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Omega-3-rich foods: Good for your heart

Learn what these essential fatty acids can do for your cardiovascular health, and where to find the best sources.

Back in the 1970s, Danish researchers discovered something curious about the Inuits of Greenland. Despite eating a high-fat diet (about 40% of their daily calories came from fat), the Inuits had far lower rates of heart disease and heart attacks than people in Western nations. When the researchers delved deeper, they discovered one reason for the Inuits’ low rates of heart disease: a seafood-heavy diet rich in the polyunsaturated omega-3 fatty acids—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Since then, investigators have homed in on omega-3s—not just for their cardiovascular benefits, but also for their potential effects on thinking ability, vision, and inflammation.

At least with regard to heart health, “The list of clear, well-established physiologic benefits is quite long,” says Dr. Dariush Mozaffarian, associate professor of medicine and epidemiology at the Harvard School of Public Health. “People who consume more fish have a lower risk of dying from heart disease.” The omega-3s in fish have several heart-healthy effects: they lower heart rate and blood pressure, and they improve the health of blood vessels.

Many of the same advantages omega-3s confer on the heart—including reduced inflammation and lower blood pressure—might also protect the brain. Researchers are currently studying whether omega-3s can prevent or slow cognitive decline, but that still remains to be seen. Omega-3s are also being investigated for their effects on depression and mood disorders, as well as on arthritis, cancer, and a number of other health conditions.

The best sources of omega-3s

Your body can’t manufacture omega-3 fatty acids, so the best place to get them is through diet. There are two dietary sources:

  • EPA and DHA are primarily found in fatty fish, such as salmon, tuna, and anchovies.

  • Alpha-linolenic acid (ALA) comes from vegetable oils, nuts, flaxseeds and flaxseed oil, and leafy vegetables.

Most of the health benefits attributed to omega-3 fatty acids come from EPA and DHA. The body converts ALA into EPA, but only in very small amounts. “The conversion from ALA to EPA is less than 5%, so it’s very low. You pretty much can’t get DHA except from fish,” Dr. Mozaffarian says.

Amount of omega-3 fatty acids in fish

Fish

Serving size

Amount of omeg-3s

Atlantic salmon

3 oz

1,900mg

Sardines, canned

3 oz

1,500mg

Anchovies, canned

2 oz

1,200mg

Atlantic Mackerel

3 oz

1,150mg

Canned salmon

3 oz

1,000 mg

Canned tuna

3 oz

500 mg

Flounder

3 oz

400 mg

Where to get omega-3s

The evidence suggests that eating fatty fish at least twice a week is the best way to reduce heart disease risk with omega-3s. “If you’re already consuming fish two or more times a week, there’s no extra benefit to taking a supplement. If you’re not consuming fish two or more times a week, I would definitely recommend a fish oil supplement,” Dr. Mozaffarian says. If you are considering a supplement, ask your doctor what dose is most appropriate based on your health.

Concerns about mercury shouldn’t stop you from eating fish—or taking fish oil supplements. Mercury generally isn’t a problem unless you’re pregnant or nursing, according to Dr. Mozaffarian. But if you’re still worried, choose fish that are low in mercury and high in omega-3s, like salmon, sardines, trout, and canned light tuna.

Bad news about omega-3s?

If you’ve been following the news about omega-3 fatty acids, you might have read about a few studies with less-than-positive results. One of the most highly publicized was a 2012 meta-analysis of 20 clinical trials published in The Journal of the American Medical Association. The researchers concluded that supplementing with omega-3 fatty acids didn’t reduce the risk of heart attacks, strokes, or deaths from heart disease. However, many experts—including Dr. Mozaffarian—have raised questions about the study’s methods, because it lumped together results from trials that used very different amounts and sources of omega-3s.

Also, the authors changed the limit researchers typically use for statistical significance. If they had used the standard threshold, omega-3 supplements would have been associated with a significant decrease in heart disease–related deaths. When taken as a whole, research on omega-3s from both diet and supplements does indicate a lower risk of dying from heart disease, Dr. Mozaffarian says. The evidence that omega-3 supplements are brain-healthy isn’t as strong.

Posted by: Dr.Health

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