A new diet could more than halve a person's risk of developing Alzheimer's disease, according to new research.

Experts said the diet, known by the acronym MIND, could reduce the risk of the illness even if it not meticulously followed.

The 'Mediterranean-DASH Intervention for Neurodegenerative Delay' (MIND) diet includes at least three daily servings of wholegrains and salad – along with an extra vegetable and a glass of wine.

The new diet could more than halve a person's risk of developing Alzheimer's disease, new research has found, and even has an effect when a person doesn't follow it meticulously

These 'brain-healthy foods' lowered the risk of Alzheimer's by 53 per cent in those who stuck to the diet rigidly.

For those that followed it moderately well, it lowered the risk by about 35 per cent.

Professor Martha Morris, a nutritional epidemiologist of the Rush University Medical Centre in Chicago, said: 'One of the more exciting things about this is that people who adhered even moderately to the MIND diet had a reduction in their risk for Alzheimer's disease.

'I think that will motivate people.'

Professor Morris and her colleagues developed the MIND diet based on years of past research about what foods and nutrients have good and bad effects on the functioning of the brain.

This is the first study to relate the MIND diet to Alzheimer's disease.

'I was so very pleased to see the outcome we got from the new diet,' she said.

The MIND diet is a hybrid of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets, both of which have been found to reduce the risk of cardiovascular conditions, like high blood pressure, heart attack and stroke.

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Some researchers have found that the two older diets provide protection against dementia as well.

In the latest study, the MIND diet was compared with the two other diets.

People with high adherence to the DASH and Mediterranean diets also had reductions in Alzheimer's disease— 39 per cent with the DASH diet and 54 per cent with the Mediterranean diet.

However, the diets had negligible benefits when people only adhered to it moderately.

Professor Morris added that the MIND diet is also easier to follow than the Mediterranean diet, which calls for daily consumption of fish and three to four daily servings of fruits and vegetables.

The MIND diet has 15 components, including 10 'brain-healthy food groups' — green leafy vegetables, other vegetables, nuts, berries, beans, whole grains, fish, poultry, olive oil and wine.

It also has five unhealthy groups that comprise red meats, butter and stick margarine, cheese, pastries and sweets, and fried or fast food.

The MIND diet includes at least three servings of wholegrains, a salad and one other vegetable every day — along with a glass of wine.

It also involves snacking most days on nuts and eating beans every other day or so, poultry and berries at least twice a week and fish at least once a week.

Dieters must limit eating the designated unhealthy foods, eating less than one tablespoon of butter a day and eating cheese, fried or fast food to less than once a week.

Limiting these foods is essential to have a real shot at avoiding the devastating effects of Alzheimer's, according to the study.

Berries are the only fruit specifically to make the MIND diet.

Professor Morris said: 'Blueberries are one of the more potent foods in terms of protecting the brain,' adding that strawberries have also performed well in past studies of the effect of food on cognitive function.

The diet suggests 10 brain-healthy foods including wholegrains, salad, vegetables, berries, nuts, beans, olive oil, poultry and fish

The MIND diet was not an intervention in this study, however; researchers looked at what people were already eating.

Participants earned points if they ate brain-healthy foods frequently and avoided unhealthy foods.

The one exception was that participants got one point if they said olive oil was the primary oil used in their homes.

The study enlisted volunteers already participating in the ongoing Rush Memory and Aging Project (MAP), which began in 1997 among residents of Chicago-area retirement communities and senior public housing complexes.

An optional 'food frequency questionnaire' was added from 2004 to February 2013, and the MIND diet study looked at results for 923 volunteers.

The diet advises limiting butter to one tablespoon a day and limiting cheese, pastries, sweets and fast or friend food to once a week

A total of 144 cases of Alzheimer's disease developed in this group of people.

The disease, which takes a devastating toll on cognitive function, is not unlike heart disease in that there appear to be 'many factors that play into who gets the disease,' including behavioral, environmental and genetic components, Professor Morris said.

She continued: 'With late-onset Alzheimer's disease, with that older group of people, genetic risk factors are a small piece of the picture.'

Past studies have yielded evidence that suggests what we eat may play a significant role in determining who gets the illness and who doesn't, Professor Morris added.

When the researchers in the new study left out of analysis of participants who changed their diets somewhere along the line — say, on a doctor's orders after a stroke — they found there was a stronger link between the MIND diet and more favourable outcomes in terms of Alzheimer's disease.

The diet's developer said blueberries are 'one of the more potent foods in terms of protecting the brain'

He said: 'That probably means that people who eat this diet consistently over the years get the best protection.'

In other words, it looks like the longer a person eats the MIND diet, the less risk that person will have of developing Alzheimer's, Professor Morris said.

As is the case with many health-related habits, including physical exercise, she said, 'You'll be healthier if you've been doing the right thing for a long time.'

She added that the study did not establish a cause and effect relationship between the MIND diet and a lowered risk of Alzheimer's.

Other studies on different populations would need to be carried out to do this, she said.