You may know someone with dementia, a grandparent or an older relative. You might have heard about it in a news story. In 2023, Die Hard actor Bruce Willis, was diagnosed with frontotemporal dementia at just 68. In 2022, 39-year-old Thor actor, Chris Hemsworth, stepped back from acting to spend time with his family and focus on his health after learning he has two copies of a gene, inherited from both parents, that increase his risk of Alzheimer’s.
There is no cure for dementia and it is the most feared health condition for people over 55, according to Alzheimer’s Research UK. But 40 per cent of cases could be prevented or delayed, according to a 2020 Lancet commission and there’s mounting evidence that a healthy diet can help.
More than 55 million people worldwide have dementia and by 2050, that number is expected to rise to 139 million. Dementia is not a single disease but a collection of symptoms resulting from damage to the brain. Changes in the brain may occur years, or even decades, before symptoms appear. The most common cause is Alzheimer’s disease but there are other forms of dementia and it can result from brain injuries or stroke. Symptoms include memory loss and problems with reasoning, communicating and the ability to carry out everyday tasks. It can affect feelings of hunger, thirst and even the ability to swallow.
Several factors increase the risk of dementia: genetics, obesity, diabetes, high cholesterol, high blood pressure and heart disease. We can’t change our genes, but we can reduce other risk factors with lifestyle and dietary changes.
Obesity in mid-life increases dementia risk, especially among those who store fat on their tummy. One long-term study, following 10,000 people, found that being obese in mid-life increases the risk by 74 per cent and being overweight increases it by 35 per cent. Vegans tend to weigh less than meat-eaters and the huge EPIC-Oxford study found that they also gain significantly less weight as they age.
Diabetes increases the risk of heart disease and stroke, but also increases the risk of all types of dementia by 73 per cent and Alzheimer’s by 56 per cent, according to a review of 28 studies. Ninety per cent of people in the UK with diabetes have type 2 and a vegan diet reduces the risk of that by up to 50 per cent and can even help reverse it.
Another study, looking at cholesterol and dementia in 1.8 million people over two decades, found that high cholesterol levels in midlife increase the risk of dementia more than a decade later. Again, vegans tend to have lower cholesterol levels. It’s the same story for blood pressure and heart disease. The more risk factors you have, the higher your dementia risk. The Whitehall II cohort study, following 10,095 British civil servants for 32 years, found having two or more chronic conditions was linked to a 2.4-fold higher risk of dementia.
The good news is these risk factors can be prevented or reversed by making dietary and lifestyle changes. A review of 21 studies found that following a healthy diet was linked to a 55 per cent lower risk of Alzheimer’s. The Finnish Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study, looking at people in their mid-fifties, then again at 70 and 78, found that healthy dietary changes in midlife, such as switching to healthier fats, increasing vegetables and decreasing salt and sugar, were linked to a 59 per cent lower risk of dementia. Individual nutrients made little or no difference – it was the whole diet that reduced the risk.
The Dietary Approaches to Stop Hypertension (DASH) diet was designed to lower blood pressure. Researchers at Rush University in Chicago combined it with the Mediterranean diet to create their own Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet. It features fruit and vegetables, wholegrains, pulses, nuts and extra-virgin olive oil and contains very little (if any) red meat, butter, pastries, sweets and fried/fast food – all best avoided.
The MIND diet includes some fish and poultry but studies showing how vegetarians have a lower risk of dementia provide reassurance that excluding fish and chicken does not harm brain health. There are healthier, more sustainable sources of omega-3s than fish oils, such as ground flaxseed, chia or hemp seeds, walnuts and algae-based supplements. Poultry is not healthy either as modern chickens provide more energy from fat than protein.
The MIND diet emphasises green leafy vegetables and berries – known to protect brain health. One study, following 960 older people for nearly five years, found those who ate the most brain-healthy foods (based on the MIND diet) had a slower rate of cognitive decline equivalent to being 7.5 years younger than those eating the least. For green leafy vegetables, the rate of decline among those eating just one or two servings a day equated to being 11 years younger compared with those who rarely or never ate green leafy vegetables.
Green leafy vegetables provide folate, vitamin E and other nutrients linked to brain health. They contain carotenoids and polyphenols, which have potent antioxidant and anti-inflammatory activities. Inflammation is a key factor thought to increase the risk of dementia.
A diet, packed with meat, dairy, processed and sugary foods, promotes chronic conditions linked to dementia and causes detrimental changes in gut bacteria (microbiome) that can trigger inflammation. The Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) study in Greece followed 1,000 people for three years and found that those eating the most pro-inflammatory foods were three times more likely to develop dementia.
Some studies suggest low levels of vitamins D and B12 are linked to an increased risk of dementia. Ensure a regular intake of B12 and consider taking a vitamin D supplement in winter (everyone should do this!). Regular physical activity, getting enough sleep, avoiding smoking and keeping alcohol within recommended limits are also important to reduce your risk of dementia.