Fish Oil Continues to Show Benefits in Treating a Variety of Ailments
(HealthDay News) -- More and more frequently, the value of eating fish is being tied directly to protecting your heart and lungs.
Here are two recent examples: A gene that can increase the risk of heart attack and stroke is combated by polyunsaturated fatty acids found in fish like salmon.
And another study found that fish oil capsules actually reduced breathing problems in “elite athletes,” those who constantly trained hard and stayed in shape.
The results concerning the athletes were published in the American Journal of Respiratory and Critical Care Medicine. Scientists found that three weeks of fish oil capsules markedly reduced the severity of exercise-induced bronchoconstriction (EIB) in elite athletes. Brochoconstriction is another way of saying that it’s difficult to breathe after heavy exercise.
The study involving the gene that could induce a heart attack was aimed at reducing blood levels of one sort of fatty molecule, low-density cholesterol. One way, the researchers said, was to eat certain fish.
And the idea is to avoid foods containing n-6 polyunsaturated fatty acids, a class of fats that set off the inflammatory reaction. However, a different class of polyunsaturated fatty acids -- designated n-3, which are found in fish -- suppresses the inflammatory response.
Inflammation has been big news in cardiovascular research. Study after study has shown that high blood levels of C-reactive protein, a marker of inflammation, are associated with increased risk of artery damage. But until now, no one has known why the inflammatory attack occurs.
"This is the first example of how a gene that causes inflammation is involved in artery blockage," says Hooman Allayee, assistant professor of preventive medicine at UCLA’s Keck School of Medicine in Los Angeles and a member of the Institute for Genetic Medicine. Allayee was leader of the team reporting the finding in the Jan. 1, 2004 issue of the New England Journal of Medicine.
He and his colleagues have found a fairly common form of the gene for 5-lipoxygenase, a molecule involved in the body's defense against injury, can be activated by fatty acids in the diet to attack the arteries.
Inflammation is a basic defense mechanism, but it can often go wrong, causing diseases such as rheumatoid arthritis and asthma, explains study co-author James H. Dwyer, professor of preventive medicine at the University of Southern California. In this case, the gene causes the attack to be aimed at the arteries, he says.
A study of 470 healthy Los Angeles residents found that about 6 percent of them carry the potentially dangerous form of the gene, Dwyer says. Detailed studies shown abnormal thickening of artery walls, a warning sign of cardiovascular disease, in the people with that form of the gene.
People who carry the dangerous version of the gene should avoid foods containing two n-6 polyunsaturated fats, arachidonic acid and linoleic acid, all of which stimulate the inflammatory activity, Dwyer says. Organ meats -- liver, heart, giblets -- should be avoided because they have high levels of arachidonic acid. Vegetable oils from corn and soybeans should be avoided because they are rich in linoleic acid, he says. Olive oil is preferable because it has a lot of n-3 polyunsaturated fatty acids, which prevent inflammation.
The gene "is more prevalent in people of non-European ancestry, such as blacks and Asians," Dwyer says. "About 10 to 20 percent of them have this form of the gene. Specific dietary and pharmaceutical intervention should be effective in this group."
The variant form of the gene seems to make a normal process of repairing injury to an artery become dangerous, Dwyer says. "If our findings are confirmed to show that people carrying this genotype are at increased risk, it won't be long until we have a routine clinical test to detect it," he says.
But these are "early days," Dwyer adds. "We need a lot more practical experience."
Insofar as the athlete breathing research was concerned, researchers examined 10 athletes with EIB and 10 without EIB (10 triathletes, five cross-country runners, and five track runners). They received either fish oil capsules containing omega-3 polyunsaturated fatty acids (PUFA) or placebo capsules filled with olive oil daily for three weeks.
When lung function tests were done 15 minutes after exercise, the athletes taking the fish oil capsules showed a 3 percent decrease in lung function compared with a 14.5 percent decrease for those on the placebo.
On the Web
You can learn what is known about the role of inflammation in heart disease from the American Heart Association.
Author: Ed Edelson, HealthDay Reporter
SOURCES: Hooman Allayee, Ph.D, assistant professor of preventive medicine, Keck School of Medicine, University of California at Los Angeles and member, the Institute for Genetic Medicine, University of California, Los Angeles; James H. Dwyer, Ph.D., professor, preventive medicine, Keck School of Medicine, University of Southern California, Los Angeles; American Journal of Respiratory and Critical Care Medicine, November, 2003; Jan. 1, 2004, New England Journal of Medicine
Publication date: October 1, 2005
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