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Benefits of Omega-3 Fatty Acids American
Family Physician, Feb 1, 2005
An analysis of 10 randomized controlled trials (RCTs) and
nine other studies addressed the effects of omega-3 fatty
acids on respiratory outcomes. The AHRQ could not conclude
whether omega-3 fatty acids are an efficacious adjuvant or
monotherapy in improving respiratory outcomes in adults or
children.
Six studies were analyzed to determine the role of
omega-3 fatty acids in primary prevention of asthma. Dietary
fish consumption appears to serve as primary prevention for
asthma in pediatric populations. However, asthma prevalence
and fish intake were significantly and positively related in
studies that included Asian adolescents. Another study found
no association between adult asthma onset and dietary fish
intake.
In terms of cardiovascular benefits, a number of studies
show that fish consumption and fish and [alpha] linolenic
acid (ALA) supplementation reduces all-cause mortality and
various cardiovascular outcomes, although the evidence is
strongest for fish and fish oil. The effects on specific
outcomes (especially myocardial infarction [MI] and stroke)
are uncertain, and the optimal quantity and type of omega-3
fatty acid, and the optimal ratio of omega-3 to omega-6
fatty acid remain unknown. The most significant benefit may
be in reducing sudden cardiac death. Four of six RCTs found
a benefit, one found no benefit, and one found harm,
although all six were thought to be poorly designed. Adverse
events from fish oil and ALA supplementation appear to be
minor.
Overall, strong evidence shows that fish oils have a
strong, dose-dependent beneficial effect on triglyceride
levels. There also is evidence of possible small beneficial
effects on blood pressure and coronary artery restenosis
after angioplasty, exercise capacity in patients with
coronary atherosclerosis, and heart rate variability,
particularly in patients with recent MI. Omega-3 fatty acids
do not appear to affect total cholesterol, high-density
lipoprotein cholesterol, low-density lipoprotein
cholesterol, fasting blood sugar, or glycosylated hemoglobin
levels, and they had no effect on plasma insulin levels and
insulin resistance in patients with type 2 diabetes. |
