Eating fish appears to knock a few years off your mental age - in a good way.

Elderly people who ate fish at least once a week had the mental functioning of a person three years younger than their chronological age, while those who ate fish twice weekly or more turned the clock back four years.

“It appears as if it’s helping to keep the brain healthy,” said Dr. Martha Clare Morris of Rush University Medical Center in Chicago.

Seafood is rich in omega-3 acids. One of these acids in particular, docosahexaenoic acid (DHA), is essential for the development of the brain in early life, she explained. More recent research suggests DHA may be key for people at the other end of the age spectrum as well, she added.

“It does look like it’s as important as well in old age, or maybe just in general, for brain functioning,” Morris said.

In the current study, she and her colleagues followed 3,718 people 65 and older for six years. All were interviewed at home three times in the course of the study.

Participants who ate fish once a week showed a 10% slower decline in their mental function, equivalent to a three-year reduction in mental age, while eating fish twice a week or more slowed the decline by 13%, equivalent to four years.

A separate analysis of omega-3 fatty acid consumption did not find it affected cognitive function, but Morris said this may have been because their information was not precise enough. She and her colleagues have launched another study to look specifically at the effect of these nutrients on mental function.

Nevertheless, she adds, the findings do suggest eating fish protects the brain, either through its own fatty acid content or by knocking foods high in saturated fat, like red meat, off the menu.

SOURCE: Archives of Neurology, December 2005.