The easy tweaks that may make your mind EIGHTEEN years youthful: What to eat, what dietary supplements to take… and the one meals that is a killer to your gray matter, revealed by a world-leading neuroscientist

Yesterday, in the first part of this exclusive series, world-leading neurologist Dr Majid Fotuhi explained how by using proven techniques and regular physical exercise it’s possible to substantially improve your memory, sharpen your thinking skills and even help keep dementia at bay.

Today, in the second part of this unmissable series from his new book, The Invincible Brain, we’ll see how making changes to our daily food choices and sleeping habits can also pay big dividends for our memory and cognitive function.

We know the food choices we make every day can have a big impact on our bodies – but how often do you stop to think about the impact on your brain?

While some foods can be medicinal – helping to resolve or reduce weight issues or inflammation, for instance – others can be harmful, causing or contributing to these same problems and ultimately to brain shrinkage.

That’s because the brain is intimately connected to every other organ and tissue in our bodies, as we saw yesterday in the first part of this exclusive series on how to make your brain sharper in just 12 weeks.

Everyday lifestyle habits can play a big role in how well our brains function now, as well as how gracefully they age and our risk of developing conditions such as Alzheimer’s.

This is why, as a leading neurologist and a professor at Johns Hopkins University’s Mind/Brain Institute, I’ve developed the Brain Fitness Programme, based on the latest science, to help you make your brain smarter today as well as keeping dementia at bay.

Rooted in decades of clinical experience, this 12-week programme also forms the basis of my new book, The Invincible Brain.

Today, I’ll explain the best foods to eat and the practical steps you can take to ensure you get a refreshing night’s sleep – both are crucial to building a bigger, quicker and happier brain.

One special connection between brain and body is the gut-brain axis: the source of a continual conversation about food and digestion.

The gut has its own nervous system – the enteric nervous system – which means there are neurons in your digestive tract that operate independently from those in your brain, although the two systems are in constant communication via a major nerve highway called the vagus nerve.

This means that stress and emotions in your brain can affect how well your digestive system works and which types of microbes thrive there. Meanwhile, digestive problems can affect the brain, too, causing brain fog, mood swings and fatigue.

Nourishing the ‘good’ bacteria in your gut microbiome – for instance with a high-fibre diet – can improve mood.

One review of studies examining the relationship between depression and the consumption of fibre (found in legumes and whole grains) found those who ate the most fibre in their diets were less likely to get depression.

Although a high-fibre diet may not fully resolve depressive symptoms, it can help reduce their severity.

But the gut is also home to unfriendly ‘bad’ bacteria, which feed on sugars and saturated fats, and cause inflammation and weaken the gut lining.

Over time, this can lead to ‘leaky gut’, whereby toxins seep through the weakened lining, into the blood stream and from there into the brain’s blood vessels, causing ‘leaky’ brain. This is associated with brain inflammation, higher amyloid levels and a greater risk of Alzheimer’s.

One special connection between brain and body is the gut-brain axis, reveals our writer

Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP.

Why what you weigh matters

Many things – from genetics to eating too much junk food – can contribute to obesity, but the bottom line is that having a BMI of 30 or above is associated with atrophy in the hippocampus.

The higher the BMI, the smaller the hippocampus (involved in memory), regardless of whether you also have diabetes, according to one study. 

Another study, involving 473 men and women aged between 20 and 87, found that in those aged over 40, being overweight or obese was associated with a brain that appeared up to ten years older than a lean person’s of the same age.

As a leading neurologist and professor at the Mind/Brain Institute at Johns Hopkins University, I have developed a science-based 12-week programme to help you improve your memory

People with obesity also have much higher rates of other conditions that can harm brain health – including sleep apnoea, lower blood flow to the brain, raised cortisol levels and inflammation in the brain, regardless of whether they also have diabetes.

Studies also suggest that those with higher HbA1c levels (a measure of blood sugar over time, used to diagnose diabetes and often associated with obesity) were likelier to have more brain shrinkage.

A report I co-authored in 2013 found that obesity is linked to a 2.4 per cent decrease in brain volume, especially in the hippocampus and frontal lobes (involved in impulse control and decision-making).

Reward pathways in people with obesity are also more active in response to sugar consumption and light up much more on PET scans. This negative neuroplasticity explains why people who cross the line to obesity find it so much harder to lose weight.

Drugs such as Ozempic and Mounjaro (GLP-1 agonists) appear to have many benefits for lowering blood sugar levels, reducing weight and significantly reducing inflammation. They have also shown some promising results in helping to prevent Alzheimer’s in people with diabetes.

They may provide a helpful kickstart for people with obesity who have previously been unsuccessful with diet and exercise alone.

Long-term, however, the best strategy for both general and brain health is to focus on eating a diet rich in Mediterranean foods.

