Question

What is meant by complete and incomplete when talking about amino acids?

Answer 1

This centres around the essential amino acids, as explained below.

Explanation:

There are 20 amino acids that the body uses to build proteins. Of these, 9 cannot be made by the body, and must be present in one's diet. These are known as the "essential" amino acids.

A food which contains proteins that has all 9 essential amino acids is said to be a complete protein. If any of the essential acids are missing, the proteins in the food are incomplete.

To my knowledge, all animal-based proteins are complete, but no plant-based proteins are. Therefore, a person on a vegetarian diet must be careful to choice a variety of foods to ensure they get all the essential amino acids.