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Proteins- Compounds composed of atoms of carbon, hydrogen, oxygen, and nitrogen that are arranged as strands of amino acids.  Some amino acids also contain atoms of sulphur.  About 20% of our total body weight is protein.  Proteins come in many forms, enzymes, antibodies, hormones, transport vehicles, oxygen carriers, tendons, ligaments, scars, the cores of bones teeth and filaments of hair.

Diets high in animal proteins typically require an increase in calcium.  Such diets promote excess calcium excretion.  Excess protein may also create an increased demand for Vitamin B6 which the body uses to utilize the protein.

Functions of Protein- Provide growth and repair tissue.  Is vital in parts of the body (teeth and skin for example).  It also has regulatory roles in enzymes, hormones and antibodies, fluid balance, acid-base balance transportation.

Amino Acids- The building blocks of protein.  All amino acids have the same simple chemical backbone with an amine group (the nitrogen containing part) at one end and an acid group at the other end.  The side chains vary in complexity from a single hydrogen atom like that one glycine, to a complex ring structure.

The body can make about half of the amino acids from itself when it has the needed parts: nitrogen to form the amino group and backbone fragments, which are derived from carbohydrate or fat.

The distinction between essential and non-essential is not as clear cut as the list appears.  For example, cystenine and tyrosine normally are not essential because the body makes them from methionine and phenylaline.  However, if there are not enough of the precursors from which to make the cystenine and tyrosine, they must be supplied by the diet.

In general, amino acids from animal and soy proteins are the most easily absorbed (90 to 100%).  Amino acids from other legumes are considered the next best (80-90%) while grains and other plants very (70-90%).

Protein Synthesis – The process by which cells assemble amino acids into proteins.

Denaturation- A change in the shape of a protein brought about by heat, alcohol, aids, bases, salts of heavy metals, or other agents.  Denaturation is the first step in breakdown of the protein which is useful in the body for digestion.

In the first step of protein synthesis, each amino acid is hooked to the next.  A bond called a peptide bond is formed between the amino acid end of one and the acid end of the next.  Proteins are made of many amino acid units from several to many hundred.

Additional steps may be needed for the protein to become functional.  A mineral or vitamin may be needed to complete the unit and activate it, or several proteins may gather to form a functioning group. 

Enzymes- These are the hands-on workers in the production and processing of all substances needed by the body.  All enzymes are proteins and they are amont the most important parts in living things.  Enzymes are catalyst biological spark plugs that help chemical reactions take place.  The mystery of how an enzyme can be specific for a particular reaction is only partially understood.

Hormones- Chemical messengers in te body that are secreted by a variety of glands in response to altered conditions.  Each affects one or more target tissues or organs and elicit specific responses to restore normal conditions.  Hormones regulate overall body conditions such as the blood glucose level (the hormones insulin and glucagon) and the metabolic rate (thyroid hormone).

Antibodies- Large proteins of the blood and body fluids that are produced by one type of immune cell in response to invasion of the body by unfamiliar molecules.  Antibodies inactivate the foreign substances and so protect the body.  The foreign substances are called antigens.  Once the body has learned to make a particular antibody, it never forgets, and the next time it encounters that same antigen, it will be equipped to destroy it.

Transport Proteins- Proteins that carry nutrients and other molecules in body fluids.  Some transport proteins reside in cell membranes and act as “pumps” by picking up compounds so one one side of the membrane and releasing them on the other side as needed.

Leanest Meats - Flank steak, round steak, sirloin, tenderloin, extra lean ground beef, Canadian bacon, pork tenderloin, center loin and pork chops.

Summary of Protein Digestion and Absorption

Digestion begins with the mouth as the protein is crushed by the teeth and mixes with saliva.  Once the food is swallowed, stomach acids work to denature protein strands and activate stomach enzymes.  The enzyme pepsin breaks the protein strands into dipeptides, tripeptides and polypeptides.  A mucous coating on the stomach wall protects the stomach’s own protein from both the harsh acid and the protein digestion enzymes.

Next, the protein fragments leave the stomach nad move towards the small intestine.  The protein is split into free amino acids with the help of enzymes from the pancreas and small intestine.  Enzymes on the surface of the small intestinal cells break these peptides into amin acids, and they are absorbed through the microvilli of the small intestine into the blood.

Finally, the lare intestine carries any undigested protein residue out of the body.  In normal circumstances, all the protein is digested and absorbed.

Milk versus Whey

Whey protein is a naturally complete protein, meaning that it contains all of the essential amino acids required in the daily diet. It has the ideal combination of amino acids to help improve body composition and enhance athletic performance.

Whey protein is a supplement which is left overs from milk coagulates, and contains everything that is soluble from milk.  It is removed after cheese is processed, onve the fat is removed it can be processed for humans.  There are different varieties of whey: Concentrates, Isolates and Hydrolysates. 

Concentrates: Contain low level of fat and cholesterol but, in general, have higher levels of bioactive compounds, and carbohydrates in the form of lactose (ie. less quality).

Isolates: Are processed to remove the fat, and lactose, but are usually lower in bioactive compounds as well  (ie. high quality).

Hydrolysates: These are partially hydrolyzed whey proteins that, as a consequence, are more easily absorbed but cost more.  (ie. highest quality)

Milk is a translucent white liquid produced by the mammary glands of mammals.  It provides the primary source of nutrition for young mammals before they are able to digest other types of food.  The exact components of raw milk vary by species, but it contains significant amounts of saturated fat, protein and calcium as well as vitamin C.  Milk is primairly made up of (~80%) from casien.

An attractive property of the casein molecule is its ability to form a gel or clot in the stomach.  The ability to form this clot makes it very efficient in nutrient supply.  The clot is able to provide a sustained slow release of amino acids into the blood stream, sometimes lasting for several hours.  This provides better nitrogen retention and utilization by the body.