A complete 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. Some incomplete protein sources may contain all essential amino acids, but a complete protein contains them in correct proportions for supporting biological functions in the human body.

Nearly all foods contain all twenty amino acids in some quantity. Proportions may vary and some foods are deficient in one or more of the essential amino acids.

Consuming a mixture of plant-based protein sources can increase the biological value of food.

Generally, proteins derived from animal foods (meats, fish, poultry, cheese, eggs, yogurt and milk) are complete, though gelatin is an exception. Proteins derived from plant foods (legumes, grains and vegetables) tend to have less of one or more essential amino acid.

Some foods contain all the essential amino acids on their own in a sufficient amount to qualify as a complete protein. Complete protein foods that also obtain the highest possible Protein Digestibility Corrected Amino Acid Score (PDCAAS) score of 1.0 are certain dairy products including whey protein, egg whites and soy protein isolate. Other foods, such as buckwheat, hempseed, meat, poultry, soybeans, quinoa, seafood and spirulina also are complete protein foods, but may not obtain a PDCAAS score of 1.0.

Here is a list of Essential Amino Acids, that are complete proteins:

• Tryptophan
• Threonine
• Isoleucine
• Leucine
• Lysine
• Methionine+Cystine
• Phenylalanine+Tyrosine
• Valine
• Histidine