When you think of protein, do you picture bodybuilders? It's true that protein is an essential nutrient to build lean muscle mass, but its primary role is as an all-purpose nutritional building block to maintain your health and vitality. Your entire body consists of protein; nerves, bones and muscle are all created and maintained with the help of protein. It is the principle component of your skin, hair, nails, blood, and internal organs.

Protein has about 4 calories per gram. While your body's primary fuel sources come from carbohydrates and fats, protein can step in and take that role when there are insufficient amounts of those macronutrients. When carbs and fats are adequately provided for in the diet, protein is used for tissue building and maintenance.

Some of the primary hormones are largely comprised protein components called amino acids. Insulin and other critical hormones are also of amino acids. They are responsible for metabolic rate, growth rate, and sexual development.

Enzymes are the catalysts for a myriad of chemical processes that take place in your body. They are also amino acids, protein. Enzymes are required to perform digestion, produce viral and bacterial antibodies, and a host of other necessary processes.

Your digestive system's enzymes break down large protein molecules, which are basically chains of amino acids, into each individual amino acid. These amino acids are reserved" by the body and used when we need the building blocks to create complex tissue.

Proteins are classified into two categories:

* Essential Amino Acids
* Non-Essential Amino Acids

"Non-essential amino acids" are not really "non-essential." The body needs them just as it does "essential" ones. However, they are called "nonessential" because the body can synthesize them itself. On the other hand, "essential" amino acids cannot be synthesized and must be gotten from the diet.

While it's true that the bodybuilding and fitness communities tout a fairly high consumption of protein per pound of bodyweight to be optimal, in fact, most nutritionists now teach that our dietary level of protein should be much lower. We should focus on "enough" protein, and you can, indeed, get "too much protein."

Your protein sources should come from lean meats, such as lean beef or skinless chicken, or fish. If you're a vegetarian, you can get ample protein just from high protein plant sources, such as beans and legumes. Even if you're not vegetarian, it's a good idea to include beans and legumes in your diet because of the soluble fiber they provide. They're also high in essential nutrients besides protein, like folic acid. It should also be noted that it is not at all true that plant or vegetarian sources of protein are inferior or "incomplete". Now we know that the body does not need a full compliment of amino acids in each meal to build tissue, and simply ingesting enough calories and enough of these types of foods is enough. That's where the concept of "amino acid pool" was developed.

In short, it's only of benefit to get a lot (or even all) of your protein from plant-based foods, and not hard at all. And give greens a try, too. They're chock full of nutrition and fiber (and after all, that's how a bull grows big and strong, with lots of greens, or grass).