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Fish and omega 3's: sometimes more is more ...
By now most of us are aware of the benefit of including omega-3 fatty acid-rich fish in our diets once or twice per week to help protect against cardiovascular and other disease. Now the findings of a study published in the January 17, 2006 issue of Circulation, the journal of the American Heart Association, show that consuming more fish and, consequently, more omega-3s, leads to an even greater reduction in the risk of coronary heart disease.
Researchers in Japan followed 41,578 men and women aged 40 to 59 who did not have cardiovascular disease or cancer upon enrollment, from 1990-1992 to 2001. Food frequency questionnaires completed at the beginning of the study and in 1995 provided information on weekly fish intake, which was analyzed for omega-3 content.
Over the follow-up period there were 196 nonfatal and 62 fatal coronary events. When individuals whose fish consumption was in the top one-fifth of participants at eight times per week were compared with those whose intake was in the lowest fifth at once per week, they were found to have a 37 percent lower risk of incident coronary heart disease and a 56 percent lower risk of heart attack. The risk reduction was mainly found for nonfatal coronary events.
When the effect of omega-3 fatty acid intake on cardiovascular risk was analyzed, coronary heart disease risk was lowered by 42 percent among those whose intake was the highest at 2.1 grams per day or more compared to those whose intake was the lowest at 300 milligrams per day. There was a 65 percent reduction in the risk of heart attack among those whose intake was in the top fifth compared to those whose intake was lowest. Nonfatal coronary events were similarly reduced.
In their discussion of the protective mechanism of omega-3 fatty acids in atherosclerosis, the authors explain that they reduce platelet aggregation, as well as decrease the production of leukotrienes which reduces the proliferation of endothelial cells.
“High consumption of fish was associated with reduced risk of coronary heart disease, more specifically, myocardial infarction and nonfatal coronary heart disease, compared with a modest fish consumption,” the authors conclude. “Our results suggest that a high fish intake may add a further beneficial effect for the prevention of coronary heart disease among middle-aged persons.”
Fish oil protects against Alzheimer's disease
High levels of the omega-3 fatty acid docosahexaenoic acid (DHA) are found in the more active areas of the brain including the cerebral cortex, mitochondria, synaptosomes, and synaptic vesicles. At least one epidemiologic study has shown that patients with Alzheimer's disease (AD) have significantly lower levels of omega-3 fatty acids in their plasma phospholipids than do age-matched controls. Researchers at the Rush-Presbyterian-St. Luke's Medical Center now report that older people can reduce their risk of developing AD by increasing their intake of fish and fish oil (DHA). Their study included 815 men and women over the age of 65 years who had showed no sign of AD during a thorough baseline examination. About 2 years after the examination all participants completed a 154-item food frequency questionnaire and provided information about their current use of supplements. After another 2 years all participants were again subjected to a thorough, structured neurologic clinical evaluation to establish the presence or absence of AD. A total of 131 study participants were found to have developed AD over the 3.9-year follow-up period.
The researchers found that participants who consumed fish just once a week had a 60% lower risk of developing AD than did those who rarely or never ate fish. They also observed that participants whose daily intake of DHA was about 100 mg/day had an incidence of AD which was 70% lower than those with an intake of 30 mg/day or less.
Eicosapentaenoic acid (EPA), another component of fish oil, showed no appreciable effect; however, the maximum intake was only 30 mg/day. A high total intake of omega-3 fatty acids was also strongly correlated with a reduced risk for AD. Participants with an intake of 1.6 – 4.1 grams/day had a 70% lower risk than those with an intake below 1.05 grams/day. Alpha-linolenic acid (flaxseed oil) intake was not associated with AD risk except in the case of people with the APOE-epsilon 4 allele where a high intake was strongly protective. The researchers conclude that an increased intake of fish or omega-3 fatty acids, especially DHA, can substantially reduce the risk of developing Alzheimer's disease.Morris, MC, et al. Consumption of fish and n-3 fatty acids and risk of incident of Alzheimer's disease. Archives of Neurology, Vol. 60, July 2003, pp. 940-46Friedland, RP. Fish consumption and the risk of Alzheimer disease. Archives of Neurology, Vol. 60, July 2003, pp. 940-46
Comment: High doses of fish oils should always be accompanied by vitamins E and C in order to prevent oxidation of the oil.
NSI Omega 3 Fatty Acids
Christopher Wiechert's Healthblogger is for educational or informational purposes only, and is not intended to diagnose or provide treatment for any condition. If you have any concerns about your own health, you should always consult with a healthcare professional. If you decide to use this information on your own, it's your constitutional right, but I assume no responsibility.
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