Among people over 65, consumption of tuna/other fish is associated with preserved blood flow to the brain, according to a 2008 research report in the journal Neurology.
“Silent” brain infarcts – tiny strokes that are not obvious – are very common with advancing age. If a group of people 65 and older is MRI scanned and found to have no strokes, MRI scans performed five years later will show tiny strokes in 20% of them. Almost 90% of these new strokes are simply incidental findings without clinically evident stroke or transient ischemic attack.
As the authors point out:
Subclinical infarcts and white matter abnormalities are considered to be of vascular origin, presumably resulting from occlusion of small arteries in the brain and subsequent ischemia.
These subclinical strokes, along with brain white matter abnormalities, are not benign. They are associated eventually with impairment in thinking and behavior, and with higher risk of future obvious stroke.
Eating tuna or other broiled or baked fish tends to raise plasma omega-3 fatty acid levels and is associated with lower stroke risk and dementia and Alzheimer disease. Researchers wondered if fish consumption affected the risk of subclinical brain infarcts or other subclinical brain abnormalities.
Scientists studied 3,660 participants over 65 years old in the Cardiovascular Health Study, by MRI scanning, lab testing, physical exam, and food frequency questionnaire. Five years later, 2,313 were rescanned. Hospital and clinic records were reviewed. Participants were men and women in four U.S. communities. Fish intake was classified as to whether tuna, other broiled or baked fish, and fried fish or fish sandwiches (fish burgers). In a subset of participants, blood levels of omega-3 fatty acids were measured.
Conclusions of the Scientists
Among older adults, modest consumption of tuna/other fish, but not fried fish, was associated with lower prevalence of subclinical infarcts and white matter abnormalities on MRI examinations. Our results add to prior evidence that suggest that dietary intake of fish with higher eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA] content, and not fried fish intake, may have clinically important health benefits.
…the results of the present article support the growing evidence that the type of fish meal consumed is important for obtaining the health benefits of fish consumption.
The fish with higher omega-3 fatty acids, such as EPA and DHA, are the cold-water fatty fish such as albacore tuna, salmon, trout, sardines, anchovies, herring, halibut, sea bass, swordfish, and mackerel. These are sometimes referred to as dark meat fish or oily fish. These are the same types of fish most closely associated with lower rates of coronary artery disease and sudden cardiac death.
The types of fish used in fish sticks, fish burgers, and other fried fish meals are typically low in omega-3 fatty acids.
If you choose to eat fish for the health benefits, aim for two servings per week of cold-water fatty fish. The Friday night all-U-can-eat fried catfish buffet doesn’t cut it.
Steve Parker, M.D.
Reference: Virtanen, J.K., et al. Fish consumption and risk of subclinical brain abnormalities on MRI in older [U.S.] adults. Neurology, 71 (2008): 439-446.