Neurological conditions are now the leading cause of illness and disability worldwide, overtaking disease categories like cancer and heart disease. According to the World Health Organisation (WHO), they affect more than three billion people.
The state of our collective brain health has even been described as an ‘emergency’ by the Federation of European Neuroscience Societies. And it's easy to see why: declining neurological health on this level is a new threat on both a micro and macro level.
Poor brain and mental health is linked to lower lifetime earnings for individuals and the social care costs of dementia in the UK now outstrip those for cancer, stroke and heart disease combined.
This all means finding affordable and accessible ways to protect neurological wellbeing should be a public health priority. And growing research suggests that nutrition could be a valuable tool in such a crusade.
In one recent major study, researchers took data on food preferences from 181,990 participants from the UK Biobank, a database of de-identified health information. From 140 food and drink items, the research group divided the participants into four dietary subgroups: Starch-free or reduced starch, vegetarian, high protein and low fibre, and balanced.
This dietary data was then analysed against a range of physical markers and factors including mental health, cognitive functions, blood and metabolism biomarkers, and brain magnetic resonance imaging (MRI).
The researchers' conclusion to all this? The nutrients in your regular diet can determine brain structure, which influences mental health and cognition.
So, what should we be eating to keep our brains healthy? Here are three key science-backed tips.
1. Get the right micronutrients
Nutrients are essential for brain development. We see this most clearly in cases where individual nutrients have large effects on neuronal structure and cognition. For example, iodine deficiency is the leading cause of preventable brain damage worldwide and during pregnancy can lead to permanently suppressed offspring IQ (67 per cent of pregnant women are iodine deficient). The NHS advises adults to have 140 micrograms of iodine a day, with seaweed, dairy products and fish being rich sources.
Similarly, another B vitamin, cobalamin (B12) is so important for normal neurological function that deficiency causes a profusion of psychological and cognitive impairments including confusion, impaired judgement, anxiety, depression, forgetfulness and dementia.
B vitamins are known for keeping the nervous system healthy and allowing the body to break down and release energy from food. It's currently recommended by the NHS to have 1.5 micrograms a day of vitamin B12, with the nutrient found in meat, fish, eggs and cheese. Vegetarians often take a supplement, commonly found in tablet form.
Polyphenols (found in berries, tea, coffee and legumes) and omega-3 fats (from oily fish) help neurogenesis, which promotes the growth of new connections in the adult brain and protects ageing brain cells.
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2. Increase your fibre intake
Low fibre intake contributes to pro-inflammatory changes in the gut microbiome and the degrading of the protective layer of mucus that lines the gut, as fibre-starved microbes go in search of something else to eat.
These incursions on gut barrier integrity can allow gut bacteria into the bloodstream, where they are identified by the immune system as pathogens, triggering an inflammatory response. This peripheral inflammation can then provoke neuroinflammation, which is a recognised feature of major depression, schizophrenia, OCD and Alzheimer’s disease.
Our diets via our microbiota can also protect our brains. When gut microbes break down fibre they produce a range of by-products including vitamins and neurotransmitters. One class of by-products are short chain fatty acids (SCFA), which not only feed the cells that line the gut, helping to support the integrity of the gut barrier, but can do the same for the blood-brain barrier (BBB) too.
The BBB is very important. It's a highly selective structure that prevents toxic proteins and other pathogens from entering the brain where they could trigger inflammation or other dysfunction. We know that impaired BBB integrity is an early precursor to neurodegenerative conditions like Alzheimer’s disease, raising the possibility that diets low in fibre could be contributing to neurological illness.
Worryingly, the biobank study found that people with low-fibre diets had a lower volume of tissue in 11 regions of the brain, compared to those with a balanced diet. That's significant as higher overall brain volumes are associated with protection against neurodegenerative illnesses (called cognitive reserve).
Currently, not a single age group in the UK is meeting the recommendations for fibre intake, which is 30g for most adults. Oats, legumes (such as beans and lentils), fruit and vegetables are all great sources of fibre.
3. Avoid fad diets
Another concern is the online promotion of extreme dietary practices like the carnivore diet, which encourages people to eat only animal products (meat, eggs and dairy) and to completely exclude fibre-rich plant foods.
Such diets are endorsed as a fast track to fat loss and muscle growth and have, consequently, become popular with young men. But, while on the plus side, they might encourage young people to eat fewer ultra-processed foods, they could be introducing immunological changes that put young brains at increased risk at what is already a vulnerable time for mental health.
What is clear is that, as a nation, we are not eating the foods known to support brain health and development. Twenty years after the campaign was introduced, 67 per cent of us are not hitting our 5-a-day.
Close to 60 per cent of our diets are ultra-processed, and there is an inverse relationship between the proportion of ultra-processed foods in the diet and nutrient status. These stats alone should give us pause. The brain is an extraordinarily hard-working organ with a consistently high demand for energy and a broad range of nutrients – nutrients that most of us aren’t getting enough of.
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