Understanding Protein

Proteins are distinct from other macronutrients (carbohydrates, fats, and alcohol) in that they are comprised of chains of nitrogen-containing subunits called amino acids. All amino acids are important due to the fact that they are the primary source of dietary nitrogen (an essential element). However, some amino acids can be synthesized in the body from other materials and for this reason are not considered essential.

Of the 22 amino acids found in nature, eight are referred to as essential due to the fact that the body is unable to manufacture them at any point throughout the life cycle. These amino acids, aptly named essential amino acids (EAAs) must be obtained in substantial amounts and on a consistent basis from exogenous (foods or dietary supplements) to prevent deficiency.

Seven other amino acids are considered conditionally essential (CEAAs) because the body may have difficulty synthesizing them (or enough of them) under certain conditions such as illness, surgery, injury, extreme emotional stress, and/or intense physical activity.

The remaining amino acids can be produced as needed, provided the body has access to all the necessary raw materials (nitrogen, carbon, sulfur, etc.), and are therefore classified as nonessential amino acids (NEAAs).

Using these three groups of amino acids, the body polymerizes (links) elaborate chain-like molecules called proteins. Among other things, proteins function: (1) to maintain body structure (collagen, keratin, elastin), (2) in transport (hemoglobin, albumin), (3) to facilitate movement (actin, myosin), (4) in metabolism (numerous enzymes), (5) in immune functions (immunoglobulins), and (6) in regulation (various hormones and neurotransmitters).

More importantly, at least to athletes and bodybuilders, amino acids are the "building blocks" of lean muscle tissue.
EssentialConditionally EssentialNonessential
Amino AcidsAmino AcidsAmino Acids
LysineGlutamineAspartic Acid
PhenylalanineProlineGlutamic Acid

*Branched Chain Amino Acid

Why Athletes Need More Protein
The body's ability to synthesize these and thousands of other proteins is dependent upon the availability of all the amino acids at any given time. Unlike carbohydrate and fat, which are stored as glycogen and triglycerides respectively, the body maintains only a very small pool of amino acids. If one or more of the EAAs in this pool is low, the body is unable to complete synthesis of any of the proteins calling for this/these amino acids.

Think of amino acids as letters in the alphabet and intact proteins as words to help better understand the importance of having all the amino acids present when protein synthesis takes place. Using this analogy, one could easily imagine how difficult it would be to construct words, sentences, and paragraphs without letters. Similarly, the body uses amino acids to create over 100,000 different compounds in the body. Disturbingly, even short term EAA or CEAA deficiencies can stifle the important repair and rebuilding process associated with all healthy cells, especially growing muscle cells.

Luckily this scenario can be easily prevented with a well-balanced diet containing adequate amounts of high quality protein from a variety of sources. Current research indicates that hard training athletes require approximately one gram of protein per pound of bodyweight per day (1 g protein / lb of bodyweight / per day).
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