Shereen Jegtvig reports for Reuters, Jan. 22, 2014, that a new study suggests that omega-3 fatty acids protect the brain from the loss of volume that happens with normal aging and which is seen more severely in people with dementia.
A team of researchers led by Professor James Pottala found that older women with higher levels of omega-3 fatty acids in their blood had slightly less brain shrinkage than women with low fatty acid levels.
Pottala, an assistant professor at the University of South Dakota Sanford School of Medicine in Sioux Falls and chief statistician for the Health Diagnostic Laboratory in Richmond, Virginia, said, “The brain gets smaller during the normal aging process – about 0.5% per year after age 70, but dementia is associated with an accelerated and localized process of brain shrinkage.”
He and his colleagues analyzed data from the Women’s Health Initiative Memory Study to see whether omega-3s were associated with brain shrinkage in general, and in specific brain regions involved in memory and other cognitive processes.
The data covered 1,111 women who were, on average, 70 years old and had no signs of dementia at the beginning of the study. At that time, the amounts of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in their red blood cells were measured.
DHA accounts for 30% to 40% of the fatty acids found in brain cell membranes, and it’s especially concentrated near the synapses where the cells communicate with one another, Pottala and his colleagues note in their report, published in the journal Neurology.
Eight years after the women’s blood was tested, they underwent MRIs to measure the volume of gray matter and white matter in their brains. The researchers found that women with the highest EPA and DHA blood levels at the study’s outset:
- had brains that were about two cubic centimeters larger overall than women with the lowest levels.
- had larger hippocampus, a brain region critical to forming and storing memories — 2.7% larger in women who had fatty acid levels twice as high as the average. Of 13 specific brain regions the researchers looked at, the hippocampus was the only one where they saw a significant difference.
The analysis adjusted for other factors that could influence the women’s brain size, including education, age, other health conditions, smoking and exercise.
The researchers didn’t measure cognitive function, only brain volume, so they cannot say whether the size differences they saw had any link with differences in memory or dementia risk.
Pottala says higher blood levels of omega-3 fatty acids can be achieved by dietary changes, such as eating oily fish twice a week or taking fish oil supplements.
Since the study does not prove that blood levels of omega-3s are the cause of the brain-size differences observed, or that those differences have any effect on cognitive function, the researchers caution that more research is needed to know whether raising omega-3 levels would make any difference to brain health.
Omega-3s are also good for heart health. The American Heart Association recommends that Americans eat two servings a week of fatty fish rich in omega-3 fatty acids, like sardine and wild salmon.
However, other research has raised questions about whether high levels of omega-3s may raise the risk of prostate cancer.