Five years ago, researchers gave people diet questionnaires and MRI brain scans, and compared the results of both.
And that U.S.-Finnish team found fewer “silent” brain abnormalities in the brains of people who reported eating fish frequently (Virtanen JK et al. 2008).
Then, two years ago, a similar study linked fish-rich diets (once a week or more) to maintenance of gray matter in key, dementia-related brain areas (Raji C et al. 2011).
As lead author Cyrus Raji, M.D., Ph.D., put it, “… people who consumed baked or broiled fish at least one time per week had better preservation of gray matter volume in brain areas at risk for Alzheimer’s disease.” (UPMC 2011)
The fried fish exception
As in studies of stroke risk, the findings of brain benefit from diets rich in fish – by far the best food sources of omega-3 fatty acids – did not apply to fried fish.
In contrast, eating fried fish was not linked to protection of gray matter or cognitive capacities.
The fried-fish exception to the “fish is brain healthy” flows from its oil-soaked breading, cooked in cheap frying oils (soy, cottonseed, etc.).
Standard frying oils are very high in omega-6 fats, which compete with omega-3s and tend to promote and sustain inflammation … a major risk factor for stroke and heart disease (see “America’s Sickening ‘Omega Imbalance’”” and “Heart Risk Cut by Fish but Frying it Outweighs the Benefit”).
However, studies that rely no people’s self-reported diets to estimate omega-3 intake are not fully reliable.
Now, the same Harvard-Finland team reports encouraging, exceptionally credible results from a new MRI brain-scan study.
MRI brain-scans link higher omega-3 blood levels to healthier brains
The new MRI study involved 3,660 participants in the U.S.-based Cardiovascular Health Study, all aged 65 and older.
This time, instead of relying on people’s self-reported diets to estimate their omega-3 intake, the Harvard-Finland team measured participants’ omega-3 blood levels.
The volunteers underwent brain scans to detect two signs of age-related brain damage:
Changes in the brain’s white matter, essential to mental function.
Brain infarct, or small lesions, which fog thinking and promote dementia and stroke.
Five years later, about two in three of the original participants (2,313 people) underwent follow-up MRI scans.
Compared to participants with the lowest omega-3 blood levels, the people with the highest omega-3 levels averaged 40 percent fewer small brain lesions (infarcts).
Likewise, a comparison of scans and blood-test results linked higher blood levels of omega-3s to less white matter loss.
As the authors wrote, “Our results support the beneficial effects of fish consumption, the major source of long‐chain omega‐3s, on brain health in later life.” (Virtanen JK et al. 2013)
Given the long term nature of brain decline it makes sense to keep the most omega-3-dependent organ supplied with these essential, protective nutrients, lifelong.
Why do these findings matter?
Small brain infarcts (lesions) – which can only be detected by brain scans – are found in about 20 percent (one in five) of apparently brain-healthy elderly people.
As they accumulate in number, brain infarcts tend to fog memory and thinking and promote dementia and stroke.
White matter forms conduits that connect major brain regions responsible for memory, sensory processing, and decision-making, and enables them to coordinate activity and share information.
In young, healthy brains, signals between its major functional regions are readily transmitted by white-matter conduits.
As we age, those conduits decline. Depending on the networks involved, the results include impaired memory, reasoning, and other advanced cognitive functions.
The study was supported by the U.S. National Heart, Lung and Blood Institute, the U.S. National Institute of Neurological Disorders and Stroke, the U.S. National Institute on Aging, and the Finnish Cultural Foundation.
Raji C et al. Regular Fish Consumption Is Associated with Larger Gray Matter Volumes and Reduced Risk for Cognitive Decline in the Cardiovascular Health Study Neuroradiology (Cognition II); Friday, December 02 2011 Accessed at http://rsna2011.rsna.org/search/event_display.cfm?em_id=11008757 Radiological Society of North America (RSNA).
University of Pittsburgh School of Medicine (UPMC). Eating Fish Reduces Risk of Alzheimer’s Disease, Pitt Study Finds. Nov. 30, 2011. Accessed at http://www.upmc.com/MediaRelations/NewsReleases/2011/Pages/Eating-Fish-Reduces-Risk-Alzheimers.aspx
Virtanen JK, Siscovick DS, Longstreth WT Jr, Kuller LH, Mozaffarian D. Fish consumption and risk of subclinical brain abnormalities on MRI in older adults. Neurology. 2008 Aug 5;71(6):439-46. doi: 10.1212/01.wnl.0000324414.12665.b0.
Virtanen JK, Siscovick DS, Lemaitre RN, Longstreth WT, Spiegelman D, Rimm EB, King IB, Mozaffarian D. Circulating Omega-3 Polyunsaturated Fatty Acids and Subclinical Brain Abnormalities on MRI in Older Adults: The Cardiovascular Health Study. J Am Heart Assoc. 2013 Oct 10;2(5):e000305.