The amino acids are the components of protein. Protein is built in your liver from amino acids, like a puzzle.
We are made by protein, and our body builds a different kind of proteins to build different components: Muscle, bones, tendons, skin, hair, nails, and different tissues.
Every tissue has its own aminogram, it means, a different composition of amino acids, so we have Collagen type 1 for the skin, bones, and tendons, Collagen Type II for cartilage, and muscle aminogram for muscle, in the example.
We have 2 types of amino acids:
Essentials: The ones our body can´t build and need to get them from food
Non-essentials: The ones our body can build by itself.
The amount of protein that we see in the food label is the sum in grams of every amino acid it has, so here is why we consider one protein better than others, depending on the quality of the aminogram of this food, and the amount in Essential amino acids.
To build the protein, our body needs to have all the 9 essential amino acids, so when one is missed no protein is built.
To complete this 9 essential amino acid we can combine all the ingredients in a meal, so normally we should form a complete protein, but also the body needs the right minimum amount for each one, that's why depending on the combination we can build more or less protein.
For years is been told that eggs have the most similar aminogram to our body, so eggs are considered a high balanced protein. Anyway, eggs are balanced protein, we are not an egg, we are skin, muscle, bones,...that's why supplementing with different types of protein can help to improve our muscles, skin or bones.
BCAA: Branched-chain amino acids, are the amino acids involved in protein synthesis, so they are especially important for athletes. Moreover are in muscle contraction and reducing fatigue.