Some popular forms of canned tuna contain much lower amounts of omega-3 fatty acids than recommended for cardiovascular health while measuring high in levels of mercury and arsenic.

This disturbing evidence was discovered by Dr. Tod Cooperman, president of ConsumerLab.com. His researchers analyzed 14 popular brans of canned tuna and salmon products sold in the U.S. and found that the total amounts of DHA and EPA, the omega fatty acids that are heart healthy, ranged as low as 45 milligrams per serving to over 1,200 milligrams. To reduce the risk of heart disease, it’s recommended that fish or seafood provides an average of 250 milligrams of omega-3 fatty acids per serving.

In general, of all the products tested, canned salmon was more beneficial to cardiovascular health as it had more of the necessary omega-3s than canned tuna.

Furthermore, researchers discovered that half the products were contaminated with mercury and/or arsenic at levels that suggest they should not be be eaten more than once or twice a week, says Cooperman. The most common culprits were found in tins of albacore tuna.

“Canned tuna or salmon can be an inexpensive and convenient way to get protein, omega-3s, and other key nutrients,” Cooperman tells Newsmax. “Unfortunately, according to our tests, many canned fish don’t provide enough omega-3s and are contaminated to the point that their use should be limited. In many cases, switching from albacore or solid white tuna to another form of tuna or salmon appears to be a healthful move.”

The new findings are online now in ConsumerLabs.com’s Canned Tuna and Salmon Review which includes the top picks — products with a significant amount of DHA and EPA with minimal contamination at a good price, as little as 60 to 80 cents per serving.

Among the top picks was Genova Yellowfin Tuna in Extra Virgin Oil. This brand contains a modest amount of omega-3s — 22.5 mg of EPA and 145.6 mg of DHA — at a reasonable cost, and it is packed in flavorful, healthy olive oil.

By contrast, StarKist Selects Solid Yellowfin Tuna in Extra Virgin Olive Oil had less than half the DHA, no quantifiable EPA, and the greatest concentration of arsenic of any of the products tested.

Among the top picks of canned salmon, Deming’s Red Sockeye Salmon has a super amount of DHA (472.5 mg.) and EPA (227.2 mg) with very little contamination. A large, 14.75-ounce can costs only $5.47.

Kirkland’s Signature Wild Alaskan Pink Salmon also scored top marks with 285.6 mg of DHA and 110.8 mg of EPA. On top of that, a 2-ounce serving costs only 72 cents which Cooperman says is an extremely good health buy for the money, if you prefer a milder tasting salmon than red and want to get away from albacore tuna.

When shopping for canned fish, you should also look for the “Dolphin Safe” seal on the label and the Certified Sustainable MSC seal. The first indicates that no dolphins were killed or seriously injured when the tuna was caught and the second seal means that the fishery has been certified by the Marine Stewards Council which set standards for sustainability.

Founded in 1999, ConsumerLab.com is a leading provider of consumer information and independent evaluations of products affecting health and nutrition. Membership is available online.