Functions of Carbohydrates, Vitamins, Fats, Minerals, Protein and Water - Coursework Example

Functions of Carbohydrates, Vitamins, Fats, Minerals, Protein and Water Foods are commonly defined as substances “which when taken into the body, serve to nourish or build up the tissues or to supply heat”. The major categories include three type of substances that provide calories: carbohydrates, fats, and proteins; the remaining three are vitamins, minerals, and water, which does not nourish or supply heat but performs a variety of other useful functions. Foods with caloric value The calorie foods are oxidized to supply energy and heat in much the same way that gasoline fuels an automobile, but each of the three foods in this category also provide for other essential needs. Carbohydrates Carbohydrates in the form of sugars and starches usually provide approximately 50% of the body’s energy needs. The simple sugar, glucose, is the form of most commonly used; it is normally obtained as a result of digestion of such disaccharides (double sugars) as a source of cane sugar, maltose from cereal grains or from polysaccharides The glucose level of the blood is stabilized by storage of surplus amounts of glycogen (body starch), and their subsequent reconversion and release at a later time when blood levels again become low. Fructose and galactose are two other simple sugars that may be utilized directly for energy production; Carbohydrates contain three elements: carbon, oxygen and nitrogen; their relatively high oxygen content enables them to oxidize cleanly, yielding only carbondioxide and waste product, thus making them a very efficient energy source. Although caloric needs may also be met by fats and proteins, a minimum amount of carbohydrates is essential for safe metabolism of fats. Fats Fats reduced to 25% or less, is the minimum amount which is needed for good health. One of its most valuable functions is the transport of the fat soluble vitamins A and D which are essential to life itself. A moderate amount of fat in one’s diet can increase and maintain the feeling of satiety or satisfaction following a meal because it slows the rate at which food is moved out of the stomach. The relatively high carbon and hydrogen content of fat makes it highly concentrated source of fuel, a dietary feature that is sometimes useful during cold weather when caloric needs are high. A moderate amount of stored fat is also useful as a means of insulation against cold and as a protection for certain vital organs such as kidneys. Proteins Proteins contain nitrogen and sulphur, in addition to carbon, hydrogen and oxygen as in carbohydrates and fats. Their molecular structure is quite complex and consists of numerous smaller components termed amino acids. Although the body can synthesize many of the 23 amino acids that are known to exists, 8 of these essential components cannot be synthesized and must be obtained from one’s diet. Virtually, all animal sources of protein such as meat, eggs, and milk, are termed complete proteins because they contain all of 8 of the essential ones. Peanuts, soyabeans, and cereal grains are examples of good vegetable sources of proteins; however, none of these are complete in themselves. A combination of plant proteins is needed to obtain all the essential amino acids. These components cannot be stored in the body in the appreciable amount; therefore, it is usually recommended that some form of animal protein be included with every meal. The various amino acids are used for synthesis of proteins used in the formation and replacement of body tissue and for other purposes such as formation of needed enzymes. Foods without caloric value Water, certain minerals, and vitamins are absolutely essential to the physiological processes of the body. Although these nutrients are not oxidated to supply energy, neither energy production nor any other vital function is possible without them. Water The water reserves of the body provide such a short margin of safety that a lack of water can jeopardize one’s life within a week’s time. This near universal solvent facilitates countless vital chemical reactions and constitiutes the principal medium for the transport of foods, wastes and regulatory secretions throughout the body. The bulk of the human blood supply is composed of water and the constant circulation of this substance is essential to the maintainence of body temperature within its necessary narrow range. Another vital factor in temperature regulation is the release and subsequent evaporation of water on the surface of the skin in the form of perspiration. The highly variable demands that