8.5: Proteins (Amino Acids)

Our bodies need protein from the foods we eat to provide us with energy (calories) and to build, maintain, and repair, bones, muscles and skin. Protein is a component of every cell in the human body, found in almost all body fluids, and is important for many body processes, such as blood clotting, fluid balance, immune response, vision, and production of hormones, antibodies, and enzymes. Most Americans get the recommended amounts of protein to meet their needs.

Like Carbohydrates, proteins provide us with four calories of energy per gram consumed. Protein is found in both plant and animals foods. We commonly get proteins in our diet from meat, dairy products, nuts, and certain grains and beans.

Proteins are made up of amino acids. There are 20 different amino acids that that can be combined to make every type of protein in the body. Imagine each Amino Acid was a Lego piece and by combining various amino acids together you make different proteins. Of the 20 amino acids, nine of them are considered essential, meaning we need to bring them into our body through the food we eat. The other 11 amino acids are called non-essential because our body can produce them, so we don’t need to consume them in our diet. A protein that contains all nine essential amino acids is called a Complete Protein. Most complete proteins come from animal sources, such as dairy products, eggs, meats, poultry, seafood, and soy is a plant-based complete protein source. Incomplete proteins are either missing one or more of the nine essential proteins or do not contain enough of one of them. Most plant foods such as beans, grains, nuts, peas, seeds, and vegetables are incomplete protein sources. Foods can be combined together to provide all nine essential amino acids, this is called complementary proteins. For example, grains are low in the amino acid lysine, while beans and nuts (legumes) are low in the amino acid methionine. When grains and legumes are eaten together (such as rice and beans or peanut butter on whole wheat bread), they form a complete protein.

Tips for Consuming Protein

• The Daily Value for protein is 50 g per day. This is based on a 2,000 calorie daily diet—your Daily Value may be higher or lower depending on your calorie needs. Look at your food label to see whether the food you are eating is high or low in protein by looking at the %DV.
  • Note the total %DV for proteins which will help you meet the AMDR for proteins which is to consume between 10-35% of your calories from proteins.
• Choose a variety of protein, such as beans and peas, eggs, fat-free or 1% low-fat dairy products, lean meats and poultry, seafood, soy products, and unsalted nuts and seeds.
• Choose seafood and plant sources of protein (such as beans and peas, tofu and other soy products, and unsalted nuts and seeds) in place of some meats and poultry.
• Add beans and peas to salads, soups, and side dishes—or serve them as a main dish.
• Substitute fat-free or 1% low-fat dairy products and fortified plant-based beverages (such as soy, rice, and almond) for whole and 2% reduced-fat dairy products.
• Select fresh meats, poultry, and seafood, rather than processed varieties.
• Trim or drain fat from meats before or after cooking and remove poultry skin before eating.
• Try baking, broiling, grilling, or steaming. These cooking methods do not add extra fat

Your Food Label: Protein

Evaluate the proteins on your food label. What does the food label tell you about the protein you are consuming? Is this a high or low protein food? What types of protein are in the food item, plant or animal sources? Would you consider this to be a good source of protein? How much does this food item contribute to the AMDR for protein?