Probably no nutrition issue is of more concern to those interested in building muscle or increasing fitness than is the optimal amount of protein to consume. Although muscle tissue is composed of only 20 percent protein, protein is the nutrient most connected to increased muscle gains. To simplify it, when you exercise you break down muscle fibers, which are then repaired during rest. The body compensates for the imposed stress of exercise by causing the damaged muscle fibers to become thicker. This process involves muscle protein synthesis, and the raw material for that muscle protein synthesis are amino acids, the elemental form of protein. So it's true that protein is the most important nutrient for building muscle. Of course, protein is used for a lot of other things in the body other than for muscle building purposes. Besides muscle, the structural components of the body, such as connective tissue, are largely made of protein. Immune cells that protect against disease onset are proteins, as are digestive enzymes that break down food components, including protein foods. And let's not forget that certain hormones are nothing more than specific sequences of amino acids. This includes growth hormone, insulinlike growth factor-1 (IGF-1) and insulin. Thyroid hormone is a combination of the amino acid tyrosine along with the trace mineral iodine. When you add this up, it's no surprise that the word "protein" is derived from a saying "First in importance."
While no one denies the importance of protein in the diet, the major controversy related to protein is how much is needed for both health and muscle-building purposes. Protein is unique among the three major macronutrients (the others being carbohydrate and fat) because it alone contains nitrogen, about 16% in content. Although people often talk about protein needs, what the body really needs are amino acids. These are the most elemental form of protein, what results after food protein goes through the digestive process. Although there are 22 amino acids active in human physiology, only nine of them are considered essential. They are called "essential" because they must be consumed in the diet. The other amino acids, often called "non-essential" can be produced from other amino acids and substances in the body. But to say that they are useless would be incorrect. While only the nine essential amino acids (EAA) are required to build muscle, meaning that if you consumed only those EAAs you wouldn't need any other amino acids, the non-essential amino acids provide some useful health benefits. In the non-essential category, glutamine is useful for maintaining gut health and the need for it increases under high stress conditions, where the body cannot synthesize enough glutamine to meet an increased need imposed by stress.
One often overlooked fact about EAAs is that they must be all present at the same time for maximal muscle protein synthesis to proceed. If even one of them is . . .