Eat your way to an invincible brain 

Numerous studies show that those who eat a primarily Mediterranean diet have slower cognitive decline, a lower risk of mild cognitive impairment progressing to Alzheimer’s and a reduced risk of the disease itself.

In one 2023 study, researchers found that the brains of people who most strictly adhered to a Mediterranean diet had quantities of amyloid and tau similar to being 18 years younger than people who adopted the most relaxed attitude to the regimen.

The Mediterranean diet is generally high in vegetables and fruit, seafood, whole grains, olive oil, along with strong social support and an active outdoor lifestyle.

But there’s no one specific diet, so I have divided some of the key ingredients into three categories to help you decide which changes you’d like to prioritise. 

You’ll notice that some foods crop up in more than one category. I’d suggest using this to make a list of foods you’d like to include and eliminate.

Keep a record of your progress (you can use the charts from my book or in my app), scoring yourself between 0 and ten depending on how well you meet your goals.

Foods to boost blood flow to your head 

Poor circulation to the brain contributes to cognitive impairment, stroke risk and brain shrinkage. Neuropathological studies show that 90 per cent of older adults diagnosed with Alzheimer’s also have vascular abnormalities in their brains, underlining the close connection between heart and brain health.  These Mediterranean staples naturally enhance both:

• Beetroot: This root vegetable is rich in nitrates, which stimulate nitric oxide production and dilate blood vessels. Older adults who consumed beetroot juice were found to have better circulation in areas of the brain associated with thinking and decision-making, according to one study. Research shows diets high in nitrates can increase blood flow to the brain.
• Leafy greens: These are also rich in nitrates and contain folate and magnesium, which support healthy brain blood flow.
• Citrus fruits: Includes oranges, lemons and grapefruit, which contain flavonoids that improve circulation and reduce stroke risk. Rich in vitamin C. 
• Walnuts: They contain L-arginine, a compound that enhances nitric oxide production, promoting the dilation of blood vessels in both heart and brain. 
• Olive oil: Reduces arterial stiffness, supporting vascular and long-term brain health. In fact, a recent study found that extra virgin olive oil strengthens blood-brain barrier function in people with mild cognitive impairment, helping to keep out substances that might accelerate cognitive decline. 
• Pomegranates: This fruit increases nitric oxide levels, improving oxygen flow to brain cells. 
• Dark chocolate (70+ per cent cocoa): Contains flavonoids that increase nitric oxide production, enhancing blood circulation in brain and body. 

Foods to boost ‘brain fertilising’ compounds 

The following foods help stimulate the production of BDNF, the ‘brain fertilising’ protein that helps create new neurons and brain connections.

• Fatty fish: The DHA (docosahexaenoic acid) in fatty fish, such as salmon, herring and sardines, specifically promotes BDNF release, encouraging the growth of new brain cells and increased synapses.
• Eggs: Egg yolks are rich in choline, essential for producing acetylcholine, a neurotransmitter crucial to memory and synaptic function. Research shows choline can help to improve verbal memory in older adults and may help prevent Alzheimer’s.
• Dark chocolate (70+ per cent cocoa): Cocoa flavonoids boost BDNF production and improve brain connectivity, with studies showing they also enhance cognitive function.
• Berries: Fruit, such as blueberries, are high in BDNF-boosting polyphenols.
• Legumes: Plants in the pea family – such as lentils, chickpeas and peas – contain zinc and magnesium, which enhance BDNF activity. They’re also an excellent source of filling fibre, important for maintaining a healthy microbiome and helpful for weight management. 

Foods to reduce inflammation 

The following ingredients contain powerful polyphenols and other antioxidants – including omega-3 fatty acids – that benefit brain health by combatting inflammation, which contributes to cognitive decline, dementia and Alzheimer’s.

• Fatty fish: Salmon, sardines and tuna are high in omega-3s, which help lower inflammatory markers in the brain. A study I carried out in 2009 found that individuals with higher blood levels of omega-3s were less likely to develop Alzheimer’s. Brain benefits start at around 28g a day and increase with consumption, according to a 2024 study on fish consumption, cognitive impairment and dementia.
• Olive oil: One study that followed 92,000 people for more than 28 years found those who consumed more than 7g a day (about 1 ½ teaspoons) had a 28 per cent lower risk of dementia-related death than those who rarely ate it. Olive oil can also help with pain relief. Extra-virgin olive oil contains oleocanthal, a natural anti-inflammatory compound similar to ibuprofen.
• Turmeric: This spice contains curcumin, a potent active compound that crosses the blood-brain barrier and helps reduce brain inflammation. Its numerous antioxidant properties offer protection against joint pain, heart disease and even cancer. For the brain, it reduces oxidative stress, activates BDNF (protein that helps trigger the growth of new brain cells) and boosts feel-good chemicals such as dopamine, making it one of the most powerful spices for brain protection.
•  Berries: Blueberries, raspberries and strawberries, are high in flavonoids and anthocyanins, which reduce oxidative stress and inflammation, including in the digestive tract and brain. They’re low in sugar compared with many other fruits.
•  Leafy greens: Spinach, kale, Swiss chard and rocket, are rich in antioxidants, fibre and polyphenols that help protect neurons from damage. The 2023 Mediterranean diet study mentioned above found that those who ate the most leafy greens had the lowest amyloid levels of all.
•  Nuts and seeds: Walnuts, almonds and chia seeds, for example, are packed with polyphenols, vitamin E, fibre and B vitamins, reducing inflammation and benefitting cognitive function.

