Eating fish just once or twice per week may reduce your chance of dying from a heart attack by a third, says MayoClinic.com. Tuna is rich in omega-3 fatty acids, among other valuable nutrients. Tuna steak is very different than the canned version, and is often served cooked rare, crusted with spices or sesame seeds.

Bluefin tuna and yellowfin, or ahi, tuna are the two types most commonly served in steak form. Bluefin is fattier with dark red meat that looks a lot like beef. Bluefin is the kind you often find in sushi restaurants. Yellowfin tuna is more common than bluefin and has a light, pale-pink flesh. Albacore and skipjack tuna are rarely served as steaks and are most often canned.

In 3 oz. of yellowfin tuna steak there are 110 calories, .5 g of fat and 24.78 g of protein. Three oz. of bluefin tuna steak has 156 calories, 5.34 g of fat and 25 g of protein. There are no carbohydrates in tuna.

Bluefin tuna is slightly higher in iron than yellowfin tuna. Both are good sources of the amino acid tryptophan and the B vitamins niacin, pyridoxine and thiamin. A 4-oz. serving of yellowfin tuna offers 75.8 percent of the daily recommended allowance for selenium, while bluefin contains slightly less. Tuna steak is a good source of potassium, with about 18 percent of the RDA.

Although salmon and mackerel are considered the best sources, tuna is still a good source of unsaturated fats, particularly omega-3 fatty acids. A type of unsaturated fatty acids, omega-3s may help to reduce inflammation throughout the body and contribute to health. MayoClinic.com notes that the benefits that correlate with omega-3 intake include improved immunity, decreased cholesterol levels and lower blood pressure. Four ounces of yellowfin tuna contains almost 14 percent of the recommended daily value, says the World’s Healthiest Foods.

Tuna steak may have higher levels of methyl mercury than smaller fish. The exact amounts a fish contains depends on its age, size and where it comes from. While pregnant and breastfeeding women and young children should be especially careful to not consume fish, like some tuna, shark and tilefish, that contain high amounts of mercury, the average person who eats just two servings of fish per week obtains more benefits from eating a omega-3 rich fish such as tuna steak than risks associated with mercury contamination.