Alzheimer’s disease is largely a preventable disease, and we know quite a lot about what people need to do to help prevent it. So says Professor David Smith, former Deputy Head of the Faculty of Medical Science at the University of Oxford, who is one of a team of world-leading prevention experts at the Food for the Brain Foundation.

You may think that Alzheimer’s is “in the genes”, but this isn’t accurate; less than one in every hundred Alzheimer’s diagnoses are attributed to genes. Nor is it an inevitable consequence of ageing. 

The Food for the Brain charity focuses on helping people make simple, positive changes that will give your brain and memory an upgrade and dementia-proof your diet and lifestyle in the future. 

Eat fish and omega-3 fish oils (and/or vegan alternative) 

DHA (Docosahexaenoic acid) is an important omega-3 fatty acid and it is found in seafood and certain types of algae.

A study of almost half a million people from the UK’s Bio Bank found that those taking fish oil supplements had a seven per cent lower risk of dementia. The same was true for those with higher blood levels. Eating three servings of fish a week cuts Alzheimer’s risk by a third. The best fish are those that swim in cold water and eat other fish – salmon and mackerel. Sardines, anchovies, herring and kippers are also excellent. The best of all is caviar.

Algal or seaweed-derived DHA is just as good as that found in fish, so this is essential for any vegan wishing to protect their brain. You need at least 200mg a day, but ideally, double this amount. A very small amount of ALA (alpha-linolenic acid) in walnuts, chia and flax seeds, as well as colder climate leafy vegetables, does convert through to DHA so these foods are also important to eat on a daily basis.

Reduce sugar and refined carbs

Consumption of sugar, sugary junk food, sweetened drinks and white, refined bread, rice and pasta should be reduced. A 2022 US study reported that having a blood sugar level at the high end of the normal range, at age 35, increased a person’s risk of developing Alzheimer’s later in life by 15 per cent. So cutting back on sugar is the first of six simple changes that can cut your risk. 

Have more beans, fish, chicken, and less rice, pasta and potatoes. Eat eggs for breakfast or yoghurt, nuts, seeds and berries. Have oats instead of sugary cereals and oat cakes instead of bread. Our sugar expert Professor Robert Lustig, from the University of California, showed that sweet-toothed teenagers already have shrinking brains and worsening memory. It starts that young!

Take B vitamins

The first study that showed a reversal in the rate of brain shrinkage in people with pre-dementia gave a supplement of vitamin B6, B12, and folic acid. The study showed that the B vitamins halved the rate of brain shrinkage, and cut the shrinkage in the Alzheimer’s areas of the brain by nine times. The best drug to date has cut brain shrinkage by 2% with virtually no clinical benefit.

B vitamins are needed to help attach omega-3 to your brain. The next big breakthrough came when Professor David Smith’s group at the University of Oxford Unishowed that the omega-3 fats don’t work nearly so well without B vitamins – and the B vitamins don’t work in people with low intake of omega-3. You need both. 

“In those with sufficient omega-3 status B vitamins resulted in up to 73% less brain shrinkage and slowed memory decline,” says Professor Smith. One in three ended the trial with no clinical signs of dementia at all. Two other trials, in the Netherlands and Sweden, have confirmed that omega-3 and B vitamins are a dynamic duo, slowing down cognitive decline when both are sufficient.

The three critical B vitamins are vitamin B6, B12 and folic acid or folate which is found in green foods (think foliage). We recommend that older people supplement at least 10mcg of vitamin B12 a day, but the study gave 500mcg. Why? Because many older people absorb B12 less well. It needs stomach acid so those on antacid drugs often end up lacking B12.

The US National Institutes of Health researchers attribute 32% of the risk to an inactive lifestyle, 22 per cent to smoking, 22 per cent to lack of seafood or omega-3 and another 22 per cent to a raised blood homocysteine level, which is a measure of B vitamin status.

Eat more fruit and veg

Your brain spends a lot of energy thinking. This makes “exhaust fumes”, called oxidants, which age the brain. That’s why smoking is a big risk factor. Fruits, vegetables, herbs, spices and cacao are rich in brain-friendly antioxidants and polyphenols which improve circulation in your brain and help keep it young. So, while eating five servings of fruit and veg is good advice, having a handful of berries a day (blueberries being the best), and at least four servings of vegetables are better. Cacao in chocolate is also brain-friendly, but the sugar isn’t. Having a cocoa drink, made with cacao powder (without sugar) is the best of both worlds. Spices such as turmeric, cumin and chilli, cayenne or paprika are also great sources of polyphenols.

Keep active 

In the online test at Food For the Brain, we assess your “active mind”, “active body”, as well as “sleep and calm”. Your brain needs exercise. “For many people, the worst thing they can do for their brain is to retire,” says exercise expert Tommy Wood, Assistant Professor at the University of Washington. He has shown that your muscle mass predicts brain volume. 

“Exercise, especially resistance exercise, is important because it makes the brain do things that keep it healthy, such as growth and repair,” he says. “When they aren’t stimulated, the health of brain tissues deteriorates, with a knock-on effect on memory and thinking.” 

A study on trainee London taxi drivers learning “The Knowledge” – which involves memorising 26,000 streets – found that those who passed, compared to those that failed had literally built more brain tissue and connections.

And it’s not just physical exercise that does this, we also benefit from the mental exercise involved in activities like solving puzzles or learning a new language. “For many people, the worst thing they can do for their brain is to retire,” says Wood. “They lose much of the stimulation that kept it healthy.” It’s especially good to learn things you’re bad at. Those taking up learning musical instruments did better than professional musicians.

Sleep well

Just as you need a period of rest after exercise for muscles to recover, your brain needs sleep after a period of cognitive activity. The quantity and quality of sleep make a big difference. Sleeping only five hours, or nine or more hours doubles dementia risk. The optimal sleep duration is 7 hours and the optimal time for going to sleep is 10pm. “Owls”, who go to sleep late, have a higher risk. Also, the least disrupted sleep, the better. Stress also takes its toll.

Food For the Brain has tested 380,000 people with the free online Cognitive Function Test. An NHS and UCL study reported that nine in ten found the test useful. With the new Cognition app, which is a personalised, interactive brain upgrade programme that helps you make simple changes to dementia-proof your diet and lifestyle, you not only find out what simple changes will make the biggest difference to your risk but also get support along the way, guiding you step by step. The aim is to help you to dementia-proof your diet and lifestyle.

Risk for Alzheimer’s, which makes up two-thirds of dementia, can be picked up in mid-life. That sounds like bad news, but it isn’t, because most people can cut their risk by two-thirds just by making a few relatively simple diet and lifestyle changes in mid-life. 

Patrick Holford is a nutrition and mental health expert and the founder of the Institute for Optimum Nutrition Advice, VitaminC4Covid, and Food for the Brain.