Protein Nutrition Guide

Proteins are macronutrients made up of a structure called an amino acid. There are a total of 20 different amino acids that come together in different combinations to make different proteins. The body can successfully make some of the amino acids, but others must be obtained in the diet. Amino acids that cannot be made by the body are called essential amino acids. There are nine essential amino acids and 11 non-essential amino acids.

Types of Protein

Proteins are categorized based on their amino acid structure. Proteins that contain all of the essential amino acids are referred to as complete proteins. These proteins include meat, poultry, fish, eggs, milk and cheese. Proteins that contain low amounts of one or more of the essential amino acids are called incomplete proteins. These proteins must be paired with other proteins, called complementary proteins, in order to make a complete protein source. Some examples are beans and rice.

Functions

Proteins are essential for various aspects of body functioning. Proteins, such as collagen and connective tissue, provide structure and support. Protein allows wound healing and regeneration of skin cells. In order to function properly, the body undergoes a number of chemical reactions every day. In order for these chemical reactions to take place, the body must contain a structure called an enzyme. According to "Nutrition and You" by Joan Salge Blake, most enzymes are proteins. Proteins also aid in the body's pH balance, fluid balance, transportation of important nutrients and immune system function. When needed, protein also provides the body with energy.

Daily Recommendations

Protein needs vary based on specific age, sex and activity level. The Food and Nutrition Board, which is a subgroup of the Institute of Medicine, recommends that protein intake should be a minimum of 0.8 g of protein per kilogram of body weight. Another guideline is that 10 to 35 percent of daily calories should come from protein.

Sources

According to the Centers for Disease Control and Prevention, most Americans consume over the recommended amount of protein every day. Animal sources of protein include meats, poultry, fish, eggs and milk products. Vegetable sources of protein include legumes, tofu, nuts, seeds, grains and some fruits and vegetables.

Considerations

Excess consumption of animal proteins can contribute a significant amount of saturated fat in the diet. Saturated fat can lead to narrowed arteries and contribute to heart disease. A proper balance of animal protein and vegetable protein is important in maintaining a healthy diet. "Nutrition and You" by Joan Salge Blake also notes that a high-protein diet can cause kidney stones and lead to osteoporosis.