This may be the first time you've heard of it, but diets rich in choline may help protect your brain from the affects of ageing.

The nutrient from the B vitamin family is found in foods like chicken, eggs and saltwater fish as well as legumes such as kidney beans.

Researchers at Boston University found people who gotplenty of choline in their diets performed better on memory tests and were less likely to show brain changes associated with dementia.

The findings add to evidence that your lifetime diet may make a difference in how your brain ages, said senior researcher Dr Rhoda Au.

However, she cautioned against looking to any one nutrient as a magic bullet against dementia.

'I think the message is that eating a healthy, balanced diet in mid-life is important,' she said.

Previous research has found a Mediterranean-style diet, which includes fish, vegetables and olive oil, might have a protective effect.

For the latest study, Dr Au combed through the results from a long-running heart health survey.

Nearly 1,400 adults aged 36 to 83 answered dietary questionnaires between 1991 and 1995. Then, between 1998 and 2001, they underwent tests of memory and other cognitive abilities and had MRI brain scans.

The study found, men and women in the top quarter for choline intake performed better on the memory tests than those in the bottom quarter.

This held true even when factors including education and fat and calorie intake were taken into consideration.

People with higher choline intake at the outset were also less likely to show areas of 'white-matter hyperintensity' in their MRI brain scans.

Those age-related areas are thought to be a sign of blood vessel disease in the brain, which may signal a heightened risk of stroke or, eventually, dementia.

Dr Au said people who didn't consume much choline would not notice an 'appreciable difference' day to day.

However, she said the findings suggest that people with lower choline intakes were more likely to be on a 'pathway' toward mental decline than their counterparts with higher intakes.

While the study does not conclusively prove choline protects the memory there is reason to believe that choline matters. The nutrient is a precursor to the brain chemical acetylcholine, which plays a key role in memory and other cognitive functions; low acetylcholine levels are associated with Alzheimer's.

Dr Au concluded that more research was needed in this promising area.

Experts generally recommend that men get 550mg of choline per day, while women should get 425mg.

Sources: The Daily Mail Online;