What are the important nutritional differences between plant and animal sources of protein?

Question

Which food source supplies complete protein and which supplies incomplete protein?

Answer 1

Animal protein is complete protein and vegetable or plant protein is mostly incomplete protein.

Complete protein requires adequate amounts of all 8 of the essential amino acids including lysine and methionine.  Bread, cereals, pasta and rice are low in lysine so they are mostly incomplete protein.  Beans, peas, lentils and nuts are low in methionine so they are mostly incomplete protein.

When you combine the above lysine deficient foods with the above methionine deficient foods you get complete protein and this is known as protein complementing.