Macronutrients PDF

Macronutrients Eman Abdelrazek Elhelbawy Proffessor of clinical oncology and nuclear medicine Menofia University Clinical nutrition in health care Diploma Tanta Unversity  Objectives  Macronutrients  Carbohydrates  Protiens ...

Macronutrients Eman Abdelrazek Elhelbawy Proffessor of clinical oncology and nuclear medicine Menofia University Clinical nutrition in health care Diploma Tanta Unversity  Objectives  Macronutrients  Carbohydrates  Protiens  Fats  Water and hydration Macronutrients, or nutrients needed in large amounts, include carbohydrates, fats, proteins and water and are critical for cells, tissues, and organs. These macronutrients power cellular energy, prevent disease, and facilitate optimal body function. Carbohydrates Carbohydrates are macronutrients and are one of the three main ways by which our body obtains its energy. They are called carbohydrates as they comprise carbon, hydrogen and oxygen at their chemical level. Carbohydrates are essential nutrients which include sugars, fibers and starches. They are found in grains, vegetables, fruits and in milk and other dairy products. They are the basic food groups which play an important role in a healthy life. They are composed of organic carbon, hydrogen, and oxygen molecules and are found naturally in fruits, vegetables, legumes, grains, and dairy products. The end product of carbohydrate metabolismis a simple sugar; the three main ones involved in human nutrition are glucose, galactose, and fructose. Glucose, a simple sugar, provides energy to cells and is the preferred fuel for the brain and nervous system. It is a monosaccharide, which is a sugar molecule that cannot be further metabolized. Classification of Carbohydrates The carbohydrates are further classified into simple and complex which is mainly based on their chemical structure and degree of polymerization. Simple Carbohydrates (Monosaccharides, Disaccharides and Oligosaccharides) Simple carbohydrates have one or two sugar molecules. In simple carbohydrates, molecules are digested and converted quickly resulting in a rise in the blood sugar levels. They are abundantly found in milk products, beer, fruits, refined sugars, candies, etc. These carbohydrates are called empty calories, as they do not possess fiber, vitamins and minerals. Plants, being producers, synthesize glucose (C6H12O6) using raw materials like carbon dioxide and water in the presence of sunlight. This process of photosynthesis converts solar energy to chemical energy. Consumers feed on plants and harvest energy stored in the bonds of the compounds synthesized by plants. Monosaccharides Glucose is an example of a carbohydrate monomer or monosaccharide. Other examples of monosaccharides include mannose, galactose, fructose, etc. Disaccharides Two monosaccharides combine to form a disaccharide. Examples of carbohydrates having two monomers include- Sucrose, Lactose, Maltose, etc. Oligosaccharides Carbohydrates formed by the condensation of 2-9 monomers are called oligosaccharides. By this convention, trioses, pentoses, hexoses are all oligosaccharides. Complex Carbohydrates (Polysaccharides) Complex carbohydrates have two or more sugar molecules, hence they are referred to as starchy foods. In complex carbohydrates, molecules are digested and converted slowly compared to simple carbohydrates. They are abundantly found in lentils, beans, peanuts, potatoes, peas, corn, whole-grain bread, cereals, etc. Polysaccharides are complex carbohydrates formed by the polymerization of a large number of monomers. Examples of polysaccharides include starch, glycogen, cellulose, etc. Lipids are a general term for fats and lipoids and their derivatives. Fat is triglyceride, also known as triacylglycerol (TG); lipoids include phospholipids (PL), glycolipids; cholesterol (Ch) includes free cholesterol (FC) and cholesterol ester (CE). In normal people, the amount of lipids accounts for 25% of body weight, and most of them are stored in adipose tissue in the form of triglycerides. Lipoid is the basic structure of the tissue, called basic or fixed fat, accounting for 5% of the total lipid content. The lipids present in various tissues are body fats, and the body fat stores huge energy. When the body heat is insufficient, body fat can be used for energy consumption. A small number of lipids present in the blood circulation are blood lipids which are mainly phospholipids, triglycerides, cholesterol, free fatty acids, and trace amounts of fat-soluble vitamins and steroid hormones. Free fatty acids are mainly decomposed by TG in body fat and then enter the blood circulation. Lipids are insoluble in water, and lipids in plasma can only be transported to the body throughout the blood cycle by binding to proteins and becoming hydrophilic. Free fatty acids bind to albumin while the remaining lipids combine with globulin to form lipoproteins. Lipoproteins containing more TG are with low density, and those containing less TG have higher density. According to the density of lipoproteins, plasma lipoproteins can be divided into four categories: (1) chylomicrons (CM). (2) very low density lipoprotein (VLDL)’ (3) low density lipoprotein (LDL). (4) high density lipoprotein (HDL). After binding to lipids, proteins take part in transporting lipids in plasma, so they are called apolipoproteins. The small intestine is the most important place for fat digestion and