Proteins are also carriers or transporters. Some carriers help nutrients cross cell walls, others are in the body fluids and carry nutrients and other compounds throughout the body, for example the protein hemoglobin carries oxygen from the lungs to the body cells. Proteins help maintain the body’s fluid and electrolyte balance. By accepting and releasing hydrogen proteins act like buffers to help maintain the body’s acid-base balance. Antibodies are proteins that function to defend the body against disease. Proteins also function in blood clotting and vision, wound healing.
Even though protein has vital functions in the body, if glucose is limited the body can metabolize amino acids for energy. One gram of protein provides 4 calories. The body will break down body tissues in order to provide the amino acids for energy, which can lead to wasting of lean body tissue. The body is constantly breaking down and repairing body tissues, making hormones, enzymes and other body protein compounds. Therefore, the protein must be replaced by new protein.
For your body to use the proteins from the foods you eat, it must do two things. First, the body breaks down the proteins in the digestion process to amino acids. The cells lining our digestive tract absorb single amino acids or small chains of two or three amino acids, which are broken down in the intestinal wall cells. Second, the cells in the body take up those amino acids and rearrange them to build the body proteins it needs. One common misconception is to take enzyme supplements. Enzymes are proteins and the digestive enzymes will breakdown the enzyme into single amino acids, and it will not loner be an enzyme. Then the body will use these amino acids to build the proteins it needs, not necessarily will the original enzyme be reformed by the body.
We get dietary proteins from both animal and plant foods. Proteins from animal sources are called complete proteins, because they contain all the essential amino acids in amounts large enough to meet the body’s needs. Proteins from vegetable sources are called incomplete proteins, because they are low in one or more of the essential amino acids. Some plant proteins such as soy protein are complete.
Continues on next page…