Isoleucine and leucine are two essential amino acids that must be supplied by your diet. Amino acids are the building blocks of protein and isoleucine and leucine are two of the three branched-chain amino acids that maintain muscle mass and are needed during vigorous exercise and intense physical stress. Sources of isoleucine and leucine include animal proteins and are best absorbed with B vitamins.
Soy Protein Isolate
Soy protein isolate and soy protein concentrate are made when the fats and carbohydrates are separated and removed from from the soybean, leaving only the protein. Higher in isoleucine and leucine than any other protein, including animal proteins, there are over 4000mg of isoleucine per 100g of soy protein.
Bacon, Eggs and Sausage
Eggs are very high in isoleucine, with 2500mg per 100g. Egg whites have more amino acids than the yolks. Sausage has 2200mg and bacon has 1800mg of isoleucine and even high amounts of leucine per 100g serving.
Cod and Other Fish
Atlantic cod, either fresh or salted and dried, has more branched chain amino acids than any other fish with 2900mg of isoleucine and 5g of leucine in 100g. Other fish that are good sources of isoleucine and leucine are Alaskan whitefish and Alaskan smelts.
Cheese and Milk
Parmesan cheese, non-fat milk and buttermilk all have between 2100 and 2200mg of isoleucine, but contain less leucine. Gruyere and romano cheeses are good sources of leucine as well. Nonfat milk has more leucine than buttermilk.
Spirulina
Spirulina is a type of seaweed and is considered a vegetable. Soybeans and spirulina are the only vegetable sources for amino acids of note. Spirulina contains 3300mg of isoleucine and 5000mg of leucine per 100g serving.
Nuts and Seeds
Almonds, cashews and sesame seeds are all high in branched chain amino acids. Nuts and seeds can be eaten raw, roasted, made into nut butters and tahini or made into flour and still contain the same amount of leucine and isoleucine.
Red Meat
Bison, veal and beef contain some branched chain amino acids, but are higher in other amino acids such as lysine, glutamic acid and aspartic acid. They are still excellent sources of protein and contain all amino acids, including leucine and isoleucine.
