Elderly people with higher levels of certain vitamins and omega 3 fatty acids in their blood score better on mental acuity tests than those who eat junk food, a new study has shown.

The study published in Neurology, the journal of the American Academy of Neurology, also showed that eating better could help reduce the brain shrinkage commonly associated with Alzheimer's disease.

"This approach clearly shows the biological and neurological activity that's associated with actual nutrient levels, both good and bad," says Maret Traber, a principal investigator at the Linus Pauling Institute and study co-author.

Researchers note the positive effects of high levels of vitamins B, C, D and E, as well as the healthy oils most commonly found in fish, on mental quickness and brain size.

Study co-author Gene Bowman of the Oregon Health and Science University adds while results needed to be confirmed, "It is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet."