The steak with the most protein isn't beef — it's this

Steak is a favorite among those looking to build muscle through protein intake. Beef steak is the most common choice, but tuna, pork, salmon and cod actually contain more protein.

Protein content varies depending on the cut, breed and cooking method of the ingredient. Meat in particular shows large differences depending on the cut. Sirloin and tenderloin — which have a moderate amount of fat and a firm texture — are commonly used for steaks.

Real Food examined the protein content of six cuts commonly used for steak — beef and pork sirloin, chicken breast, salmon, cod and tuna (the red meat of bluefin tuna). The analysis used the Ministry of Food and Drug Safety's food nutrition database. Tuna showed the highest protein content, followed by pork sirloin, chicken breast, salmon, cod and then beef tenderloin (Grade 1 Hanwoo). Cod had the lowest fat and calorie content.

Tuna steak made from the red meat of bluefin tuna contains 26.4 grams of protein and 1.4 grams of fat per 100 grams raw (the same measurement basis applies throughout this article). Tuna steak is mainly made from red meat cut horizontally from the back of the fish. This section has only 2 to 5 percent fat, giving it a high protein density.

However, bluefin tuna steak is relatively expensive, and excessive consumption raises concerns about mercury. Raw tuna eaten as steak or sashimi comes from a different species than the skipjack tuna used for canned tuna. Canned tuna mainly uses the smaller skipjack, while steak uses larger species such as bluefin, yellowfin and bigeye tuna. The Ministry of Food and Drug Safety recommends limiting intake to about 100 grams or less, roughly once a week. Bluefin tuna's mercury content is 48 times higher than that of skipjack.

Among the beef and pork cuts commonly used for steak — tenderloin and sirloin — pork sirloin had a higher protein content than beef. Pork sirloin contains 23.3 grams of protein, while beef tenderloin (Grade 1 Hanwoo) contains 19.1 grams and beef sirloin contains 18.6 grams.

Beef sirloin has the highest fat content, at 24.5 grams — 5.4 times more than pork sirloin's 4.5 grams. The higher the grade of beef, the more marbling, or intramuscular fat, it carries, raising its fat content.

Chicken breast, a staple protein food, contains 22.9 grams of protein. Its fat content, at 0.9 grams, is the second-lowest after cod.

Salmon contains 20.6 grams of protein. Its fat content, at 1.9 grams, is higher than that of cod or tuna, but more than three-quarters of that fat is unsaturated fat beneficial to the body, particularly omega-3. This gives salmon the advantage of offering high protein along with omega-3, compared with meat, which tends to be higher in saturated fat.

Cod, by contrast, is a low-fat, high-protein white fish, containing just 0.3 grams of fat per 100 grams — the lowest fat and calorie content among the six foods examined. Its mild, non-fishy taste has made it a popular steak choice for dieters.

Experts recommend cod steak for those seeking a low-fat, low-calorie option, and salmon steak for those who also want unsaturated fat. Among red meats, pork sirloin is recommended for its mild taste and lower fat content, while high-grade Hanwoo sirloin or strip loin suits those who want rich juiciness and marbling.