Popular omega-3 supplements may not have the same heart health benefits for everyone, but research shows they can be key for lowering blood pressure and triglycerides.

The nutritional-supplement business continues to expand as Americans look to reduce their risk factors for major diseases, including heart disease.

Makers of omega-3 fatty acid supplements, specifically, posted sales of $25.42 billion in 2011, with a 15 percent growth rate each year, according to Research and Markets. But whether these supplements can deliver the results they promise is uncertain.

Omega-3 fatty acids, found naturally in many foods and widely available in supplement form, are often touted for their heart health benefits. But a new study shows that some of the people most in need don’t get any benefit from taking them.

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The study, published in the American Medical Association journal Internal Medicine, examined the effects of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on a group of people with an average age of 74. These particular participants had heart problems, as well as age-related vision loss in at least one eye.

The study showed that daily supplementation of these omega-3 fatty acids had no statistically significant effect on the risk of cardiovascular events, including heart disease and stroke, in 4,203 people whose ages ranged from 50 to 85.

However, the researchers did point out shortcomings in their findings, noting that getting more omega-3s through one’s diet may have yielded different results, and that supplementation may have come too late to affect health outcomes for these patients.

“We cannot exclude a beneficial effect from starting supplementation earlier in life,” the researchers concluded.

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Adam Ismail, executive director of the Global Organization for EPA and DHA Omega-3s (GOED), a trade group dedicated to increasing the consumption of EPA and DHA, called the study “underpowered” because too few patients participated.

“Even though this study was underpowered, they did find some benefits [of omega 3s],” he told Healthline.

In an editorial accompanying the research, Dr. Evangelos Rizos and Dr. Evangelia Ntzani wrote that 22 randomized clinical trials on the effectiveness of omega-3 supplementation for preventing cardiovascular events showed “no clear, considerable benefit,” and that funding further studies seemed unjustified.

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Rizos and Ntzani say that, based on the available evidence, omega-3 fatty acid supplementation is justified only for people with severe hypertriglyceridemia, which affects an extreme minority of the general population.

But other research has shown that omega-3s are effective for reducing triglyceride levels and blood pressure—two major risk factors for heart attack, stroke, and other events.

Another study, which was published in the American Journal of Hypertension and funded by the GOED, reviewed 70 randomized controlled trials and found that EPA and DHA supplementation reduced a person’s blood pressure, especially in people with untreated hypertension.

“What it found was that omega-3s reduce blood pressure—both systolic and dystonic pressure—equivalent to other lifestyle changes,” Ismail said.

Ismail recommends daily supplementation with 250 to 500 milligrams of EPA and DHA.

The American Heart Association’s Heart-Check Food Certification Program recommends that people with a higher risk of health problems eat fatty fish containing 500 milligrams of omega-3s for every three ounces of cooked fish to reduce triglyceride levels.

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