Another benefit of fish oil...
One benefit of fish oil supplementation is that it helps a condition
related to asthma called exercise-induced bronchoconstriction in
highly trained athletes.
Exercise-induced bronchoconstriction (known more simply as EIB)
is a condition characterized by a temporary narrowing of the airway
passages in the lungs during and after exercise.
Unlike typical asthma, EIB does not respond well to medications
used to prevent asthma attacks. The cause of EIB is not completely
understood. It may be linked to substances such as histamine and
leukotrienes that cause inflammation in the lungs.
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are
omega-3 fatty acids found in fish oil. When the balance between
omega-3 and omega-6 fatty acids in the body is disturbed, inflammation
can result. One of the benefits of fish oil is that the omega-3
fatty acids help to keep inflammation in check.
Participants were received either 3.2 grams of EPA and 2.2 grams
of DHA from fish oil per day, or a placebo for three weeks. A placebo
is a "fake" supplement used to reduce the influence of
faith and belief in a treatment on the results of a study.
After a two-week period, the two groups switched treatments and
remained on the new treatment for another three weeks.
Lung function was significantly better, and levels of inflammatory
markers in the blood and urine were lower during treatment with
omega-3 fatty acids than during the placebo.
So, should you take a supplement or simply eat more fish?
Harvard researchers think that consuming fish
oil
supplements may be safer than eating fish.
They analyzed five brands of fish oil for their
content
of polychlorinated biphenyls (PCBs), and other organochlorines
(OCs)
such as DDT.
PCBs are industrial byproducts that were banned in the late seventies,
but are still found in products made prior to the ban and continue
to
linger in the environment. PCBs have reproductive, skin, glandular,
liver, developmental and immunologic effects and are known
carcinogens.
The researchers found that the levels of PCBs and organochlorines
were
below the detectable limit in the five brands tested. They note
that
fish oil contains at least 5 times less PCBs than the FDA limits.
If
fish from the Great Lakes was consumed at the optimal recommended
amount of 400 grams of fish per week, one would be consuming
at least
70 times more PCBs and 120 times more organochloride pesticides
than
would be consumed with a customary dose of 1.5 grams fish oil
per day
for one week.
Their data suggests that even large
amounts
of
fish oil can be consumed without risk of toxicity, and that fish
oil supplements may be preferable to fish consumption as a
source of long-chain omega-3 fatty acids.
Reference
Melanson SF, Lewandrowski EL, Flood JG, Lewandrowski KB. (2005).
Measurement of organochlorines in commercial over-the-counter
fish oil preparations. Archives
of Pathology and Laboratory Medicine, 129, 74-77
Mickleborough TD, Murray RL, Ionescu AA, Lindley MR. (2003). Fish
oil supplementation reduces severity of exercise-induced bronchoconstriction
in elite athletes. American
Journal of Respiratory and Critical Care Medicine, 168,
1181-1189
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