Ask the Doctors - I take fish oil every day, but does it help?

Dr. Robert Ashley, MD

Dear Doctors: I've been taking fish oil capsules daily over the last 5 years. Is there any benefit in doing this?

Small studies have shown that fish oil may be linked to a slight reduction in the formation of plaque in the arteries that supply the heart, but evidence of its ability to reduce the rates of heart attack hasn’t been as robust or as statistically significant.

One fish oil finding that was indeed statistically significant was from a large study published in the Journal of the American Medical Association in 2006. That study linked fish oil intake of 250 milligrams per day to a 36% reduction in rates of sudden cardiac death. That amount – 250 milligrams of fish oil -- equals 1-2 servings of fish per week.

One other property that fish oil may have is an ability to reduce electrical excitability of the heart. That reduced excitability may decrease the heart's chances of going into an abnormal rhythm, which can lead to death. Furthermore, among people who have had a heart attack, one gram of fish oil per day has been linked to a significant decrease in death rates. The benefits were seen as early as four months after the heart attack and even as late as 36 months after a heart attack. Again, this appears to be related to fish oil's potential protective effect against abnormal heart rhythms after a heart attack.

Fish oil hasn’t been shown to decrease the chance of a stroke. Nor has it been shown to decrease the risk or incidence of cancer. In fact, some studies have shown a correlation between fish oil and prostate cancer, but other studies have failed to support that connection.

In summary, fish oil does appear to decrease the chance of sudden cardiac death, but you don't need to take capsules to see this benefit. Eating fish twice a week can do that.

Before you turn to eating tuna fish from a can, keep in mind that tuna has much less omega 3 fatty acids than Atlantic salmon, mackerel, or herring. If you don't care for fish, taking 1 gram of a fish oil supplement twice a week will likely yield a benefit. If you’ve had a heart attack, consider taking 1 gram of fish oil a day.

Robert Ashley, MD, is an internist and assistant professor of medicine at the University of California, Los Angeles.

Ask the Doctors is a syndicated column first published by UExpress syndicate.