absorption. The Fats reach the small intestine in the form of large globules. The liver releases bile juice to emulsify the fats, breaking down the large globules into smaller globules. The Role of Bile in Fat Digestion Bile salts, produced by the liver, help emulsify fats. Bile salts reduce the surface tension of fats and break them down into smaller globules. The gallbladder stores the bile and releases it into the small intestine as needed. Effect of Pancreatic Lipase The pancreas secretes pancreatic lipase, the key enzyme for fat digestion. Pancreatic lipase acts on the emulsified fat globules and breaks them down into smaller molecules. Pancreatic lipase is mainly secreted by pancreatic acinar cells and functions to digest the fat in the duodenum, including the classic pancreatic triglyceride lipase (PTL), pancreatic lipase-related protein 1 (PLRP1) and 2 (PLRP2), bile salt-stimulated lipase (BSSL) and pancreatic phospholipase A2 (PLA2), etc. PLRP2 is also expressed in lymphocytes and colonic epithelial cells, which are involved in the inflammatory response and regulating the intestinal flora. These important pancreatic lipases participant in the digestion of lipids (such as triglycerides, cholesterol, and phospholipids), so that dietary fat can be fully utilized. Proteins  Proteins are found in every cell and perform various functions in the human body. The digestion of proteins begins in the stomach with the enzyme pepsin and hydrochloric acid.  The acidic environment denatures the proteins, and the enzyme divides the protein into smaller polypeptides, which are linear organic molecules consisting of many amino acid residues bonded together in a chain.  The small intestine also releases digestive hormones, including secretin and cholecystokinin, which stimulate the enzymes to break down the proteins into individual amino acids.  Accessory organs release additional enzymes and contribute to the breaking of complex proteins into smaller individual amino acids, which are transported across the intestinal mucosa. In the final stages of metabolism, amino acids remain in the amino acid pool, a total number of essential amino acids and nonessential amino acids available for building proteins, which is regulated by the liver. Circulating amino acids recombine to form every protein required for maintenance and growth. In contrast, excess protein is converted to glucose or triglycerides depending on the body’s need for energy. Amino acids are classified as essential if they come from food and nonessential if the body can synthesize them. Amino acids are continually needed to replace normal cell breakdown. Each protein has a specific sequencing of amino acids; when one is missing, protein synthesis stops until the muscle breaks down to free up the needed amino acids for the amino acid pool. The intricate folding of the protein molecule is based on the function required. For example, the proteins in nails, when compared to those in the eyes, are very different in structure because the functions are highly diverse. protein myths have elevated this macronutrient to an extreme level. High-protein diets, protein powder, and amino acid supplements are popular as individuals pursue well-muscled bodies. Most adults require only 1–1.2 g of protein per kilogram of body weight daily. For example, a person who weighs 165 lb (75 kg), should consume 75–90 g of protein daily. Protein is not stockpiled in the body. A diet high in protein will not make for larger muscles or longer hair and nails, but an excessive amount of protein can contribute to weight gain. Unneeded protein is stripped of its amino group, the nitrogen is excreted in the urine, and the carbon remnant is converted to either glucose or triglyceride for use as energy. Proteins from animal sources provide the highest quality proteins or “complete proteins” because they contain all the essential amino acids. Meat, fish, poultry, and eggs are complete proteins. However, individuals following a plant-based diet can achieve complete proteins by eating various legumes, grains, and nuts. Interestingly, soy is the only legume classed as “complete” because it contains all the essential amino acids. However, it is less digestible than animal protein, as humans cannot digest cellulose in the plant cell structure. Hydration Function Water is the universal solvent; every cell, tissue, and organ requires water to transport essential substances. Molecules dissolve into the watery blood environment and move through the body, providing cellular support. Blood also carries breakdown products for elimination. Staying hydrated is essential to good health and can be accomplished by responding to thirst and A color chart indicates the hydration level of urine. A intentionally monitoring fluid intake. very pale color indicates overhydration, whereas darker colors indicate underhydration Water has zero calories and is readily available. Plain water is best; tea, coffee, and sodas also provide fluids but often contain caffeine and sugar. How much water or other fluids are needed daily depends on body weight, disease state, and activity level. According to the Academy of Nutrition and Dietetics, the recommended amount of water consumed per day is about 11.5 cups for women and 15.5 cups for men. This includes fluids consumed from both foods and beverages. Approximately 20% of this water comes from food consumption. THANK YOU