Clinical Nutrition: Protein & Lipids Lecture PDF

Clinical Nutrition Protein and Lipids BY Dr/Shimaa Abd EL-Rahim Protein Metabolism and deamination Function Classification Food Source Protein excess Protein Deficiency  Composition Like carbohydrates and fats, proteins contain ca...

Clinical Nutrition Protein and Lipids BY Dr/Shimaa Abd EL-Rahim Protein Metabolism and deamination Function Classification Food Source Protein excess Protein Deficiency  Composition Like carbohydrates and fats, proteins contain carbon, hydrogen, and oxygen, but in different proportions. In addition, and most important, they are the only nutrient group that contains nitrogen.  Pathways for protein metabolism Three important protein pathways: 1- Protein Turnover (protein synthesis and breakdown) 2- Amino acid catabolism and deamination 3-Transamination 1- Protein Turnover Two independent processes: Protein synthesis (putting aminoacids together into new protein structure) Protein breakdown (breaking down proteins into aminoacids units) The liver most amino acids go to the liver then they enter the blood stream and become part of (plasma pool of amino acids) that used to produce important molecules such as: enzymes hormones neurotransmitters antibodies transport protiens (carrier protein, lipoprotein) muscle proteins skeletal and connective tissues (bone, tendons,ligaments, cartilage)  IF our body needs energy and no other nutrients are easily available it can breake down to either help create other nutrients such as: a. glucose b. fatty acids c. cholesterol d. or keton bodies e. or to help regenerate ATP Protein turnover depends on nutritional intake exercise habits health and illness stress hormonal status genetic programming 2- Transamination Tansfer of Amino Groups from one aminoacids to ketoacids which results in the formation of a new aminoacid and a new keto acid Significance of Transamination : synthesis of nonessential aminoacid 3- Amino acid Catabolism and deamination When amino acids are needed to form non- protein compounds or to transfer energy to ATP,these nitogen groups must be eleminated this process of nitrogen removal is called deamination when amine groups break away from the aminoacids, they form ammonia Ammonia is very toxic to human convert it to a nontoxic chemical urea that can safely diffuse in the blood and for the kidneys to filter out and be excreted in the urine The remaining parts are converted to carbohydrate or fat and stored as glycogen or adipose tissue.  Function of protein The primary function of proteins is to build and repair body tissues.(proteins form the building blocks of muscles, blood, and skin—in fact, of most body structures) Proteins are important components of hormones and enzymes that are essential for the regulation of metabolism and digestion. Proteins also are essential for the development of antibodies and, consequently, for a healthy immune system.  Function of protein Proteins help maintain fluid and electrolyte balances in the body and thus prevent edema (abnormal retention of body fluids). As Acid-Base Regulators Proteins also help to maintain the balance between acids and bases within the body fluids. Proteins can provide energy if and when the supply of carbohydrates and fats in the diet is insufficient (In general, they are more expensive than carbohydrates, and most of the complete proteins also contain saturated fats and cholesterol)  Proteins are the basic material of everybody cell. An adequate supply of proteins in the daily diet is essential for normal growth and development and for the maintenance of health.  CLASSIFICATION The classification and quality of a protein depends on the number and types of amino acids it contains. There are 20 amino acids, Nine amino acids cannot be synthesized in the body and, therefore, must be present in the diet in order for protein synthesis to occur. Eleven amino acids can be synthesized in the body itself and hence do not necessarily need to be acquired through diet.  Complete proteins : Essential amino acids are necessary for normal growth and development and must be provided in the diet. Proteins containing all the essential amino acids are of high biologic value; these proteins are called complete proteins and are extremely bioavailable. (ability of a nutrient to be readily absorbed and used by the body)  Incomplete protein Incomplete proteins are those that lack one or more of the essential amino acids. Incomplete proteins cannot build tissue without the help of other proteins.  Complementary proteins Incomplete proteins that when combined provide all essential amino acids The value of each is increased when it is eaten in combination with another incomplete protein, not necessarily at the same meal but during the same day. In this way, one incomplete protein food can provide the essential amino acids the other lacks. The combination may thereby provide all the essential amino acids. When this occurs, the proteins are called complementary proteins. FOOD SOURCES The animal food sources provide the highest quality of complete proteins. They include meats, fish, poultry, eggs, milk, and cheese. Despite the high biologic value of proteins from animal food sources, they also provide saturated fats and cholesterol  Gelatin is the only protein from an animal source that is an incomplete protein. FOOD SOURCES Proteins found in plant foods are incomplete proteins and are of a lower biologic quality than those found in animal foods. Even so, plant foods are important sources of protein. Examples of plant foods containing protein are corn, grains, nuts, sunflower seeds, sesame seeds, and legumes.  