Macronutrients in our diet:

Proteins
Proteins are substances that make up your muscles, bones, cartilage, skin, and antibodies as well as some of the hormones and all the enzymes in your body. Proteins in food are broken down in the intestine into amino acids, the building blocks for proteins in your body.

The body can manufacture 13 of the 22 amino acids present in proteins; these 13 are called non-essential amino acids because they do not need to be obtained from the diet. The other nine are known as essential amino acids because they must be supplied by the food you eat.