Lysine is one of the most commonly mentioned essential amino acids. Foods such as bread and rice tend to be low in lysine.
For example, compared to an ideal amino acid composition, wheat is low in lysine.
It can not be said that it is a good quality protein.
The United Nations University carried out the research about people in developing countries where they depend on wheat for protein, and found out the lack of lysine in their diet. Not having enough lysine and other amino acids can lead to serious problems such as stunted growth and severe illness.
To make grains more nutritious it should be supplemented with the amino acids that it lacks.