By Joseph Brownstein, Contributing writer
Published: 01/22/2014 05:08 PM EST on LiveScience
Fish has long been hailed as "brain food," and now new data suggest fish contains ingredients that may contribute to brain health.
Researchers studied 1,000 postmenopausal women, looking at their levels of two fatty acids found in fish, called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
They found that women with significantly higher levels of the two fatty acids in their red blood cells also tended to have larger brains, and larger hippocampuses, the part of the brain associated with forming memories.
Studies have shown that in older adults, the brain generally shrinks with aging.
"If achieving a certain red blood cell level of the two major fish-derived omega-3 fatty acids could prevent or delay dementia, that would have huge mental health benefits, especially since levels can be safely and inexpensively raised through diet and supplementation," said study investigator James Pottala, an assistant professor of internal medicine at the University of South Dakota and a biostatistician at the Health Diagnostic Laboratory, Inc., a Virginia company that runs tests of blood levels of fatty acids.
In the study, researchers looked at MRIs of brain volume and red blood cell levels of DHA and EPA in 1,111 postmenopausal women who were part of the Women's Health Initiative Memory Study. They took measurements eight years later to determine the differences in the size of the women's brains, and found the link between fatty acid levels and brain volume. [6 Foods That Are Good For Your Brain]
"We found that a 2.7 percent larger hippocampus brain volume was associated with increasing from a low to a high EPA and DHA level," Pottala said. The levels seen in the women in the study could be obtained by eating non-fried 'oily' fish (such as salmon, tuna, herring or sardines) at least twice a week, and taking fish oil supplements, he said.
Pottala said the measures of fatty acids in the blood were done because an individual’s environment and genetics might affect how fish in the diet or fish oil supplements were metabolized.
While the brain volume data is encouraging, it is still only a waypoint in determining whether keeping levels of these fatty acids higher can actually stave off dementia.
Researchers hypothesize that the presence of EPA and DHA may help prevent shrinking in the brain, either because DHA is used in anti-inflammatory compounds that prevent cell death, or because it is used in the construction of the membranes of brain cells, but the exact reason for the connection requires further study.
Although the study was done in women, Pottala said similar results would be expected in men.
The hope is that the larger brain volumes seen in the study are an indication that fish consumption or fish oil supplementation can help ward off dementia or Alzheimer's disease. But that effect was not directly measured, and "has yet to be determined," Pottala told LiveScience,
The study is published today (Jan. 22) in the journal Neurology.