Which of the following is considered an incomplete protein?

An incomplete protein is defined as a protein that does not contain all nine essential amino acids required by the body. These essential amino acids must be obtained through diet because the body cannot synthesize them.

Corn is considered an incomplete protein because it lacks certain essential amino acids, particularly lysine and tryptophan, which are necessary for various bodily functions. As a grain, corn provides some protein content but does not meet the full amino acid profile required for a complete protein source.

On the other hand, fish, eggs, and chicken are all complete proteins, meaning they contain adequate amounts of all essential amino acids. They are derived from animal sources, which typically have a more balanced amino acid composition compared to many plant sources. This classification helps in understanding dietary choices for those looking to ensure they consume sufficient protein in their diets.