The healthy effects of fish outweigh the risks from mercury when it comes to lowering heart attack risk -- so long as the type of fish is low in the hazardous chemical, according to a small new study.

Researchers from Umea University found that high omega-3 fatty acids in fish were linked with a lower risk of heart attack, but high levels of mercury in fish raise risk of heart attack -- especially when the fish with high mercury levels also had low omega-3 levels. In order to maximize the benefits of the omega 3-s, researchers advised people to choose fish with low levels of mercury and high levels of omega-3s.

The study was based on levels of methylmercury and omega-3 fatty acids in a total of 572 men from Finland and Sweden by examining samples of their blood and hair. It was published in the American Journal of Clinical Nutrition.

Similarly, a recent Arizona State Universty study in the journal Frontiers in Ecology and the Environment, showed that sustainable fish tend to have lower concentrations of mercury than unsustainable seafood. Therefore, researchers said, if you want to pick the most healthful fish, go for the sustainable kind.

Nearly every kind of fish contains mercury, but some contain higher levels than others, according to the Environmental Protection Agency. Mercury can be especially dangerous for pregnant women because it can affect how the child develops. The EPA recommends against eating shark, king mackerel, tilefish and swordfish because of their high levels of mercury; fish known to be lower in mercury include shrimp, salmon, catfish, pollock and canned light tuna (which has lower mercury levels than albacore tuna).

While the new study suggests a protective benefit of eating fish for the heart (especially if the fish is low in mercury), a recent review of studies was less positive about the heart-protective effects of fish oil. That review, published in the Journal of the American Medical Association, included 20 studies and showed that omega-3 supplementation doesn't seem to lower heart attack or stroke risks, WebMD reported.

"It may be that food sources of omega-3, rather than supplements, are a better choice," Dr. David A. Friedman, M.D., of the North Shore-LIJ Plainview Hospital in New York who was not involved in that study, told WebMD.

Not a fan of fish? Check out these vegetarian options for getting your omega-3s from our partner Blisstree.com:

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  • Flaxseed Or Flaxseed Oil

    Flaxseed is one of the most highly-recommended plant sources for omega-3s. Ground flaxseed is a staple in my kitchen -- it keeps for a long time in the freezer, and because flaxseed is virtually tasteless, I throw it in all sorts of things -- cereal, oatmeal, smoothies -- to boost my omega-3 intake. You can use ground flaxseed goo as an egg substitute in vegan baking. Flaxseed oil has <a href="http://www.krispin.com/omega3.html#Supplementing" target="_hplink">7980 mg omega-3's per 1-tbsp serving</a>. <strong>More from Blisstree.com:</strong> <a href="http://blisstree.com/move/best-fitness-trackers-similar-to-the-nike-fuel-band-658/" target="_hplink">The Best Fitness Trackers</a> <a href="http://blisstree.com/eat/supplements/which-is-better-krill-oil-or-fish-oil-841/" target="_hplink">Krill Oil vs. Fish Oil</a> <a href="http://blisstree.com/feel/eat-for-your-teeth-omega-3s-could-prevent-gum-disease/" target="_hplink">Eat for Your Teeth: Omega 3s Could Prevent Gum Disease</a> <em>Flickr photo by <a href="http://www.flickr.com/photos/alishav/3462217890/" target="_hplink">Alisha Vargas</a></em>

  • Chia Seeds

    Chia seeds are another plant source of omega-3's that I like to sneak into my diet. You can throw chia seeds into stir fry, salads, seitan, dips and more. Like ground flaxseed, chia seeds have a mild -- if any -- taste. But they'll add a dose of omega-3's and a slight crunch wherever they're added. <em>Flickr photo by <a href="http://www.flickr.com/photos/notahipster/4998594527/" target="_hplink">little blue hen</a></em>

  • Hemp Seeds

    Vegan and gluten-free, hemp seeds also have the most essential fatty acids of any nuts or seeds and a perfect 3:1 <a href="http://today.msnbc.msn.com/id/16637630/ns/today-food/t/nutty-hemp-hot-food-trend/" target="_hplink">ratio of omega-3 to omega-6</a>. They're also high in protein, minerals and rare polyunsaturated fatty acids like gamma-linolenic acid (GLA) and stearidonic acid (SDA). Like flax and chia seeds, you can sprinkle hemp seeds into lots of different things. Store in the freezer to keep them from going bad. <em>Flickr photo by <a href="http://www.flickr.com/photos/restlessglobetrotter/3425782783/" target="_hplink">Jason Rogers</a></em>

  • Perilla Oil

    Perilla oil comes from the seeds of the herb perilla. Over 50 percent of perilla oil consists of ALA, with about <a href="http://www.krispin.com/omega3.html#Supplementing" target="_hplink">8960 mg omega-3 fatty acids</a> per tablespoon (compared to 1680 mg omega-6's).

  • Cauliflower

    "Many people are not aware that cauliflower contains a good amount of omega-3 essential fatty acids, making this veggie great for heart health," says nutritionist Margaux Rathbun. "In addition to the omega-3, cauliflower contains other heart-friendly nutrients including potassium, magnesium and niacin." <a href="http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2390/2" target="_hplink">One cup contains about 37 mg of omega-3's</a>. To retain the nutrients in cauliflower, Rathbun recommends steaming it for no more than five to six minutes, then adding lemon juice and cold-pressed extra-virgin olive oil. <em>Flickr photo by <a href="http://www.flickr.com/photos/wordridden/4626951567/" target="_hplink">Jessica Spengler</a></em>

  • Hummus

    "Hummus is a vegan source of omega-3's," with about 300 mg in a one-cup serving, explains Charis Freiman-Mendel, author of "Cook Your Way Through the S.A.T.". That's because hummus is made with tahini, which is made from omega-3-packed sesame seeds. "Delicious, healthy, great brain food," says Freiman-Mendel. <em>Flickr photo by <a href="http://www.flickr.com/photos/alga/3122887625/" target="_hplink">Albertas Agejevas</a></em>

  • Purslane

    Purslane is a salad or cooking green with a slightly peppery taste. It's got <a href="http://www.health.com/health/gallery/0,,20487719_5,00.html" target="_hplink">400 mg of omega-3's per serving</a>. It's also high in <a href="http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2604/2" target="_hplink">vitamin A</a>, calcium, potassium and iron.

  • Brussels Sprouts

    One serving of Brussels sprouts contains about 430 milligrams of alpha-linolenic acid -- more than one-third of the <a href="http://www.nal.usda.gov/fnic/DRI//DRI_Energy/energy_full_report.pdf" target="_hplink">daily ALA amount recommended</a> by the National Academy of Sciences. "These tasty little green veggies are loaded with nutrients, including omega-3 fatty acids," says nutritionist Margaux Rathbun. "They're the perfect food for promoting healthy and beautiful skin. Try steaming them for about five minutes to keep all of the health-promoting nutrients intact." <strong>More from Blisstree.com:</strong> <a href="http://blisstree.com/move/best-fitness-trackers-similar-to-the-nike-fuel-band-658/" target="_hplink">The Best Fitness Trackers</a> <a href="http://blisstree.com/eat/supplements/which-is-better-krill-oil-or-fish-oil-841/" target="_hplink">Krill Oil vs. Fish Oil</a> <a href="http://blisstree.com/feel/eat-for-your-teeth-omega-3s-could-prevent-gum-disease/" target="_hplink">Eat for Your Teeth: Omega 3s Could Prevent Gum Disease</a> <em>Flickr photo by <a href="http://www.flickr.com/photos/39975765@N05/6399983389/" target="_hplink">Mallory Dash</a></em>

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