Omega-6 and omega-3 are essential fatty acids, or EFAs, meaning they are required for good health, but the body can't synthesize them itself efficiently. You must get them from your diet; and tuna is one of the dietary sources of omega-3 EFAs. It contains both eicosapentaenoic acid and docosahexaenoic acid --- or EPA and DEA, respectively --- the omega-3 fatty acids with the greatest health benefits.
Essential Fatty Acids Defined
In the body, the essential fatty acids are critical components of the cell membrane, the material that encloses the contents of the cell. EFAs consist of a long chain of carbon atoms that terminates with a carboxylic acid group. The omega-3s contain 18 to 22 carbon atoms and more than one double bond, meaning they are polyunsaturated. You can decrease your risk of coronary artery disease by consuming polyunsaturated fats like the omega-3 fatty acids.
Eicosapentaenoic Acid
Tuna is a dietary source of the omega-3 EPA. The health benefits of EPA are concentrated in cardiovascular disease prevention. It has beneficial effects on coronary heart disease, triglyceride levels, high blood pressure and inflammation. In an article in the March 2007 issue of "Lancet," researchers disclosed the results of a large clinical trial on the cardiac effects of EPA in Japanese people with high cholesterol. The scientists found that after 4.6 years of study, those patients who received 1,800 mg of EPA per day along with a statin drug sustained 19 percent fewer major coronary events relative to those who got only the statin. Major coronary events included sudden cardiac death, fatal and non-fatal heart attacks, unstable angina pectoris and certain coronary surgical procedures.
Docosahexaenoic Acid
The omega-3 DHA has beneficial effects on brain function and the cardiovascular system of adults, and it supports the proper development of the vision and the central nervous systems in infants. All types of tuna --- bluefin, skipjack, yellowfin and albacore --- contain DHA, but bluefin supplies more per serving than the other types. If you take a prescription medication to lower your blood pressure, you should be aware that DHA may increase the effectiveness of this medication, leading to a potentially unsafe decrease in your blood pressure.
Tuna Comparison
Canned tuna packed in water is preferable to that packed in oil. The reason is the omega-3 essential fatty acids dissolve in the oil, so when you pour off the oil, you are losing some of the fatty acids. But since fatty acids do not dissolve in water, you lose very little of them when you pour off the water. In addition, a 3-oz. serving of canned white tuna contains a total of 0.74 g of omega-3 essential fatty acids, EPA plus DHA, while the same serving of canned light tuna contains a total of 0.23 g. As for fresh tuna, bluefin contains 1.17 g of omega-3 fatty acids per 100 g serving while yellowfin contains 0.23 g per 100 g serving, according to the Environmental Defense Fund.
References
- Oregon State University; Essential Fatty Acids; Jane Higdon; December 2005
- Milton S. Hershey Medical Center; Eicosapentaenoic Acid (EPA); September 2010
- University of Maryland Medical Center; Docosahexaenoic Acid (DHA); September 2008
- Tufts University School of Medicine; Omega-3 Fatty Acids; March 2002
- Readersdigestversion.com: Why Your Diet Needs to Go Fish
- Environmental Defense Fund: Bluefin Tuna
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