environmental and exercise factor place on this regulatory task cause daily water needs to fluctuate widely. Fortunately, the normal thirst mechanism provides a simple and effective guide to intake under any but the most abnormal conditions. Minerals Although they are needed in small amounts, 14 different minerals are known to be essential to good health. Iron is needed to form hemoglobin for oxygen transport and also for the utilization of oxygen in tissue respiration, as are zinc and chromium. Sulphur is required for the synthesis of many important proteins, and iodine is necessary for the formation of thyroid hormones, which in turn regulate the general metabolic processes of the body. Even the relatively undramatic regulation of body fluids by such minerals as sodium, potassium, and magnesium is essential to life. Many essential minerals are retained indefinitely and recycled; thus a few millionths of an ounce often fills the daily need for these trace elements. Calcium and phosphorus are exceptions in that they are not normally needed in substantial amounts by growing children, and expectant and nursing mothers, for bone and teeth formation; this need is readily met by sufficient milk and dairy products. Vitamins At present 13 vitamins are known to be essential, and search still continues for more of these rather dramatic organic compounds, which provide direct energy, form no part of body structure, yet are vital to the life of the individual. The functions of vitamins are as complex as they are essential. For most part they tend to act as catalysts and regulators of chemical activity. Riboflavin, one of the B complex group, plays a direct role in respiratory cycle that makes energy available, and its light sensitive qualities also make it important to the proper functioning of the retina in providing for good vision; however, most vitamins tend to act indirectly (Read and Walter 1973). Active Riboflavin is a Flavin Mononucleotide (FMN) or Flavin Adenine Dinucleotide (FAD). FMN and FAD serve as prosthetic groups of oxidoreductase enzymes. These enzymes are known as Flavoproteins. The prosthetic groups are usually Flavoprotein enzymes and are represented by several important oxidoreductases in mammalian metabolism, eg, α-aminoacid oxidase in aminoacid deamination, xanthine oxidase in purine degradation and aldehyde dehydrogenase in the degradation of aldehydes (Murray, 1996). The simple increase of antihemmorrhagic vitamin K in the blood will not reduce its clotting time, but this substance will aid the synthesizing of prothrombin - a substance necessary to control of bleeding. Vitamin D does not form any part of the bony structure of the body, but it activates phosphate metabolism, which in turn contribute to the disposition of calcium, the principal structural component. Folic acid, another member of the B complex group, aids in the synthesis of purine and pyrimidine compounds, which are essential to the formation of nucleoproteins; a deficiency of this vitamin is manifested first in the form of anemia due to the interference with red blood cell production. Significant quantitities of this food element are also synthesized and made available by bacteria that commonly reside in the intestine (Read and Walter, 1973). Active niacin is Nicotinamide Adenine Dinucleotide (NAD+) and Nicotinamide Adenine Dinucleotide Phosphate (NADP+). NAD+ and NADP+ are coenzymes for many oxidoreductase enzymes. Active vitamin B6 is pyridoxal phosphate. Pyridoxal phosphate is the coenzyme of several enzymes of mammalian metabolism. Pyridoxal phosphate also functions in glycogenolysis. Biotin functions as a component of specific multi subunit enzymes that catalyse carboxylase reactions. The Active vitamin B12 coenzymes are methyl cobalamine and deoxy adenosyl-cobalamine. Deoxy adenosyl-cobalamine is the coenzyme for the conversion of methyl malonyl-CoA to Succinyl CoA. This is the key reaction in the pathway of conversion of propionate to a member of the citric acid cycle and is therefore of significance in the process of gluconeogenesis. (Murray, 1996). The body is allowed to function normally with the help of the nutrients, which also help in building the body. Each nutrient has at least one specific function, and no other nutrient can cover for any of the others. Because different nutrients are needed to remain healthy, a wide variety has to be taken. REFERENCE Murray, RK., Daryl, KG., Peter, AM and Victor, WR .(1996). Harper’s Biochemistry. 24th edn, Stanford: Appleton & Lange, 600-620. Read, Donald, A and Walter, HG. (1973). Health and Modern Man. New York: The Macmillan Company, 285-288. Read More