Why sugar is so bad for grey matter

High blood sugar levels cause brain inflammation, which can result in brain shrinkage

If you could only make one dietary change, eliminating added refined sugar would be top of the list.

As well as table sugar, this comes in various guises including cane sugar, beet sugar and high-fructose corn syrup and is found in highly processed foods, breakfast cereal, cakes and pastries.

Eating too much refined added sugar drives blood sugar levels too high, leading over time to obesity, type 2 diabetes and to damage to eyesight, nerves, the heart, kidneys and brain.

High blood sugar levels also cause brain inflammation, which can result in brain shrinkage, as well as damaging the small blood vessels in the brain, restricting blood flow and increasing the risk of stroke and vascular dementia (where inadequate blood flow means brain cells are damaged and eventually die off).

Some researchers even call Alzheimer’s disease ‘type 3 diabetes’, because insulin resistance – caused by excessive sugar – can impair the brain’s ability to clear toxic amyloid plaques.

But sugar is hard to quit. Refined sugar is significantly sweeter than anything found in nature, which desensitises your taste buds over time. Very sugary treats such as sweets and biscuits trigger a dopamine response in the brain very similar to what we see in someone who uses tobacco, alcohol or cocaine – so the more you consume, the more you crave.

Consuming too much refined sugar leads to a rapid spike in blood glucose levels. To rebalance, the body hurriedly releases a large amount of insulin – but sugar levels may drop too low, leaving you feeling hungry again. Welcome to the blood-sugar rollercoaster.

Sugar can also affect mood, stress levels and emotions. A review of more than 300 previous studies examining sugar consumption, anxiety and emotions found ‘overwhelming evidence’ that sugar consumption results in physical brain changes, altered emotional processing and modified behaviour in both rodents and humans.

What to do if test shows that you have the ‘Alzheimer gene’

Many people worry that they will go on to develop Alzheimer’s disease if they have the ApoE4 genetic variant linked with a higher risk of the disease.

Indeed, with the growing popularity of genetic testing, these days I often see patients who have discovered they have the ApoE4 variant and have become unnecessarily preoccupied – sometimes obsessed – with the constant gnawing worry that they’ll develop Alzheimer’s.

Yet they may not appreciate that obesity, diabetes, insomnia, sleep apnoea and many other issues all increase the risk of developing Alzheimer’s as much – if not more – than having a copy of ApoE4.

In fact, having all these risk factors together can increase the risk of Alzheimer’s 16-fold, which is a much higher contribution that having one gene variation in ApoE.

We all have two copies of the ApoE gene – one inherited from each parent. But there are variants – and of these ApoE4 is associated with a higher risk of developing Alzheimer’s and/or developing it at a younger age, for instance in your 60s or 70s.

But even if you do have one or two copies of ApoE4, it’s by no means inevitable you’ll go on to develop the disease.

More reassuringly, there’s good evidence that adopting a healthier lifestyle can substantially reduce your risk.

One powerful tool is regular physical exercise, as I explained in yesterday’s Daily Mail. Essentially, exercise appears to inhibit amyloid accumulation, linked to Alzheimer’s, as research has shown.

A recent study examined the amyloid levels of 204 adults with an average age of 74 – of whom a quarter had the ApoE4 variant. Researchers discovered that the ApoE4 carriers who were highly physically active had the same low-level of amyloid in the brains as people who didn’t have the variant.

Isn’t it exciting knowing that you can virtually eliminate an elevated disease risk just by doing something as simple as exercise?

If you are new to physical activity, this knowledge might provide the motivation you need to take charge of your health and brain ageing.

These brain boosting benefits were illustrated by a patient of mine, a successful lawyer in her 50s, who came to me anxious and scared after discovering she had the ApoE4 variant.

I reassured her that the variant was not a definitive indicator that she’d get Alzheimer’s and she undertook my 12-week programme.

By the end, her memory scores had improved immeasurably – from the 40th percentile to the 55th percentile – and she was delighted.

As part of the programme, she’d learned to organise her busy work and family life more effectively, reduce her stress levels and make more time for exercise and brain training.

She also learned tricks for improving her memory – and could now memorise a list of 100 words.

Excited by her excellent progress, she determined to continue improving her memory after the 12-week programme was complete.

With her new lifestyle habits, and attitude, when she came to repeat her memory tests with us again a year later, her memory score had increased to the 70th percentile.