Amino acids are the building blocks of proteins, so the foods with the highest amount of amino acids are those that are highest in protein. Of the 20 amino acids, nine are essential because your body can't make them. Animal-based foods contain all of the essential amino acids, while most plant-based protein sources are low in one or more of the essential amino acids.
Red meat is one of the foods highest in protein, with lean cuts of beef providing about 31 grams in each 3-ounce serving. Ham and pork sirloin roast each provide about 28 grams of protein per 3-ounce serving, and pork chops contain about 21 grams per 3-ounce serving. Fattier cuts of meat are lower in protein per gram.
Poultry and Seafood
You don't have to eat red meat to get a good protein and amino acid fix. A 3-ounce serving of chicken or turkey breast has about 28 grams of protein, and the same amount of halibut, tuna or salmon contains about 22 grams. Tilapia, cod, sole, flounder and perch are slightly lower in protein but are still good sources.
Eggs and Dairy
You can get a significant amount of the necessary amino acids from eggs and dairy foods. When it comes to dairy products, low-fat and non-fat sources provide the most protein per gram and per calorie. A 1-ounce slice of non-fat mozzarella provides 9 grams of protein, while the same amount of low-fat Swiss cheese contains 8 grams. Each ounce of Parmesan cheese has 10 grams of protein. A cup of yogurt provides 14 grams of protein, and a large egg has 6 grams of protein.
Plant-Based Protein Sources
Unlike most other plant-based protein sources, quinoa and soy products provide all of the essential amino acids. A cup of cooked quinoa has about 8 grams of protein, a 3-ounce serving of tofu has 6 grams of protein and a cup of soybeans has 29 grams of protein. Beans and nuts, which don't contain all the amino acids, do provide significant amounts of protein, with beans providing between 15 and 17 grams of protein per cup and nuts and seeds providing between 4 and 9 grams of protein per ounce.