Study Finds No Benefit from Fish Oil Pills

Fish oil pills don't reduce the risk of heart attack and stroke in people at high risk of heart disease, a new study suggests. Earlier studies concluded that eating fatty fish, such as salmon and tuna, could lower risk in people with heart failure or a previous heart attack. The new study focused on about 12,500 people who never had a heart attack or stroke. But they had high blood pressure, a family history of heart disease or several other factors that increased their risk. They already were taking medicines to address those risks. People were randomly divided into 2 groups. One group took a daily capsule containing omega-3 fatty acids found in fish. The other group took placebo pills that contained olive oil. In the next 5 years, about 12% of each group died or spent time in a hospital because of a heart attack, stroke or other heart-related problem. People who got the real fish oil did not have better results. The New England Journal of Medicine published the study. The Associated Press wrote about it May 9.

By Howard LeWine, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Fish oil has been flying high as a health-boosting supplement. It has garnered a reputation as an easy way to protect the heart, improve brain function and lengthen life.

Such claims are one reason that Americans spend more than $1 billion a year on over-the-counter fish oil. Food companies also are adding it to milk, yogurt, cereal, chocolate, cookies, juice and many other foods.

Fish oil is loaded with omega-3 (or n-3) fatty acids. There are three main types:

• Eicosapentaenoic acid (EPA)
• Docosahexaenoic acid (DHA)
• Alpha-linolenic acid (ALA)

EPA and DHA are found mainly in fish. For that reason, they are sometimes called marine omega-3s. ALA is found in plant-based foods, such as flaxseed, walnuts, and canola and soybean oils.

It's true that healthy people tend to have high levels of EPA and DHA in their blood. People with heart failure, stroke and heart attack often have lower levels of these omega-3 fatty acids. However, this does not necessarily mean that taking fish oil pills will prevent heart disease.

In fact, there is now good evidence that you do not decrease your chance of heart attack, stroke or death by taking fish oil pills. Based on the results of a new study, even people at high risk of heart attack, stroke or premature death showed no benefit. Study results appear in today's New England Journal of Medicine.

All of the people enrolled in the study had known blood vessel disease or had multiple factors that put them at high risk. They had at least four of the following risk factors, or they had diabetes and at least one of these factors:

• Age 65 or older
• Male sex
• High blood pressure
• High cholesterol
• Current smoker
• Obesity
• A family history of coronary artery disease at a younger age (father or brother younger than 55, mother or sister younger than 65)

People in the study were randomly assigned to take capsules containing either olive oil or omega-3 fatty acids. Results for the two groups were the same. The omega-3 capsules did not prevent death or hospital stays for heart attack or stroke.

Side effects were also measured during the study. Minor side effects were similar in both groups. People reported no major side effects.

What Changes Can I Make Now?

To help prevent heart disease and lower your risk of heart attack and stroke, don't rely on omega-3 fatty acid pills. But do keep eating fish, especially fatty fish that are rich in omega-3 fatty acids. Examples of fatty fish include salmon, sardines, mackerel, char and halibut.

Why the fish but not fish oil pills? Multiple well-done studies have shown that fish eaters have lower rates of heart disease and stroke. True, that doesn't prove that the fish directly causes the lower risk. But fish is one of the healthiest sources of protein.

Also, stick to the proven ways to lower your chance of heart attack and stroke:

• Quit smoking.
• Exercise more.
• Eat smaller portions of food and decrease saturated fat.
• Keep your blood pressure in the normal range, with medicines if needed.
• Know your LDL cholesterol level. Lower it with a statin or other medicine if needed.
• Talk with your doctor about whether you should take a baby aspirin.

You might still decide to take fish oil pills or another type of omega-3 supplement. At low to moderate doses, this appears to be quite safe. I suggest taking no more than 1,000 milligrams (one gram) of fish-oil based omega-3s per day.

For people with very high blood triglyceride levels, high-dose omega-3 pills are an effective treatment. These pills (known as Lovaza) are available by prescription. The usual dose is 4 grams per day.

What Can I Expect Looking to the Future?

As we have seen with other supplements, such as vitamin E, the scientific evidence supporting health benefits from fish oil does not live up to the hype. Is this the final word on omega-3s? Probably not.