FOOD SOURCES Meat alternatives (analogues) made from soybeans contain soy protein and other ingredients mixed together to simulate various kinds of meat. Meat alternatives may be canned, dried, or frozen. Analogues are excellent sources of protein, iron, and B vitamins.  DIETARY REQUIREMENTS One’s protein requirement is determined by size, age, sex, and physical and emotional conditions. A growing child, a pregnant woman, or a woman who is breastfeeding needs more protein for each pound of body weight than the average adult Extra proteins are usually required after surgery, severe burns, or during infections in order to replace lost tissue and to manufacture antibodies.  NITROGEN BALANCE This occurs when nitrogen intake equals the amount of nitrogen excreted Positive nitrogen balance exists when nitrogen intake exceeds the amount excreted. This indicates that new tissue is being formed, and it occurs during pregnancy, during children’s growing years, when athletes develop additional muscle tissue. Negative nitrogen balance indicates that protein is being lost. It may be caused by fevers, injury, surgery, burns, starvation, or immobilization.  DIETARY REQUIREMENTS The National Research Council of the National Academy of Sciences con siders the average adult’s daily requirement to be 0.8 gram of protein for each kilogram of body weight. e.g: 55 g of protein per day for 68 Kg person the National Research Council recommends that protein intake represent no more than 15% to 20% of one’s daily calorie intake  Protein Excess There are a number of reasons why this should be avoided 1-The saturated fats and cholesterol common to complete protein foods may contribute to heart disease and provide more calories than are desirable. 2-Some studies seem to indicate a connection between long- term high- protein diets and colon cancer and high calcium excretion. 3-People who eat excessive amounts of protein-rich foods may ignore the also essential fruits and vegetables. 4-excess protein intake may put more demands on the liver and the kidneys.  Protein Deficiency When people are unable to obtain an adequate supply of protein for an extended period, muscle wasting will occur, and arms and legs become very thin. Albumin (protein in blood plasma) deficiency will cause edema, resulting in an extremely swollen appearance. People may lose appetite, strength, and weight, and wounds may heal very slowly. Patients suffering from edema become lethargic and depressed.  PROTEIN AND AMINO ACID SUPPLEMENTS Protein and amino acid supplements are taken for a number of reasons, such as “bulking up “by athletes, growing fingernails, and sparing body protein in weight loss. In weight lifting, not protein bars or protein supplements, that builds muscles. High-quality protein foods are more bioavailable than expensive supplements. Single amino acids can be harmful to the body and never occur naturally in food. The body was designed to handle food, not supplements (Real food approach).  Proteins Supplements (protein powder) 1-Whey 2-Casein 3-Milk protein blend 4- Branched-chain (BCAA) supplements (particularly leucine) are good options for clients restricting energy intake, training fasted, and/or needing some extra peri-workout and /or post-workout recovery. 5-Lysine supplement can reduce cold sore severity, frequency, and healing time Lipids Composition and categories Metabolisim and Elimination Functions Classification Food source Sterol Lipoproteins  Composition: Fats contain Carbon, Hydrogen, Oxygen Lipids are organic compounds Lipids are soluble in fat Categories of Lipids: 1. Triglycerides 2. Phospholipids 3. Sterols Triglycerides " Fats" Triglycerides “Fats” Energy Yield: Fats provide 9 Calories/gram. –Fats are the only type of lipid that the body can convert to ATP or produce energy from. –Fats are the most Calorically Dense energy producing nutrient.  Metabolism and Elimination The liver controls fat metabolism. It hydrolyzes triglycerides and forms new ones from this hydrolysis as needed. Ultimately, the metabolism of fats occurs in the cells, where fatty acids are broken down to carbon dioxide and water, releasing energy. The portion of fat that is not needed for immediate use is stored as adipose tissue. Carbon dioxide and water are by-products that are used or removed from the body by the circulatory, respiratory, and excretory systems.  Function of fats They contain essential fatty acids and act as carriers for fat-soluble vitamins A, D, E, and K. The fat stored in body tissues provides energy when one cannot eat, as may occur during some illness and after abdominal surgery. Adipose (fatty) tissue protects organs and bones from injury by serving as protective padding and support. Body fat also serves as insulation from cold. In addition, fats provide a feeling of satiety (satisfaction) after meals. This is due partly to the flavor fats give other foods and partly to their slow rate of digestion, which delays hunger. They provide the structure of our plasma membranes  Fatty Acids Categories Dietary fats are defined by the composition of the fatty acids in the triglyceride. 1. Saturated fat food sources are comprised of mostly saturated fatty acids (SFAs). 2. Monounsaturated fat food sources are comprised mostly of monounsaturated fatty acids (MUFAs). 