The results of two epidemiological (population) studies, both published earlier this month, lend strong support to the hypothesis that omega-3s are brain-health protectors.
Better yet, the authors of one of the new reports based their conclusions on the subjects' actual blood levels of omega-3s, rather than relying on participants' memories of their fish consumption.
This is important, since, as Vital Choice science advisor William E. Lands, Ph.D. is fond of saying, “the tissue is the issue.” In other words, studies that rely on people's recollections are useful primarily as guideposts for more reliable blood-based research (In a very real sense, blood cells are “tissue,” and their omega-3 content is considered the most accurate barometer for omega-3 intake).
Dutch study links fishy diets to greater delays in mental decline
Dr. Boukje Maria van Gelder led a team from the Dutch National Institute for Public Health and the Environment, who analyzed dietary intake data collected from 210 men without Alzheimer's disease (van Gelder BM et al 2007).
The men, who ranged in age from 70 to 89, completed diet surveys in 1990. Dr. van Gelder's group used the men's self-reported fish consumption to estimate their intake of long-chain marine omega-3s (EPA and DHA).
The participants' cognitive functions were tested twice—once in 1990, at the beginning of the study, and again in 1995—to capture any changes in the men's mental status.
Dr. van Gelder's new analysis of this data indicates that the biggest fish eaters among the men suffered significantly less cognitive decline compared with men who ate little or no fish.
Importantly, the association between fish consumption and mental status was dose-dependent: that is, the more fish men in the study ate, the less their mental status declined.
Specifically, the men who consumed an average of about 400 mg of omega-3s per day enjoyed significantly less cognitive decline, compared with men who reported consuming amounts of fish that would deliver only about 20 mg per day.
This means that the amount recommended to reduce the risk of dying from cardiovascular disease should also help prevent mental decline.
As the Dutch researchers noted, 400 mg is the amount in two servings of average fish, which is the minimum number of servings the American Heart Association recommends eating every week to prevent cardiovascular deaths. Fatty fish like salmon are much richer in omega-3s.More good omega-3 news
In the second study, researchers analyzed data collected from 2,251 men and women living in Minneapolis (average age 57) with some degree of heart disease, who'd participated in the Atherosclerosis Risk in Communities (ARIC) Study.
From 1987 through 1989, Minnesota researchers conducting the AIRC study analyzed the levels of various fatty acids in the participants' blood.
The ARIC study team then measured the participants' cognitive functions three and nine years later, using tests designed to measure three key aspects of brain function:
- Delayed word recall (recent memory)
- Psycho-motor speed (turning thought in to quick, coordinated action)
- Verbal fluency
In the new study, scientists from the University of North Carolina, University of Minnesota, and Johns Hopkins analyzed the data collected by the AIRC researchers (Beydoun MA et al 2007).
After allowing for potential confounding factors, the joint research team determined that AIRC study participants who started the study period with the highest blood omega-3 levels enjoyed the smallest declines in declines in verbal fluency.
We should note that the new analysis did not detect any protection against overall
cognitive declines among the participants who had higher omega-3 levels.
As the analysts said, the results suggest that people like these participants—who had risk factors for heart disease also associated with greater dementia risk—may benefit from enriching their diet with omega-3s.
Expert commenters emphasize omega-3s' role in brain function
Two widely known researchers from the Oregon Health and Science University—William E. Connor, MD and Sonja Connor, MS, RD—penned an editorial in which they emphasized the importance of omega-3s in the development and performance of key parts of the brain.
As they said, “The brains of Alzheimer disease patients have a lower content of [omega-3] DHA in the grey matter of the frontal lobe and hippocampus than do the brains of persons without Alzheimer's disease.” (Connor WE, Connor SL 2007)
They went on to detail the benefits of omega-3s. (Note: cytokines and eicosanoids are messenger chemicals that influence inflammation.):
“The entrance of [omega-3] DHA into the brain could correct DHA deficiency in membrane phospholipids in the cerebral cortex in patients with Alzheimer's disease, and [omega-3] EPA would counter the pro-inflammatory action of [omega-6] arachidonic acid, which is a precursor of cytokine and pro-inflammatory eicosanoids that may be associated with greater cognitive decline.”
The married professorial pair, who co-authored The New American Diet in 1986, called for clinical trials of fish oil in older adults at risk of cognitive decline and Alzheimer's disease.
We urge our readers to write their congresspersons, to request for more federal funding of such studies.
- Beydoun MA, Kaufman JS, Satia JA, Rosamond W, Folsom AR. Plasma n-3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study. Am J Clin Nutr. 2007 Apr;85(4):1103-11.
- Chodosh J, Seeman TE, Keeler E, Sewall A, Hirsch SH, Guralnik JM, Reuben DB. Cognitive decline in high-functioning older persons is associated with an increased risk of hospitalization. J Am Geriatr Soc. 2004 Sep;52(9):1456-62.
- Connor WE, Connor SL. The importance of fish and docosahexaenoic acid in Alzheimer disease. Am J Clin Nutr. 2007 Apr;85(4):929-30.
- Morris MC, Evans DA, Bienias JL, Tangney CC, Bennett DA, Wilson RS, Aggarwal N, Schneider J. Consumption of fish and n-3 fatty acids and risk of incident Alzheimer disease. Arch Neurol. 2003 Jul;60(7):940-6.
- van Gelder BM, Tijhuis M, Kalmijn S, Kromhout D. Fish consumption, n-3 fatty acids, and subsequent 5-y cognitive decline in elderly men: the Zutphen Elderly Study. Am J Clin Nutr. 2007 Apr;85(4):1142-7.