Due mainly to the availability of canned tuna, Americans consume more tuna than any other type of fish, according to the "Encyclopedia of Human Nutrition." Both canned and fresh tuna are available throughout the year, although the canned varieties are considerably cheaper. Tuna is considered a very good source of magnesium, which is an essential mineral needed by your body for numerous functions. Despite all the healthy nutrients that tuna contains, the U.S. Food and Drug Administration, or FDA, warns of potential mercury poisoning and recommends that pregnant and nursing women limit their intake.
About Tuna
Tuna is fished in the Pacific, Atlantic and Indian oceans, as well as the Mediterranean Sea. It provides a firm and dense flesh that has a strong and meaty flavor. Tuna is eaten raw, smoked, pickled, baked and from a can. There are several species of tuna, with yellow-fin and albacore being the most popular, especially for canning. Blue-fin tuna is currently being over-fished and is on the verge of becoming an endangered species. Tuna contains numerous essential nutrients, including minerals such as magnesium.
Nutrients in Tuna
Tuna is a very nutrient-dense food, especially canned varieties. It is an excellent and economical source of high-quality protein, and contains many minerals, vitamins and essential fatty acids. According to the "American Dietetic Association Complete Food and Nutrition Guide," tuna contains selenium, magnesium, potassium, B-complex vitamins, vitamin E and healthy omega-3 fatty acids. Cold-water fish such as tuna are rich sources of omega-3 fatty acids, which account for many of the cardiovascular benefits that fish provide. In terms of magnesium, tuna is considered a very good source. According to "The Healthy Whole Foods Counter," 4 oz. of baked yellow-fin tuna contains about 72 mg of magnesium, which is approximately 18 percent of the recommended daily value.
Importance of Magnesium
Magnesium is the fourth-most abundant mineral in your body and is required for more than 300 biochemical reactions, according to the National Institutes of Health. About half of your body's magnesium is found in bone, where it is needed for structural support, while the other half is found inside tissues and organs, where it is used to maintain muscle tone, nerve function, heart rhythm, blood sugars, blood pressure, metabolic rate and an efficient immune response. Recommended daily allowances for magnesium ranges from 310 mg to 420 mg for adults, depending on age and gender. According to Sari Edelstein, author of "Nutrition and Public Health," magnesium deficiency is increasing in the United States primarily because of mineral-poor soil and the resultant reduced mineral content of fruits and vegetables. As such, tuna may become an even more important source of magnesium in the future.
Cautions
Tuna is a relatively long-lived fish and at the higher end of the food chain, which means it is more likely to consume and accumulate toxins, such as mercury, from industrial waste and contamination of oceans and seas. In 2004, the FDA issued a recommendation that young children and pregnant, nursing and potentially childbearing women consume no more than 6 oz. of canned albacore tuna per week, as cited in the journal "Nutrition Concepts & Controversies." Despite tuna's high nutrient profile, the potentially destructive health effects of mercury warrant caution and moderation.
References
- "Encyclopedia of Human Nutrition"; Benjamin Caballero et al; 2005
- "American Dietetic Association Complete Food and Nutrition Guide: 3rd Edition"; Roberta Larson Duyff; 2006
- "The Healthy Whole Foods Counter"; Annette B. Natow et al; 2008
- National Institutes of Health: Office of Dietary Supplements: Magnesium Fact Sheet
- "Nutrition and Public Health"; Sari Edelstein; 2006
- "Nutrition Concepts & Controversies: 12th Edition"; Frances S. Sizer et al; 2011
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