Although omega-3s, specifically docosahexaenoic acid and eicosapentaenoic acid, are present in tuna, this nutritious fish and omega-3 oils are two entirely different food items. Each provides its own benefits as well as potential drawbacks. Although tuna is packed with essential nutrients your body needs daily, pregnant and nursing women and young children are advised to limit tuna consumption to a few servings -- or less -- per week.

Tuna is an excellent source of dietary protein, which boosts satiety and helps your body burn extra calories, according to a 2008 review published in the “American Journal of Clinical Nutrition.” This is beneficial for healthy weight management. A 3-ounce portion of canned light tuna provides about 17 grams of dietary protein but just 73 calories. Tuna is also a good source of dietary iron, niacin, vitamin B-12, vitamin D and heart-healthy polyunsaturated fatty acids -- including omega 3s. Replacing high-fat meats with tuna can help control your overall calorie intake and may help reduce your risk for obesity and heart disease.

Fish oils are often a more concentrated source of omega-3 fatty acids, especially DHA and EPA, than tuna. Furthermore, fish oils are generally purified, meaning they are free from harmful levels of contaminants, such as mercury, which can be found in tuna. A review published in 2012 in “Advances in Nutrition” reports that omega-3 oils containing DHA and EPA are important for proper fetal development and may help reduce inflammation, heart problems and peripheral artery disease. MedlinePlus reports that fish oil supplements are effective for reducing high triglyceride levels. Taking more than 3 grams of fish oil daily may increase your risk for bleeding, however.

Alpha-linolenic acid, also known as ALA, may have the same heart-healthy benefits as eating tuna and taking fish oil supplements, according to the University of Maryland Medical Center. Furthermore, because ALA is derived from plant-based oils -- such as flaxseed, canola, soy and walnut oils -- it’s often desirable for individuals following vegetarian and vegan diets. ALA can be partially converted to DHA and EPA in your body. A 2012 review published in “Advances in Nutrition,” however, reports that only a small amount of ALA can be converted to DHA and EPA. Vegan omega-3 oils containing plant-based DHA are also available.

While tuna is an excellent source of dietary protein, DHA and EPA, omega-3 oils often contain DHA and EPA -- or ALA -- but no protein. While tuna is a low-calorie food, omega-3 oils are more calorie-dense because fat provides 9 calories in each gram, compared to 4 calories per gram in protein. Purified omega-3 oils generally contain fewer environmental contaminants than tuna, especially albacore, yellowfin, ahi and bigeye tunas. But omega-3 oils are often significantly more expensive than tuna.