A Mediterranean diet high in vegetables, nuts and seafood could reduce the risk of getting dementia by almost a quarter.
Researchers looked at almost 60,300 people aged over 40 in the UK who were asked about their typical diet over 24 hours.
Their answers were rated for closeness to the healthy Mediterranean diet, popular in countries like Italy and Spain, which includes fruit and vegetables, pulses and a moderate amount of wine.
The third of people who scored most highly for a Mediterranean-style diet were 23 per cent less likely to develop dementia than the third who scored most poorly.
A Mediterranean diet is believed to reduce inflammation in the body and brain, which is linked to dementia.
A Mediterranean diet is believed to reduce inflammation in the body and brain, which is linked to dementia (stock image)
Dr Claire McEvoy, a co-author of the study from Queen’s University Belfast, said: ‘Most people are unaware that keeping a healthy diet and lifestyle can protect memory and thinking abilities during ageing.
‘This important study shows that eating more vegetables, fruits, fish and olive oil and less processed food, sugary food and red meat, could help to reduce the risk of future dementia in our UK population.’
There are currently around 900,000 people living with dementia in the UK, with no known cure, so ways to prevent the disease in our everyday lives are a major focus of scientific research.
Previous studies have shown mixed results on whether a Mediterranean diet reduces the risk of dementia.
However this is one of the largest conducted, including 882 people who were diagnosed with the condition when their health was tracked for an average of nine years.
Each person in the study completed one to five questionnaires at different points in time on what they had eaten in the previous 24 hours, to give an idea of their usual diet.
Their selections, from a list of more than 200 foods and 32 drinks, plus the portions they had eaten, were then given a score out of 13 for how close they were to the Mediterranean diet.
For example, someone eating the required 400 grams of vegetables would score one point for this food type, but only 0.5 points if they ate 200 grams.
The 13 categories scored included seafood, legumes and nuts, with people scoring more highly if they did not eat too much of certain items like red meat and sugary drinks.
Under this scoring system, the third of people who scored most highly were 23 per cent less likely to develop dementia compared to the third with the lowest scores.
Under two slightly different scoring systems, where people got points only if they reached a certain amount of each Mediterranean food, like scoring one point for 400 grams of vegetables, a lower risk of dementia was also seen.
This was a 14 per cent lower risk for the third of people who scored highest for a Mediterranean diet, compared to the third who scored lowest.
The researchers used different ways of scoring diet to check their result was reliable.
They also took into account factors like people’s age, sleep levels and exercise, which could also affect their risk of dementia.
It is possible that people in the early stages of dementia do not remember to eat as healthily – making it look as if an unhealthy diet causes dementia, when in fact the disease leads to having a poorer diet.
But the result was still seen in people who were followed up for the longest period in the study, making this less likely to be the case.
The study, led by Newcastle University and published in the journal BMC Medicine, found a reduced risk of dementia in people who followed a Mediterranean diet, even when they had a higher genetic risk of the condition.
This was based on a detailed profile of almost a quarter of a million genetic differences which can increase the risk of dementia.