function and cognitive resilience over time, paired with other brain boosting habits.

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