Chapter 14: Proteins and Amino Acids PDF

FSHN 285 Chapter Fourteen Proteins and Amino Acids The term protein is derived from the Greek word protos, meaning first. The average intake of protein by adults in The United States is 88 grams per day. The Recommended Dietary Allowance (RDA)...

FSHN 285 Chapter Fourteen Proteins and Amino Acids The term protein is derived from the Greek word protos, meaning first. The average intake of protein by adults in The United States is 88 grams per day. The Recommended Dietary Allowance (RDA) is based on an individual’s body size (0.8 grams of protein/kilogram of body weight). Based on this, the RDA for a 180 lb person is 65 grams of protein per day. Now calculate your personal protein needs:.8 grams protein per kg of your body weight. Tip: Divide your weight in pounds by 2.2 to make your weight into kg. Your personal protein needs: 39.6 grams per day. Protein intake can also be assessed using the Acceptable Macronutrient Distribution Range (AMDR) for protein (10 to 35% of total calories). When considered from this context, the average U.S. intake of protein is 16% of total calories. We will discuss protein needs for athletes in chapter 26. Functions of Protein: Proteins perform structural and functional roles in the body. They are an integral component of skeletal muscle, bone, connective tissues (skin, collagen, and cartilage), organs (such as heart, liver, and kidneys), red blood cells and hemoglobin, hair, and fingernails. Proteins are the basic substances that make up thousands of enzymes in the human body; they are a major component of hormones such as insulin and growth hormone. Proteins play key roles in the repair of body tissue by serving as substances-such as fibrin-that help blood clot and replace damaged tissue proteins. Protein can also serve as an energy source (4 calories per gram) when needed. Protein is unlike carbohydrates and fat in that it contains nitrogen. It also does not have a temporary storage form in the body, similar to how excess glucose from carbohydrates can be stored as glycogen. This means excess energy from protein intake can lead to protein being stored as body fat. Nitrogen Balance: All protein in the body is constantly being turned over or broken down and rebuilt. This process helps maintain protein tissues and keeps them in optimal condition. Protein intake is estimated based on the nitrogen content of protein consumed. The nitrogen content of protein is estimated as 16% of the weight of protein consumed. Nitrogen excretion is assessed as the amount of nitrogen excreted in the form of urea. Nitrogen balance is measured as the difference between nitrogen intake and nitrogen excreted. List times in life that negative nitrogen balance occurs: Lower intake of protein than the body is utilizing Undernutrition and Fasting Burns and other serious injuries Fever and other illnesses List times in life that positive nitrogen balance occurs: Some proteins are being retained and instead being used to build up body protein tissue Growth Pregnancy and Breastfeeding Revorcy from a illness or injury Amino Acids: Amino acids are the building blocks of protein and differ from carbohydrates and fat in that they contain nitrogen. How many amino acids are there? 20 There are 9 essential amino acids and 11 nonessential amino acids. Why are essential amino acids considered “essential”? The body can’t produce or production can’t supply an adequate amount. Need in your diet Why are nonessential amino acids considered “nonessential”? No need to get them through diet since your body can produce an adequate amount. However there are outliers such as if you are suffering that prevent your body from producing adequate amounts, you need to incorporate nonessential amino acids in your diet. Can foods contain both essential and nonessential amino acids? Proteins in food contain both Amino acids cannot be stored very long in the body, so we need a fresh supply of essential amino acids daily. Define DNA: Cells that contain genetic information and that they are bonded through hydrogen bonds. They also direct protein synthesis. Amino Acids and Protein Structure How do primary proteins differ from secondary, tertiary and quaternary protein structures? Primary proteins are linked amino acids, think of it like a long pearl though a line. Secondary structure can be seen in folded chains of amino acids or a helix. Tertiary structure is a 3-dimensional structure and contains larger proteins. Think of it as a crumbled telephone cord. Lastly, for a quaternary structure you need 2 or more tertiary structures. This structure is the largest and has multiple linked amino acids so they perform a certain function. Protein Quality: The ability of dietary protein tissue construction and maintenance in the body depends on the availability of essential amino acids. Dietary proteins that contain all essential amino acids in the amounts needed to support protein synthesis (formation) by the body are referred to as high quality or complete proteins. Complete protein food sources: They come from animal sources such as mea, milk, fish and eggs. Incomplete proteins are protein sources that are deficient in one or more essential amino acids. Food sources of incomplete proteins: They from plant based products such as nuts, seeds, gains, and legumes Which plant protein is a complete protein for adults? soybeans Which animal derived protein is an incomplete protein? gelatin Vegetarian Diets: How does one get complete proteins if they are vegetarian? By combining incomplete proteins they are able to get their essential amino acids. However you include a variety of plant protein sources. Amino Acid Supplements: Are they safe? No they are not safe when a large consumption occurs. Risks of taking in too many amino acids: It disturbs the protein synthesis to function properly. The biggest users of amino acid supplements are: Athletes, since they believe it will increase their muscle mass and strength. What is Melatonin and how is it used? So that you are able to sleep peacefully. Building Muscle Mass and Strength: Current research indicates that you may be able to enhance muscle mass by consuming 20 grams of high-quality protein immediately following resistance exercise workouts. Older adults may need 40 grams of high-quality protein. Examples of high quality protein foods: 1. Skim Milk 2. Lean Meat 3. Fish 4. Egg white 5. Beans and rice Protein intakes over 20 grams following exercise may not offer additional benefits in young adults. Food as a source of protein: Approximately 2/3 of the protein consumed by Americans comes from meats, dairy products and other animal products. Higher intakes of animal-based protein are associated with diets higher in saturated fats and lower in dietary fiber in comparison to diets that derive more protein from plant sources. Why is this? Fiber mostly comes from plant based products and contains little to no amount of saturated fat while generally protein from animals prices are higher in saturated fat and contain no fibers. Using page 181 as a reference, how many grams of protein are in each of these meals? 3 ounces tuna fish in a sandwich with 2 slices of whole wheat bread, and 1 cup of low fat yogurt. 41 grams. 1 cup oatmeal with 1 cup skim milk. 15 grams 1 tablespoon peanut butter on 1 slice whole wheat bread with 1 cup 2% milk. 14 grams. Protein Deficiency: Who gets protein deficient? When it occurs in children it decreases growth and if it affects adults you will lose muscle mass and strength. What is kwashiorkor: It is a form of malnutrition due to a severe lack of energy specifically on protein. How Much Protein is Too Much? Consumption of 35% of total calories from protein is considered too high. Consumption of this level of protein is related to gastrointestinal issues like nausea and diarrhea. High-protein diets have been implemented in the development of: 1. Kidney Stones 2. Cancer 3. Heart Disease