One of the dietary axioms of the last few years has been, "Eat less red meat and more fish." Fish has less saturated fat and more omega-3 fatty acids than red meat, which might benefit your heart by reducing cholesterol levels and preventing atherosclerosis. Opening a can of tuna is easier -- and doesn't smell up your house as much as cooking fish -- but you might wonder if it's as beneficial as fresh fish. The answer depends on which type of canned tuna you're using and how it's packaged.
Types of Fatty Acid
The type of fats most associated with positive health benefits in fish are omega-3 fatty acids, especially eicosapentaenoic acid, better known as EPA, and docosahexaenoic acid, or DHA. Omega-3 fatty acids reduce inflammation in the body, where omega-6 fatty acids such as linoleic acid tend to promote it. The American diet is high in omega-6 fatty acids and low in omega-3 fatty acids, but few foods outside of fish supply omega-3 fatty acids. Some canned tunas supply more omega-3 fatty acids than fresh fish, according to the University of Minnesota Extension.
Types of Canned Tuna
White albacore and bluefin tuna contain more omega-3 fatty acids than any other type of canned tuna, according to the Seafood Health Facts website, a collaborative site sponsored by Oregon State University, Cornell University, the Universities of Delaware, Rhode Island, Florida & California and the Community Seafood Initiative. Bluefin generally is used to make sushi, not canned tuna. Skipjack and yellowfin tuna, the most common tunas in light canned tuna, contain the next highest amounts of omega-3s.
Oil vs. Water
Tuna packed with oil has less omega-3 fatty acid benefit than tuna packed in water. The oil draws the fatty acids from the fish, so when you drain the packing oil from the can, you lose some of the fatty acids as well. You can lose as much as 25 percent of the tuna's fatty acids when you use oil-packed tuna, compared to a 3-percent loss for water-packed tuna, according to the Woman's Clinic of Monroe. White albacore canned in water contained the largest amount of DHA and EPA in a study reported in the 2004 "Journal of Food Science."
Although albacore tuna is high in omega-3 fatty acids, it's also high in mercury, an industrial contaminant that can cause neurological problems when ingested in large quantities. In the study reported in the 2004 "Journal of Food Science," albacore canned in water contained four times the mercury found in canned light tuna or canned salmon and mackerel. The U.S. Food and Drug Administration recommends limiting canned tuna intake to 12 ounces of canned light tuna or 6 ounces of albacore tuna for women of childbearing age and children.
Some manufacturers market their albacore tuna as low in mercury, with just half the mercury of most albacore tuna, because they catch smaller fish. Smaller fish have less time to accumulate mercury in their tissues than larger varieties. Ask your doctor about these brands and the amount that's safe to include in your diet.
- Journal of Food Science: Mercury and Fatty Acids in Canned Tuna, Salmon and Mackerel
- Seafood Health Facts: Canned Tuna
- University of Minnesota Extension: Beyond Fish Sticks
- University of Maryland Medical Center: Omega-3 Fatty Acids
- The Woman's Clinic of Monroe: Omega-3 Fatty Acids (fish Oil)
- FDA.gov: What You Need to Know About Mercury in Fish and Shellfish
- Swanson Health Products: Low Mercury Wild Albacore Tuna
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