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Previous studies
have suggested a link between Eskimos high intake of
omega-3 fats and their reduced risk of heart disease. Since
then, several other studies have strengthened the association
between the intake of omega-3 fats and the reduced risk of
heart disease.
In one study, 11,324
post--myocardial infarction patients were assigned to
receive either omega-3 fats eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA) or vitamin E, a combination of
the two, or neither for a 3.5-year period. No statistically
significant benefit was observed with vitamin E, however the
omega-3 fat group experienced a 20 percent decreased risk
of total mortality, a 30 percent lower risk of cardiovascular
mortality, and a 45 percent lower risk of sudden death.
Another recent
study involving the elderly (average age 78 years) extends
the benefits of omega-3 fats to people of this age group.
The study found a highly significant association between omega-3
fat concentrations and risk of fatal ischemic heart disease.
Also, there was a 48 percent lower risk of fatal coronary
heart disease (CHD) associated with plant-derived omega-3
fat ALA.
However, evidence
of benefit from ALA is less clear than evidence for other
omega-3 fats.
In two studies
that examined the effects of supplementation with ALA-rich
oils on CHD endpoints, no significant difference was found
between the groups who received increased doses of ALA and
those who did not.
ALA is the metabolic
precursor of EPA and DHA, however the amount of ALA converted
to EPA and DHA varies by study. For example, one study estimated
that 15 percent of ALA is converted to EPA and DHA, whereas
a separate study found an estimate of 0.2 percent. Further
research is needed to determine how much ALA is converted
to EPA and DHA in adults.
The increasing
evidence supporting the view that omega-3 fats reduce the
risk of death from CHD should not be ignored. The American
Heart Association recommends two fish meals (preferably fatty
fish) per week, however patients with CHD may need more. One
gram of EPA and DHA per day is recommended in this case. Researchers
note that it is difficult to obtain this amount from fish
alone.
American
Journal of Clinical Nutrition 2003, Harris 77 (2): 279
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