Main source of nitrogen
They are made of amino acids, some of which are essential
Biological value: ability to contribute to tissue formation (nitrogen content)
High biological value or complete proteins are those containing all the essential amino acids.
|Animal proteins||Vegetable proteins|
Vegetable proteins have lower biological value: cereals have little lysine; corn lacks lysine and tryptophan; legumes have limited amounts of methionine. They can be completed by combination: ex. pasta + legumes.