People who enjoy a diet high in Omega 3 fatty acids have less brain shrinkage and better cognitive abilities, while those who indulge in food high in trans fats show the opposite, a new study suggests.

A diet rich in Omega 3s, primarily found in fish, as well as B, C, D and E vitamins appears to ward off brain shrinkage associated with conditions such as Alzheimer's and dementia, according to new research from Oregon Health and Science University in Portland. Study participants who ate both large quantities of fish, healthy oils and antioxidant vitamins received high scores in mental thinking tests.

Conversely, those who consumed foods high in trans fats — largely found in packaged, fried and fast foods — showed evidence of increased brain shrinkage and had lower scores on memory tests.

One hundred and four people with an average age of 87 were involved in the study, which measured their blood nutrient levels as well as memory and thinking skills. Forty-two of the study participants had their brain volumes measured using MRI. All of the participants were not at high risk of memory problems.

The scientists found that seven per cent were low in vitamin B12 and 25 per cent had too little vitamin D in their systems. While age, education and health issues such as high blood pressure accounted for the bulk of the variations in cognitive performance, researchers believe that the nutrient levels in the bloodstream of the study’s participants accounted for 17 per cent in the variations of thinking and memory scores and 37 per cent of the variations in brain volume.

"These results need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet," said Gene Bowman, an author of the study, in a release.

"The vitamins and nutrients you get from eating a wide range of fruits, vegetables and fish can be measured in blood biomarkers," said Maret Traber, a principal investigator with the Linus Pauling Institute and co-author on the study. "I'm a firm believer these nutrients have strong potential to protect your brain and make it work better."

The study was published in the Dec. 28 online issue of Neurology.