Alzheimers: Omega-3 Fish Oil Protects The Brain

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There is hope for Alzheimer's patients and those who are at risk. A new study by Louisiana State University scientists shows that docosahexaenoic acid (DHA), an omega-3 fatty acid found in coldwater fish such as mackerel, sardines and salmon, reduces levels of a protein known to cause damaging plaques in the brains of Alzheimer's patients.

With a fairly simple type of intervention - a change of diet or just adding some of the fish oil readily available in your local health food store - we now have a valid preventive tool against a disease that has been on the rise, resisting pharmaceutical intervention.

See Scientists Discover How Fish Oil Protects the Brain

As the article mentions, much of the research into omega-3 fatty acids is centered on the prevention of heart disease, one of the major killer diseases in the developed countries. Perhaps a general increase of the proper fatty acids and dietary antioxidants in what we eat could go a long way towards reducing the incidence of not only Alzheimer's but also cardiovascular disease. The damaging rush to control cholesterol levels by the way of lipid-lowering statin drugs (see articles on the inherent dangers of lipitor here and here) could easily come to an early end if these connections were widely recognized by health professionals.

The following somewhat technical overview by Beldeu Singh suggests as much.

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Date: Thu, 29 Sep 2005
From: beldeu singh
Subject: WHY OMEGA-3 FISH OIL PROTECTS YOUR HEART AND BRAIN

The interest in omega-3 fish oil comes from studies in omega-3 polyunsaturated fatty acids which have been observed to help reduce the risk of heart disease. Several studies have indicated that increasing omega-3 essential fatty acids in the diet and reducing saturated fats and omega-6 polyunsaturated fatty acids can significantly reduce the risk of mortality from cardiovascular disease and that includes patients with previous cardiac events. There is strong experimental evidence that omega 3 fatty acids may prevent sudden cardiac death in humans.

There are studies that continue to assess the role of omega-3 fatty acids in cardiovascular disease. One of the most recent fish oil study reported in the Annals of Internal Medicine concluded that omega-3 fatty acids can slow the course of atherosclerosis and may reduce the risk of further heart disease. The Diet and Reinfarction Trial (DART) showed a 29% reduction in overall mortality rates in survivors of a first myocardial infarction who ingested as little as two fish meals per week for two years.

Some experiments suggest fatty acids in fish oils have a potent antiarrythmic effects. In the laboratory, these omega-3 fatty acids prevent myocardial cells from losing calcium, which is essential for normal contractility.

The importance of eating fish may be that it acts at such an early stage to inhibit plaque formation in the process of atherosclerosis. The impact of omega 3 fatty acids on blood cholesterol level is due to the saturated fat reduction, not from the specific effect of the fish oils. Marine omega-3 fatty acids have been shown to effectively lower blood triglyceride levels. The proposed mechanism of action is related to the production of potent eicosanoids.

"Rat diets high in fish oil have been shown to be protective against ischemia-induced fatal ventricular arrhythmias. Increasing evidence suggests that this may also apply to humans. To confirm the evidence in animals, researchers tested a concentrate of the free fish-oil fatty acids and found them to be antiarrhythmic. In this study, the researchers tested
the pure free fatty acids of the 2 major dietary -3 polyunsaturated fatty acids in fish oil: cis-5,8,11,14,17-eicosapentaenoic acid (C20:5-3) and cis- 4,7,10,13,16,19-docosahexaenoic acid (C22:6-3), and the parent omega-3 fatty acid in some vegetable oils, cis-9,12,15--linolenic acid (C18:3-3), administered intravenously on albumin or a phospholipid emulsion.

The tests were performed in a dog model of cardiac sudden death. Dogs were prepared with a large anterior wall myocardial infarction produced surgically and an inflatable cuff placed around the left circumflex coronary artery. With the dogs running on a treadmill 1 month after the surgery, occlusion of the left circumflex artery regularly produced ventricular fibrillation in the control tests done 1 week before and after the test, with the -3 fatty acids administered intravenously as their pure free fatty acid. With infusion of the eicosapentaenoic acid, 5 of 7 dogs were protected from fatal ventricular arrhythmias (P smaller than 0.02). With docosahexaenoic acid, 6 of 8 dogs were protected, and with -linolenic acid, 6 of 8 dogs were also protected (P smaller than 0.004 for each). The before and after control studies performed on the same animal all resulted in fatal ventricular arrhythmias, from which they were defibrillated" (George et al, (Circulation. 1999;99:2452-2457: American Heart Association, Inc.)

The research was conducted by researchers at the Department of Physiology, The Ohio State University, Columbus, Ohio (G.E.B.) and Departments of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Mass (J.X.K., A.L.). The results from these experiments indicate that purified -3 fatty acids can prevent ischemia-induced ventricular fibrillation in this dog model of sudden cardiac death.

