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“Eat walnuts – they look like little brains!” It’s the sort of nutrition advice you’ll find floating around the internet, nestled somewhere between kale smoothies and promises that blueberries will make you a genius. But is there really such a thing as “brain food”? Can a snack boost your memory or stop dementia in its tracks?
The short answer: not exactly. The long answer: what’s good for your heart is also good for your brain. While no single superfood will guarantee your brain health, what you eat, alongside sleep, exercise, and social connection, does play a major role in long-term brain health.
Let’s bust a few myths and see what the science really says about feeding your brain.
Myth 1: “Superfoods” make your brain smarter
Blueberries, walnuts, turmeric or ginkgo … social media is awash with lists of brain superfoods that it’s claimed will prevent cognitive decline and boost IQ. If only it were that easy. Dementia touches two out of three New Zealanders either directly or through family, so it’s no surprise people go hunting for dietary silver bullets to boost their brain.
But large studies don’t point to one superfood; instead, they highlight whole eating patterns as the key to cognitive function. The Mediterranean and DASH diets, which are both rich in fruits, vegetables, wholegrains, nuts, legumes, olive oil and fish, have repeatedly been linked with slower cognitive decline, and people who adhered to a hybrid of the two, known as the MIND diet, were found to have the cognitive function of someone seven years younger.
So, although blueberries, walnuts and leafy greens are great, they work best as part of a balanced, healthy diet rather than being miracle workers on their own.
Myth 2: “Detox” or cleansing diets improve brain health
The idea that detoxing the liver or kidneys can magically boost brain function is a popular one, but the truth is that our bodies are already well-equipped to handle these tasks naturally. The real key to keeping your brain supplied with nutrients and efficiently clearing waste isn’t through fad detoxes but rather by maintaining a healthy cardiovascular system. After all, the brain and heart are quite literally connected by the arteries.
Your brain is a high-energy organ, relying on a constant supply of oxygen and glucose carried by blood. Anything that damages the cardiovascular system, such as high blood pressure, blocked arteries, excess cholesterol or insulin resistance, also puts your brain at risk. Plus, good blood flow to the brain also supports its waste-clearance system, thus helping to keep brain cells healthy and functioning well. So, maintaining a healthy cardiovascular system is key to ensuring the brain is supplied with the nutrients it needs and the brain’s waste-clearance system can work optimally. That’s undoubtedly why a Mediterranean-style diet supplemented with olive oil or nuts was found to improve cognition over four years in at-risk adults, while a low-fat diet was linked to decline. In other words, protecting your arteries helps protect your neurons.
Myth 3: A fatty diet is bad for your brain
Not all fats are created equal when it comes to your brain. While too much saturated fat can clog blood vessels and slow nutrient delivery, healthy fats, especially omega-3 fats like DHA found in oily fish, support brain function. Because about 60% of your brain is fat. DHA helps keep brain cell membranes flexible, supports signal transmission, and shields against oxidative stress.
Lower omega-3 levels have been observed in children with ADHD and older adults with cognitive decline, and have been linked to an increased risk of Alzheimer’s disease. But while a fish oil supplement might seem like a quick fix, most experts agree that food sources of healthy fats work best in the context of an overall healthy diet – think oily fish such as salmon, sardines and kahawai, along with other healthy fat sources such as avocado, nuts and seeds. The bottom line: fat isn’t your foe – your brain needs it to function. Just focus on the healthy kinds, especially omega-3s.
Myth 4: Specific “gut foods” are a shortcut to better thinking
Once upon a time, scientists thought your gut was just a food processor. Now we know it’s more like a bustling chemical factory with a direct line to your brain. Yes, the gut-brain connection is real, but thinking that a single food can “rewire” your mind is a stretch.
The “gut–brain axis” describes the constant conversation between the microbes in your gut and your nervous system, and diet has a key influence on that microbial community. A Western-style diet that is high in sugar, saturated fat, and ultra-processed foods is known to reduce microbial diversity, wipe out helpful species and encourage inflammatory microbes. That microbial imbalance has been linked with poorer cognitive function and a greater risk of depression.
On the flip side, fibre from fruit, vegetables, legumes and wholegrains feeds beneficial microbes. In return, they produce short-chain fatty acids such as butyrate, which reduce inflammation, support gut barrier integrity, and may even influence mood and cognition, noted a 2021 special feature on brain health and diet in Nutrition Reviews.
Scientists are even using the term “psychobiotics” for foods or microbes that beneficially influence mood and mental health. Fermented foods such as yoghurt, kimchi, sauerkraut and kefir add beneficial microbes directly. And polyphenol-rich foods such as berries, nuts and seeds, olive oil, cocoa, coffee, and green tea appear to act like prebiotics, by feeding beneficial bacteria and helping them to proliferate in the gut.
Still, the fact that many different dietary patterns have been linked to improved mental wellbeing suggests that the specific foods in the diet are less important to mental health than the overall beneficial dietary pattern – which is high in plant foods and low in ultra-processed foods, noted a 2021 review in Advances in Nutrition.
Myth 5: Diet is the ‘key’ to optimal brain health
No matter how much salmon or broccoli you eat, diet isn’t the whole story. Cognitive resilience is built on many pillars: physical activity, good sleep, social engagement and ongoing learning, as well as what you eat.
Contrary to what Instagram wellness posts would have you believe, there’s no single snack or supplement that guarantees sharper thinking or a dementia-free future. But a diet that’s good for your heart also supports your brain – think colourful plants, fibre, healthy fats, wholegrains, legumes, and fish. Add regular movement, quality sleep, and meaningful connection with others, and you’ve got the best “brain food” recipe science can currently offer.
As well as Jennifer Bowden’s columns in the NZ Listener magazine,listener.co.nz subscribers can access her fortnightly myth-buster column which explores food and nutrition myths.
