Nutrition 101: Protein

Protein is an essential nutrient that has many functions in the body, including:

• Growth and maintenance. Protein is needed in building, repairing, and maintaining body cells and tissues. Our bodies are in a constant state of turnover or remodeling. Protein is the building block for that remodel. Higher levels of protein are need at times of rapid growth such as childhood, teenage years, and pregnancy.
• Immunity. Protein is used to build antibodies, blood cells, immune cells, and other substances that are needed to protect the body fight infections, allergens, bacteria, viruses, and other things that may cause harm.
• Acid Base Balance. The body maintains a balance between acidity and alkalinity. Various body systems are used to maintain an appropriate balance. Proteins (amino acids) are used a buffers in the blood to help keep the body in acid base balance.
• Blood Clotting. Proteins are used along with other mechanism to clot blood after injury.
• Enzymes, hormones, and compounds are built by stringing together amino acids, the building blocks of proteins.
• Transport. Protein are used within the body to carry vitamins, minerals, fats, and other substances.
• Fluid balance. Fluid is moved through the body from blood stream, cells, and spaces to achieve fluid balance. Proteins are part of the process to keep fluid balance. Edema/swelling is one example of what can happen with fluid imbalance.

Providing energy. In addition to the above, protein is an energy source for the body. Protein has 4 kcals/gram. Protein has so many other functions, is good to consumer carbohydrates and fats in addition to proteins, so protein can complete all the many functions in which its involved.

Amino acids are the building blocks of proteins. There are 20 amino acids, 9 of them are essential, meaning you need to consume them. Amino acids are linked together to create different proteins. The order the amino acids are linked determine what protein is created. For example, one order creates insulin, while another order of amino acids creates hemoglobin. There are thousands of proteins in your body built from 20 amino acids. All amino acids have the same backbone with an amine and acid group, the side chains are different for each amino acid.

The protein RDA (how much you need) for adults is 0.8 g pro/kg body weight -- less than many think. For a 150 pound person that is 54 grams of protein each day. To put that amount in perspective -- 8 oz of milk has 8 grams of protein, ½ cup rice has 3 grams of protein, 1 ounce of meat has 7 grams of protein, and ½ cup vegetables has 2 grams of protein. Most healthy adult Americans consume enough protein.

Protein is found in both animal and plant foods. Animal products such as meats, eggs, and dairy are high quality proteins. High quality protein supply amino acids in proportion to the body’s needs. Plant products such as legumes (beans), grains, and vegetables are lower quality proteins, because they lack or are lower in some amino acids. You can meet your protein needs with animal or plant foods. Choosing a variety of foods helps ensure your protein intake is adequate.