“People with lower blood levels of omega-3 fatty acids had lower brain volumes that were equivalent to about two years of structural brain aging,” said Dr. Zaldy S. Tan, MD, MPH of the University of California, principal author of a new study published in the medical journal Neurology. Those with a diet lacking in Omega-3 fatty acids (found in fish, flax seed and other foods) also performed worse on tests of their memory and thinking abilities, the study found.
Omega-3 fatty acids include the nutrients called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), nutrients commonly found in fish, as well as in flax seed, walnuts and other foods.
The new study, by Zaldy S. Tan, MD, MPH, of the Easton Center for Alzheimer’s Disease Research and the Division of Geriatrics, University of California at Los Angeles and colleagues, was published in the February 28, 2012 issue of Neurology®, the medical journal of the American Academy of Neurology, a non-profit association of more than 25,000 neurologists and neuroscience professionals.
However, the new study may have been the first of those examining the effect of dietary Omega-3 on brain health to measure the extent of Omega-3 found in participants by entirely objective means (through blood tests), rather than through questionnaires which rely upon participants’ memories to report the extent of Omega-3 in their diets. In addition, the new study used MRI brain scans to measure brain shrinkage, and tested memory and thinking skills through standard tests.
The new study was part of the larger, federally funded Framingham Heart Study, supported by the National Heart, Lung, and Blood Institute and the National Institute on Aging.
The Study; Methodology
The study included 1,575 people of an average age of 67. All of the participants were free of dementia, a condition that typically includes memory loss.
The participants underwent MRI brain scans to measure total brain volume, as well as blood tests, which measured the levels of omega-3 fatty acids (including DHA and EPA) found in their red blood cells. The researchers used a measure that looked at the level of omega-3 fatty acids in red blood cells over three months.
In addition, the participants were weighed to measure their body mass, and were given a battery of standard tests that measured their level of mental functioning and memory.
The researchers then examined and ranked the level of omega-3 fatty acids (DHA) in the participants’ blood. Those who scored in the bottom 25% in omega-3 fatty acid (DHA) levels were compared to the rest of the study participants.
The researchers found that the study participants whose DHA levels were among the bottom 25 percent of the participants had lower brain volume compared to people who had higher DHA levels.
In fact, the differences in brain size were equivalent to approximately two years of normal brain aging, as noted (quote above) by the study’s lead author, Dr. Zaldy Tan, a visiting associate professor in the geriatrics department of the University of California, Los Angeles, and a member of the UCLA Easton Center for Alzheimer’s Disease Research.
As people age, brains normally shrink, he explained. However, those with high levels of Omega-3s in their blood seemingly had slowed the normal brain shrinkage by the equivalent of about two years of normal aging.
In addition, the study found that participants with levels of all omega-3 fatty acids in the bottom 25 percent also scored lower on neuropsychological tests of visual memory and executive function, such as problem solving, multi-tasking and abstract thinking.
Conclusions & Implications
“Lower RBC [red blood cell] DHA [Omega-3] levels are associated with smaller brain volumes and a “vascular” pattern of cognitive impairment even in persons free of clinical dementia,” the study authors concluded.
However, the study did not measure how much fish or other omega-3-rich foods the participants consumed to reach the omega-3 level found in those not in the bottom 25% of participants. Dr. Tan told the Wall Street Journal that there is no universally accepted target level for omega-3 in the blood. The test used in the study to measure Omega-3 levels is not commercially available, he said.
The most recent U.S. dietary guidelines, released last year, recommend at least two servings of fish per week. Harvard Health Publications, by Harvard Medical School, concurs that two servings of fish per week would have health benefits. The Wall Street Journal reports that some doctors and diet experts recommend that patients eat fish three times a week or take fish-oil supplements to get enough Omega-3 fatty acids for health benefits.
Several studies, including a recent study by the Mayo Clinic, have shown that diets rich in fish, such as the Mediterranean diet, lower people’s risks of developing heart problems or having a stroke. See, for example, our previous report on a study that analyzed 15 studies measuring the potential relationship between fish consumption and incidence of stroke in a combined total of 383,838 participants: Can Eating Fish Reduce Your Risk of Stroke?
Some studies, including one conducted on early participants in the ongoing Framingham study (which started in 1948), have suggested that eating fatty fish such as salmon and tuna can lower the risk of Alzheimer’s disease and other dementias. However, not all studies of these studies have found an association between Omega-3s and Alzheimer’s disease, according to researchers.
One reason for the inconsistent results of these studies may be that, unlike the new study, most of them have relied on questionnaires to determine the frequency of dietary intake of different foods by the participants. Relying upon participants’ memories, this may not be an accurate measure of the food they actually consumed over a period of time.
See related HelpingYouCare™ reports on:
- Diet & Nutrition: Physical Wellness;
- Exercise: Physical Wellness;
- Sleep, Hygiene, Quit Smoking & Other Healthy Practices: Physical Wellness; and
- Other Areas of Wellness.
To learn more about memory problems, the American Academy of Neurology invites you to visit their website: http://www.aan.com/patients.
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