WEDNESDAY, Jan. 22, 2014 (HealthDay News) -- The more you consume the omega-3 fatty acids found in fish oils, the less likely you are to lose as many precious brain cells as you age, a new study suggests.
More research is needed, however, to understand both why this happens and how much of the nutrient brings about the most benefit, the researchers said.
"Our findings support the idea that a higher omega-3 status from fish or supplements is good for brain health," said study author James Pottala, an assistant professor in the department of internal medicine at the University of South Dakota's Sanford School of Medicine.
According to the study, which was published online Jan. 22 in the journal Neurology, the researchers tested levels of omega-3 fatty acids in the red blood cells of more than 1,000 older women. Eight years later, the women had MRI scans that measured their brain volumes. At the time of the scans, the women were an average of 78 years old.
Participants whose omega-3 levels were twice as high had a 0.7 percent higher brain volume. "The results suggest that the effect on brain volume is the equivalent of delaying the normal loss of brain cells that comes with aging by one to two years," Pottala said.
Higher omega-3 levels also were associated with greater volume in the hippocampus, the region of the brain in which the memory-robbing disease Alzheimer's first attacks.
The study offers valuable information, said Dr. Gregory Cole, associate director of the Mary S. Easton Center for Alzheimer's Disease Research at the University of California Los Angeles.
"[The study] has a large number of subjects with an objective measure -- the measure of brain volume," Cole said. "Studies that measure things like [memory and thinking] are not as concrete. People have good days and bad days, but when you measure brain volume you get a pretty repeatable measure."
It's also a plus that the participants are all the same gender, so there is no gender variation in brain size to factor in, Cole said.
The study's findings are intriguing, said Dr. JoAnn Manson, chief of the division of preventive medicine at Brigham and Women's Hospital in Boston. "[But] the results should be interpreted cautiously because it's an observational study and not a randomized clinical trial looking at the relationship between omega-3 intake and changes in brain volume," she said.
Although the study showed an association between omega-3 intake and improved brain health, it didn't necessarily prove a cause-and-effect link.
Manson is the principal investigator in a study involving more than 20,000 adults across the United States looking at whether taking daily dietary supplements of vitamin D or omega-3 fatty acids reduces the risk for certain diseases.
The study involves memory testing as well, Manson said. "We'll have some more information in another two to three years, and I think that will be important to see if increasing supplementation with omega-3s is having a clinical impact on [brain] function," she said.
Cole said clinical trials are the only way to find out if high omega-3 consumption really increases brain volume and reduces the risk for dementia.
"This is pretty believable. This is a solid finding," he said. "The question is: How can you translate this into [effectiveness] in people? Will it really work to protect peoples' brains?"
In the meantime, people who want to boost their omega-3 intake can eat nonfried 'oily' fish such as salmon, herring, tuna and sardines. The American Heart Association recommends eating at least two servings of fish a week.
Find out more about omega-3 fatty acids at the American Heart Association.