More evidence that eating fish can help prevent against Alzheimer's

Posted on February 25, 2016 by Susie Allport | 0 Comments

Fish Found to Protect People at Risk for Alzheimer's
No link found between dementia symptoms and higher brain levels of mercury
2/5/2016By Craig weatherby
Print Share E-Mail Google+ Twitter Facebook
ImageThe findings of a unique new study are fishy … in a good way.
Many studies suggest that eating seafood helps protect against dementia.
On the other hand, seafood is a source of mercury, which can damage the brain, indirectly.
Mercury binds to selenium … an essential part of internal antioxidants that protect the brain from free radicals.
This explains why people who consume more mercury than selenium can suffer brain damage that harms thinking and memory (so-called cognitive impairment).
And it likely explains why adults and children who eat far more fish than most Americans do very well on developmental and academic tests.
Now, a study from Chicago’s Rush University Medical Center – published in theJournal of the American Medical Association – reinforces the brain benefits of seafood.
Brain study is first of its kind
The new study is the first to compare both seafood consumption and brain levels of mercury to the risk for Alzheimer’s disease and the presence of its physical signs in the brain (Morris MC et al. 2015).
The researchers recruited 544 older people who were free of dementia at the outset of the study, and followed them for an average of 4.5 years.
Participants' seafood intake was measured by multiple questionnaires completed in the years before their death.
The amounts of seafood reported by the participants ranged from low to moderate, and consisted mostly of the top 10 species consumed in the U.S. (including salmon and tuna), which have low to moderate levels of mercury.
The researchers performed brain autopsies on 286 people who died during the course of the study.
They measured the levels of mercury and selenium, and for abnormalities characteristic of Alzheimer’s disease.
As study leader Martha Clare Morris, ScD, said, "Since mercury is a known neurotoxin, we wanted to determine whether brain mercury levels are correlated with brain neuropathologies.”
Fish-rich diets linked to lower dementia risk
The results of the brain autopsies fit with previous studies linking seafood-rich diets to reduced dementia risk.
The results of the autopsies linked higher seafood consumption to lower risk for Alzheimer's disease ... despite increased mercury levels.
The autopsies also linked higher seafood intakes to lower risk for two signs associated with Alzheimer’s disease: amyloid "plaque” and brain-cell "tangles”.
It's important to note that the relatively large number of brains analyzed lowered the likelihood that the findings were due to chance.
Few participants took fish oil routinely, so the researchers couldn’t draw any clear conclusions about its possible value for preventing dementia.
Benefits limited to high-risk participants
The study results only found brain benefits in certain people.
Fewer signs of Alzheimer's were seen only in the brains of those who met two criteria:
  • Ate more seafood than most of the study participants.
  • Had a specific variation in an Alzheimer's related gene called APOE. 
That gene variation – called APOE4 – raises the risk of Alzheimer's disease very substantially.
What do the results mean?
Diets rich in seafood don't guarantee you won't get Alzheimer's or other, less common forms of dementia.
But there's now ample evidence that it's smart to eat plenty of seafood, and take omega-3 fish oil as insurance.
Enjoying seafood two or more times a week may delay the onset of dementia, and/or reduce the severity of its symptoms.
And the available evidence suggests that you can do even better by getting plenty of exercise and filling your plate with antioxidant-rich plant foods.
Your best choices are colorful fruits and vegetables, extra virgin olive oil, green tea, extra-dark chocolate, and natural (non-alkalized) cocoa.
Sources
  • 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.
  • Björnberg KA, Vahter M, Grawé KP, Berglund M. Methyl mercury exposure in Swedish women with high fish consumption. Sci Total Environ. 2005 Apr 1;341(1-3):45-52.
  • Connor WE, Connor SL. The importance of fish and docosahexaenoic acid in Alzheimer disease. Am J Clin Nutr. 2007 Apr;85(4):929-30. 
  • Dangour AD, Allen E, Elbourne D, Fasey N, Fletcher AE, Hardy P, Holder GE, Knight R, Letley L, Richards M, Uauy R. Effect of 2-y n-3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial. Am J Clin Nutr. 2010 Jun;91(6):1725-32. doi: 10.3945/ajcn.2009.29121. Epub 2010 Apr 21.
  • Karimi R, Silbernagel S, Fisher NS, Meliker JR. Elevated blood Hg at recommended seafood consumption rates in adult seafood consumers. Int J Hyg Environ Health. 2014 Sep;217(7):758-64. doi: 10.1016/j.ijheh.2014.03.007. Epub 2014 Apr 6.
  • Morris MC, Brockman J, Schneider JA, Wang Y, Bennett DA, Tangney CC, van de Rest O. Association of Seafood Consumption, Brain Mercury Level, and APOE ε4 Status With Brain Neuropathology in Older Adults. JAMA. 2016 Feb 2;315(5):489-97. doi: 10.1001/jama.2015.19451.
  • 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.
  • Morris MC, Evans DA, Tangney CC, Bienias JL, Wilson RS. Fish consumption and cognitive decline with age in a large community study. Arch Neurol. 2005 Dec;62(12):1849-53. Epub 2005 Oct 10.
  • Nielsen SJ, Aoki Y, Kit BK, Ogden CL. More than half of US youth consume seafood and most have blood mercury concentrations below the EPA reference level, 2009-2012. J Nutr. 2015 Feb;145(2):322-7. doi: 10.3945/jn.114.203786. Epub 2014 Dec 17.
  • Nielsen SJ, Kit BK, Aoki Y, Ogden CL. Seafood consumption and blood mercury concentrations in adults aged ≥20 y, 2007-2010. Am J Clin Nutr. 2014 May;99(5):1066-70. doi: 10.3945/ajcn.113.077081. Epub 2014 Feb 12.
  • Schaefer EJ, Bongard V, Beiser AS, Lamon-Fava S, Robins SJ, Au R, Tucker KL, Kyle DJ, Wilson PW, Wolf PA. Plasma phosphatidylcholine docosahexaenoic Acid content and risk of dementia and Alzheimer disease: the framingham heart study. Arch Neurol. 2006 Nov;63(11):1545-50.
  • 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.
Special Offers • Recipes
Nutrition & Eco News
RECENT ARTICLES


Hippocrates on Flaxseed

Some more places to purchase Susie's Smart Breakfast Cookies...

Leave a Reply

Comments have to be approved before showing up.

Recent Articles