3. Polyunsaturated fat food sources are comprised mostly of polyunsaturated fatty acids (PUFAs). Classification of fatty acids Monounsaturated Fats Have 1 double bond in the carbon chain Are healthy Examples of foods containing monounsaturated fats are olive oil, peanut oil, canola oil, avocados, and cashew nuts. Research indicates that monounsaturated fats lower the amount of low-density lipoprotein (LDL) (“bad cholesterol”) in the blood, but only when they replace saturated fats in one’s diet. They have no effect on high-density lipoproteins (HDLs) (“good cholesterol”). It is recommended that one consume 15% of total daily calories as monounsaturated fats  Polyunsaturated Fats Have >1 double bond in the carbon chain. Some are essential for the body. Are found in plant oils like corn, cottonseed, safflower, and sunflower oil. Are liquid at room temperature. Too much can promote cancer. The two major fatty acids are the omega-3 and omega-6 fatty acids.  Omega- 3 Omega-3 fatty acids have been reported to help lower the risk of heart disease. Heart attack survivor who took a 1- gram capsule of omega 3 fates every day for three years were less likely to have a repeat heart attack, stroke, or die of sudden death than those took a placebo Research on the different types of fats has spot lighted the beneficial effects of the omega-3 polyunsaturated fatty acids in reducing the risks of heart disease and stroke. Regular consumption of omega-3 fatty acids helps to prevent blood clots, protect against irregular heartbeats, and lower blood pressure, especially in people with hypertension or atherosclerosis. (Flax seed oil - Fish oil)  Omega-6-fats Omega-6- fats are also healthy unsaturated fats There are four types of omega-6-fats LA (Linoleic acid) ARA (Arachiodonic acid) GLA (Gamma lionoleic) CLA (conjugated linoleic acid ) Omega-6 fats play an important role in regulating our genes and promoting immune health and blood clotting , also help with symptoms of rheumatoid arthritis and dermatitis.  Omega-6/Omega-3 ratio A balanced ratio of omega-6/omega-3 fatty acids is important for health and in the perevention of CHD and possibly other chronic diseases. A target of omega-6/omega-3 fatty acid ratio of 1:1 to 2:1 appears to be consistent with studies on evolutionary aspects of diet, neurodevelopment and genetics. Whether an omega-6/omega-3 ratio of 3:1 to 4:1 could prevent the pathogenesis of many diseases induced by today’s Western diets.  Saturated Fatty Acids Have 0 double bonds between the carbons. Are found in animal products, hydrogenated vegetable fats, & tropical oils (palm & coconut oil). Are solid at room temperature & unhealthy.  Trans-Fatty Acids Are produced when hydrogen atoms are added to monounsaturated or polyunsaturated fats to produce a semisolid product like margarine. The major source of TFAs in the diet is from baked goods and foods eaten in restaurants. TFAs raise LDLs and total cholesterol.  Sterol Cholesterol is a sterol , It is not a true fat but a fatlike substance that exists in animal foods and body cells. It does not exist in plant foods. Cholesterol is essential for the synthesis of bile, sex hormones, cortisone, and vitamin D and is needed by every cell in the body. The body manufactures 800 to 1,000 mg of cholesterol a day in the liver. Cholesterol’s harmful effects in the body occur when it forms deposits in the artery walls. These deposits lead to atherosclerosis, a disease that causes heart attacks and strokes.  Cholesterol is a common constituent (part) of one’s daily diet because it is found so abundantly in egg yolk, fatty meats, shellfish, butter, cream, cheese, whole milk, and organ meats (liver, kidneys, brains, sweetbreads) It is considered advisable that blood cholesterol levels not exceed 200 mg/dl (200 milligrams of cholesterol per 1 deciliter of blood). Cholesterol’s harmful effects in the body occur when it forms deposits in the artery walls. These deposits lead to atherosclerosis, a disease that causes heart at tacks and strokes.  Lipoproteins Fats are insoluble in water, which is the main component of blood. Therefore, special carriers must be provided for the fats to be absorbed and transported by the blood to body cells. Lipoproteins are classified according to their mobility and density as: 1- Chylomicrons, 2- Very-low-density lipoproteins (VLDLs), 3- Low-density lipoproteins (LDLs), 4- High-density lipoproteins (HDLs),  Chylomicrons Chylomicrons are the first lipoprotein identified after eating. They are the largest lipoproteins and the lightest in weight. They are composed of 80% to 90% triglycerides. Lipoprotein lipase acts to break down the triglycerides into free fatty acids and glycerol. Without this enzyme, fat could not get into the cells.  Low-density lipoproteins Low-density lipoproteins are approximately 45% cholesterol with few triglycerides. They carry most of the blood cholesterol from the liver to the cells. Elevated blood levels greater than 130 mg/dl of LDL are thought to be contributing factors in atherosclerosis. Low-density lipoprotein is sometimes termed bad cholesterol.  High-density lipoproteins High-density lipoproteins carry cholesterol from the cells to the liver for eventual excretion. The level at which low HDL becomes a major risk factor for heart disease has been set at 40 mg/dl. Research indicates that an HDL level of 60 mg/dl or more is considered protective against heart disease. High-density lipoproteins are sometimes called good cholesterol. Exercising, maintaining a desirable weight, and giving up smoking are all ways to increase one’s HDL.