Protein is found in every cell of the body. All muscles, glands and organs have protein as a major component. It is also present in many of the foods we eat (which is where the body gets most of its protein). Almost every function in the body utilizes protein. Some of the functions requiring protein are:
Protein is a long chain of amino acids—22 different types—all of which our bodies need to function properly.
Amino acids, known as the building blocks of proteins, are chemical compounds (carbon, hydrogen, oxygen, nitrogen) that combine together in different structures to form the many types of proteins that the body requires. One type of protein, for example, is collagen. This is a protein that our body needs for the strength, elasticity and composition of our hair and skin.
Essential and non-essential amino acids
There are two classifications of amino acids: essential and non-essential. Through digestion the proteins we eat are broken down into individual amino acids that are then absorbed and reformed to create new proteins that our body uses. Out of the 22 types of amino acids, 14 are non-essential because they are manufactured by the body and we don’t need to eat certain foods to obtain them. The other 8 amino acids, called the essential amino acids, our body cannot produce so we need to acquire them through the food we eat.
Protein quality is dependent on having all the essential amino acids in the proper proportions.
If one or more of the essential amino acids are not present in sufficient amounts, the protein in a food is considered incomplete and of lower quality.
It’s commonly thought that if all 8 essential amino acids are present in a food, then this food would be considered a complete protein. Technically this is true, however, the quality of that protein could be questionable if the quantity of a particular essential amino acid is too small. Soy products are a good example of this. Like all legumes soy is deficient in the two essential amino acids methionine and cysteine. And the commercial processing method used today also makes the very fragile amino acid lysine dysfunctional. So even though all the essential amino acids are present in the product, it is essentially unusable as a high quality, complete protein.
It is very important for everyone to consume high quality, complete proteins, and in enough quantity. Vegetarians have more difficulty accomplishing this because most vegetables, fruits, grains, nuts and seeds do not have all 8 essential amino acids, or they may have all of them but at levels too low to be effective.
If you are an ovo-lacto (eats eggs and dairy) vegetarian then you are getting complete proteins in the eggs and cheese that you consume. However if you are a vegan (one who avoids all animal-based foods) you need to achieve optimal nutrition by combining foods to make a complete protein.
Many people consume whole grains, nuts, seeds and legumes to get their proteins. The optimum ratios of protein, fats, vegetables and fruit you can find in the Mediterranean tipe Diet:
Sources of plant-based complete protein:
Vegetarian sources of animal-based complete protein:
Combining Plant-Based Foods To Get a Complete Protein
The chart below shows examples of three groups of foods that contain proteins. If you combine your proteins from any 2 of these 3 groups, you can get a complete protein:
Nuts & Seeds
Here are some examples: