A complete protein (or whole protein) is a source of protein that contains an adequate proportion of all nine of the essential amino acids necessary for the dietary needs of humans or other animals.
The following table lists the optimal profile of the essential amino acids, which comprises complete protein, as recommended by the Institute of Medicine’s Food and Nutrition Board:
Essential Amino Acid mg/g of Protein
The following table shows the amino acid requirements of adults as recommended by the World Health Organization calculated for a 62-kilogram adult, and the amino acid profile of 2530 kilocalories of baked potatoes (9 large baked potatoes), which comprise a day’s worth of calories for a 62-kilogram (136 lb) adult:
Essential Amino Acid Requirement /day/62 kg adult 9 large baked potatoes
Tryptophan 248 565
Threonine 930 1830
Isoleucine 1240 1830
Leucine 2418 2691
Lysine 1860 2933
Methionine+Cystine 930 1534
Phenylalanine+Tyrosine 1550 3553
Valine 1612 2682
Histidine 620 942
Nearly all foods contain all twenty amino acids in some quantity, and nearly all animal foods contain the essential amino acids in sufficient quantity. Proportions vary, however, and most plant foods are deficient in one or more of the essential amino acids. Though some vegetable sources of protein contain sufficient values of all essential amino acids, many are lower in one or more essential amino acids than animal sources, especially lysine, and to a lesser extent methionine and threonine. Consuming a mixture of plant-based protein sources can increase the biological value of food. For example, to obtain 25 grams of complete protein from canned pinto beans requires consuming 492 grams (423 kcal); however, only 364 g of pinto beans (391 kcal) are required if they are combined with 12 grams of Brazil nuts. Complementary proteins need not be eaten at the same meal for your body to use them together. Studies now show that your body can combine complementary proteins that are eaten over the course of the day.
Sources of complete protein:
Generally, proteins derived from animal foods (meats, fish, poultry, milk, eggs) are complete. Proteins derived from plant foods (legumes, seeds, grains, and vegetables) can be complete as well (examples include potatoes, chickpeas, black beans, kidney beans, pumpkin seeds, Cashews, cauliflower, quinoa, pistachios, turnip greens, black-eyed peas, Kasha, and soy).
Certain traditional dishes, such as Mexican beans (legumes) and corn (Poaceae), Japanese soybeans (legumes) and rice (Poaceae), Cajun red beans (legumes) and rice, or Indian dal (legumes) and rice or roti (both Poaceae) combine legumes with grains to provide a meal that is high in all essential amino acids.
Foods that also obtain the highest possible Protein Digestibility Corrected Amino Acid Score (PDCAAS) score of 1.0 are certain dairy products (including whey), egg whites, and soy protein isolate. Other foods, such as amaranth, buckwheat, hempseed, meat, poultry, Salvia hispanica, soybeans, quinoa, seafood, seaweed, and spirulina also are complete protein foods, but may not obtain a PDCAAS score of 1.0.
Meal replacements and bodybuilding supplements based on whey protein, casein, egg albumen protein and other animal foods are considered complete protein. Vegan protein meal replacement and supplements based on individual plants (brown rice, yellow pea) are often deficient in one or more essential amino acids, while soy protein derived from soybean is complete. Very often, plant based meal replacements and supplements are made from plant protein blends, thus creating complete protein sources.