One key study on diet found an association between dietary intake of omega-3 fatty acids from fish and a reduced risk for sudden cardiac death. Eating as little as one to two fish servings a week may reduce the risk of occurrence of cardiac arrest. The first clinical cardiovascular trial was reported in 1989 by Burr and associates. They performed a randomized controlled trial with a factorial design in 2033 men to determine whether dietary advice on fat, fish, or fiber is beneficial in the secondary prevention of myocardial infarction (MI). No benefits accrued from the fat and fiber advice. At the end of 2 years, however, there was a 29% reduction in mortality in the 1015 men who had received advice to eat oily fish, at least 200- to 400-g portions twice weekly, compared with the 1018 men who had not received such advice. (Burr et al, Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial (DART). Lancet 1989; 334: 757-61.) Such anthropological studies often provide important information for further research.

Protective effects not linked to levels of total cholesterol

Fortunately there were follow-up studies, and the follow-up findings of the Lyon Diet Heart Study were reported. This study showed a dramatic 70% reduction in all-cause mortality due to reduction in CHD mortality. The reduction in risk was not associated with differences in total cholesterol (De Lorgeril M et al, Mediterranean alpha-linolenic acid-rich diet in secondary prevention of coronary heart disease. Lancet 1994; 143: 1454-1459.)

This finding is of critical importance as it shows that the cardioprotective effect of a Mediterranean style diet is not linked to total cholesterol.

A subsequent study examined traditional risk factors and the rate of cardiovascular complications after myocardial infarction. This classic secondary prevention study that showed a significant reduction (29%) in all-cause mortality over a two-year period in subjects eating as little as two to three fish portions per week (De Lorgeril M et al, Final report of the Lyon Diet Heart Study. Circulation 1999;99:779-785.)

More recently, the data in the Physicians‚ Health Study have been examined to test whether n-3 fatty acid consumption would reduce the risk of sudden death in subjects without a history of preexisting cardiovascular disease. A prospective, nested, case-control analysis among apparently healthy men who were followed up for 17 years in the Physicians‚ Health Study was conducted retrospectively (Albert CM, et al. Blood levels of long-chain n-3 fatty acids and the risk of sudden death. N Engl J Med. 2002; 346: 1113-1118). Ninety-four men were identified in whom sudden cardiac death occurred as the first manifestation of cardiovascular disease. The fatty acid composition of blood, which had been collected at baseline on all subjects, was determined. Baseline blood levels of long-chain n-3 fatty acids were very significantly inversely related to the risk of sudden death. Compared with the men whose blood levels of the n-3 fish oil fatty acids were in the lowest quartile, the relative risk of sudden death was significantly lower among men in the third quartile (relative risk ratio, 0.28) and in the fourth quartile (0.19). The 72% and 81% relative risk reductions are the largest beneficial cardiac effects of the n-3 PUFAs reported thus far in humans.

The alpha-linolenic acid-rich Mediterranean diet which has been shown to have cardioprotective effects indicates several important nutritional implications of the Lyon Diet Heart Study. Dr. Leaf stresses the importance of nutrition and its key role in reducing heart disease risk (Leaf A. Dietary prevention of coronary heart disease. The Lyon Diet Heart Study. Circulation 1999; 99:733-735.)

The absence of a link between the cardioprotective effect of omega-3 oil and its ability to reduce the risk of sudden death in subjects without a history of preexisting cardiovascular disease have a very special significance in understanding the role of omega-3 oil in heart health.

Fatal cardiac arrythmias

The clinical importance of omega-3 studies lie in the fact that 50-60% of deaths in the heart disease cases are sudden cardiac deaths - i.e. deaths that occur within one hour of the symptoms of a heart attack. These deaths are attributed to sustained ventricular arrhythmias or irregular heart beat. Animal studies experiments had shown that fatty acids from n-3 fish oils are stored in cell membranes of heart cells suggesting their peculiar role in preventing sudden heart death caused by fatal arrhythmias. But what initiates fatal arrhythmia? The answer to this lies in biochemistry and physiology. So, Leaf and other researchers cultured neonatal heart cells from rats. Under the microscope, these cells clumped together which as a clump of heart cells beat spontaneously and rhythmically just like the heart as an organ. Toxic agents known to produce fatal arrhythmias in humans were added to the medium bathing the cultured cells, and the effects of adding the n-3 fatty acids were observed. Increased extracellular Ca2+, the cardiac glycoside ouabain, isoproterenol, lysophosphatidylcholine and acylcarnitine, thromboxane, and even the Ca2+ ionophore A23187 were tested. All of these agents induced tachyarrhythmias in the isolated myocytes (Leaf A Circulation. 2003;107:2646, 2003 American Heart Association, Inc.)

Of particular interest are the effects of elevated perfusate Ca2+ and ouabain on the myoctes. Both agents induced rapid contractions, contr