Canned tuna is inexpensive and packed with protein. The fish is mild in flavor and versatile enough to include in a variety of nutritious recipes. Opt for tuna canned in water, and a serving contains less than 1 gram of fat and only about 100 calories. You'll also get a good dose iron and potassium as well. While you shouldn't eat tuna every day because of its mercury content, you can still safely enjoy canned tuna as a regular part of your healthy eating plan.