Protein is important and is an essential part of your diet. Not all proteins are the same, however, as some are surrounded by stuff that's bad for you, like saturated fats.
We want protein because it helps the body make and repair cells. Every one of your cells contains proteins and they're a major part of your muscles, bones, skin and hair. Its basic building blocks are called amino acids and there are 20 such basic amino acids. While the body can make most of these 20 amino acids, it can't make 9 of them. These 9 are called essential amino acids and we must get them from the proteins in our diet.
Based on that, there are different types of protein in food that are considered either complete or incomplete. For example, animal proteins generally contain all the essential amino acids, so they're considered complete. On the other hand, proteins from fruits, veggies, grains and nuts are missing at least one essential amino acid, so they are considered incomplete.
It's best to eat a mix of proteins because different sources of protein offer different benefits. When protein is eaten from smart sources and in sensible portions, they're the foundation of a healthy, balanced diet.
In this video, Registered Dietitian Lynn Goldstein further explains what a complete protein is, what food can give us the highest amount of protein and why “All protein diets” are not good for your health.