Back in 1997, an epidemiological study found that increased fish consumption was linked to a lower risk of Alzheimer’s Disease (1).
Then in 2005, a pre-clinical study showed that a diet rich in the poly-unsaturated omega-3 fatty acids slowed the progression of Alzheimer’s type brain pathology in an aged mouse model (2).
Three years later, a relatively small clinical trial found that small doses of omega 3’s led to some improvements in patients with mild cognitive impairment, although not with Alzheimer’s Disease (3).
All this boosted sales of fish oil supplements, and triggered another, larger trial headed by Joseph Quinn which was published in 2010 – with disappointing results. According to that study, daily supplements of docosahexaenoic acid (DHA), one of the two omega 3’s in fish oil, did not reduce cognitive decline in patients with mild-to-moderate Alzheimer’s disease (4,5).
According to the researchers, “The hypothesis that DHA slows the progression of mild to moderate Alzheimer disease was not supported, so there is no basis for recommending DHA supplementation.”
Here is a prime example of research using concepts and trial designs more suited to testing drugs than nutritional interventions.
The first self-evident truth is that Alzheimer’s Disease (AD) is clearly avoidable; many individuals reach ripe old ages without any signs of cognitive decline, and although genes are important, they have only been identified in less than 10% of cases of this disease.
The second self-evident truth is that the biochemical imbalances that have been identified in AD are far too many, and too complex, to be amenable to single, simple input solutions such as a single DHA supplement.
They are, however, amenable to diet, which contains thousands of different compounds, many of which are known to interact with brain chemistry.
The protective Mediterranean Diet
At Columbia University, Professor Nicholas Scarmeas has been studying the relationship between diet and AD for many years. He has published a series of papers that show, unequivocally, that the risk of developing this cruel disease is diminished by consuming a Mediterranean diet (6).
This is a diet that contains high levels of a range of bioactive compounds, including the anti-inflammatory flavonoids – which are also strongly linked to a reduced risk of AD (7), and have plausible mechanisms of action (8, 9).
The current anti-AD drugs are of limited use, and have a range of adverse effects. If you want to protect yourself or a loved one against AD, the logical way forward is not drugs, or pharma-style single compound supplements, but by dietary improvement supported by a comprehensive, broad spectrum micro- and phyto-nutritional support programme.
The programme should contain omega 3’s, which after all play a key role in neuronal defence mechanisms (10); but they must also contain flavonoids and a wide range of anti-oxidants. This is critical; omega 3 supplements taken alone, without anti-oxidants, are oxidised in the body producing toxic and pro-inflammatory lipid oxidation products which shorten life span in pre-clinical models (11); and exacerbate AD (12)!
No wonder the big Quinn trial failed. When the researchers must have known, from the National Health and Nutrition Examination Survey (NHANES), that their patients were suffering from dysnutrition and poor anti-oxidant status, why did these so-called experts design such a bad trial?
Conclusion: Mono-supplementation with single nutrients is not going to lead to better health. Only a comprehensive combination of natural compounds, reproducing the elements of an ideal Mediterranean-style diet, can be expected to support long-term health and longevity.
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1. Grant WB. Dietary links to Alzheimer’s disease. Alzheimer Dis Rev 1997;2:42–55.
2. Lim GP, Calon F, Morihara T, Yang F, Teter B, Ubeda O, Salem N Jr, Frautschy SA, Cole GM. A diet enriched with the omega-3 fatty acid docosahexaenoic acid reduces amyloid burden in an aged Alzheimer mouse model. J Neurosci. 2005 Mar 23;25(12):3032-40
3. Chiu CC, Su KP, Cheng TC, Liu HC, Chang CJ, Dewey ME, Stewart R, Huang SY. The effects of omega-3 fatty acids monotherapy in Alzheimer’s disease and mild cognitive impairment: a preliminary randomized double-blind placebo-controlled study. Prog Neuropsychopharmacol Biol Psychiatry. 2008 Aug 1;32(6):1538-44
4. Quinn JF, Raman R, Thomas RGH, Yurko-Mauro K, et al. Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease: A Randomized Trial. JAMA 2010, 304 (17), 1903-1911
5. Yaffe K. Treatment of Alzheimer Disease and Prognosis of Dementia. JAMA 2010, 304 (17), 1952-1953: editorial
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8. Fernandez JW, Rezai-Zadeh K, Obregon D, Tan J. EGCG functions through estrogen receptor-mediated activation of ADAM10 in the promotion of non-amyloidogenic processing of APP. FEBS Lett. 2010 Oct 8;584(19):4259-67
9. Jomova K, Vondrakova D, Lawson M, Valko M. Metals, oxidative stress and neurodegenerative disorders. Mol Cell Biochem. 2010 Dec;345(1-2):91-104
10. Palacios-Pelaez R, Lukiw WJ, Bazan NG. Omega-3 essential fatty acids modulate initiation and progression of neurodegenerative disease. Mol Neurobiol. 2010 Jun;41(2-3):367-74
11. Tsuduki T, Honma T, Nakagawa K, Ikeda I, Miyazawa T. Long-term intake of fish oil increases oxidative stress and decreases lifespan in senescence-accelerated mice. Nutrition. 2010 Jul 10. [Epub ahead of print]
12. Liu L, Komatsu H, Murray IV, Axelsen PH. Promotion of amyloid beta protein misfolding and fibrillogenesis by a lipid oxidation product. J Mol Biol. 2008 Apr 4;377(4):1236-50