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 in a new study.
The results may suggest that omega-3s protect the brain from
the loss of volume that happens with normal ageing and is seen more severely in
people with dementia, the researchers say. "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 localised process of brain shrinkage,"
said James Pottala, who led the study.
your brain needs Omega-3
Pottala is 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.
He and his colleagues analysed 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.
Red blood cell levels of the omega-3s are good indicators of
how much a person has consumed, the researchers add.
The researchers used an omega-3 index to describe the fatty
acid levels seen among women in the study and to divide them into four groups:
women with the highest levels had an average index reading of around 7.5%,
while women with the lowest levels had an average of 3.4%.
Eight years after the women's blood was tested, they
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 centimetres
larger overall than women with the lowest levels.
In addition, the hippocampus, a brain region critical
to forming and storing memories, was 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.
The authors acknowledged other limitations in their report,
including that they did not look at whether the women's omega-3 consumption had
changed over time.
It's possible that some of the participants had changed
their diets or started taking fish oil or other forms of omega-3 fatty acids,
Pottala told Reuters Health in an e-mail.
But in previous study, he and his colleagues showed red
blood cell EPA and DHA levels and people's dietary fish intakes generally don't
change over time."If some subjects in our MRI study began taking fish
oil supplements, then the reported benefits would be underestimated,"
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
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