The Importance of Proper Nutrition - Coursework Example

Nutrition Running head: IMPORTANCE OF NUTRITION Importance of nutrition Write here Write the of the here Introduction Feeding represents one of the basic properties of living organisms. It provides the necessary energy for proper metabolic and organic functions. In order to have a healthy life, however, a person's energy intake must be balanced with energy expenditure. If this balance is disturbed, certain pathological conditions occur. When a person is overfed and the energy intake is exceedingly larger than the energy expenditure, the excess energy is stored in the adipose (fat) tissue, and leads to increased body mass and obesity. The opposite happens when the energy intake is insufficient to meet the body's metabolic needs- loss of body mass and starvation. Proper feeding, however, does not include only intake of food. The body depends on various types of substances such as proteins, carbohydrates, vitamins, fats and minerals, and an appropriate balances must be maintained among these substances so that all segments of the body's metabolic systems can be supplied with the necessary materials. Therefore, a variety of food must be used in order to have a proper diet. Energy and dietary characteristics of biochemical substances. The various substances that are introduced to the human organism have a specific energy value. According to Guyton, the energy liberated from each gram of carbohydrate as it is oxidized to carbon dioxide and water is 4.1 Calories (1 Calorie equals 1 kilocalorie), and that liberated from fat is 9.3 calories. The energy liberated from metabolism of the average protein of the diet as each gram is oxidized to carbon dioxide, water and urea is 4.35 calories. Also, these substances vary in the average percentages that are absorbed from the gastrointestinal tract: about 98 per cent of the carbohydrate, 95 per cent of the fat, and 92 percent of the protein. The average daily requirement for proteins is 30 to 50 Grams. 20 to 30 grams of the body proteins are degraded and used for producing other body chemicals daily. Therefore, all cells must continue to form new proteins to take the place of those that are being destroyed, and a supply of protein is needed in the diet for this purpose. An average person can maintain normal stores of protein, provided that the provided that the daily intake is above 30 to 50 grams. During normal conditions, carbohydrates represent the most important source of energy for the metabolic needs of the organism. Glucose represents the main energy source of the brain. The British Nutrition Foundation states that carbohydrates should supply a minimum of 47 percent of our total daily calories. For example in a standard 2000 calories diet, the daily intake should be around 250 grams. One of the main purposes of fats is that they represent energy reserves. Indeed they do have the largest energetic value, but the body utilizes them after using up the reserves of carbohydrates. After the fats and carbohydrates are depleted, the body rapidly consumes the stores of protein. This makes the fats as, well as the carbohydrates, substances called protein sparers. It is estimated that the daily intake should be around 65 g. It must also be mentioned that all three types of substances play a part, either small, like the carbohydrates, or large like proteins and fats, in the body's structure. Vitamins represent organic compounds that have a major role in the functioning of the various enzymes throughout the body. They are needed in small quantities, like vitamin B12, whose daily intake is 3 micrograms. Vitamin C or ascorbic acid is the only vitamin that differs, whose daily intake is 45 mg. There are also a variety of minerals and inorganic compounds that play a multitude of vital roles throughout the organism. Amongst the most prominent are calcium, potassium, sodium and iron. Calcium, potassium and sodium have high values of intake (calcium- 1000 mg, sodium- 2400 and potassium-3500 mg) while the daily intake of iron is 18 mg. - Nutrition during various stages of life As the human organism changes during its course through life, so does the nature of the diet. During different times of life, different amount of nutritious compounds is necessary. Therefore, the nature of the diet is divided according to the human lifecycle; there is nutrition during infancy, childhood, adolescence, adulthood and old age. Pregnancy also represents a unique phase of human life, and has its own particular diet. Infancy The goal of infant nutrition is to promote optimal growth and development. Unlike adults, they do not require variety to secure nutrition during the first six months or so of life. Except for fluoride and vitamin D (in the absence of sunlight), human milk alone provides the vitamins, minerals, carbohydrates, fats, and proteins needed for normal growth and development during early infancy. Breast milk provides the infant with 30-40% of the energy from carbohydrates and 50% from fat, while the rest belongs to the proteins. This energy is used for several reasons, such as: to maintain the basic metabolic functions, to induce growth, for specific dynamic effects of food, energy lost from excretion and the necessary energy for body's activities. During the first year, the daily requirement of proteins, which is most important for growth and development is 1.5 g/per kilogram of child weight, and sometimes, during the first months of life, even 2.3 g/kg a day. During further development the amount of necessary proteins is reduced. - Childhood At this age, recommendations for diet content are similar to those for older individuals. Challenges here relate to providing quality nutrient intake and avoiding excess caloric intake. Dairy products are a major source of saturated fat and cholesterol in this age group, and therefore a transition to low-fat milk and other dairy products is important. Sweetened beverages and other sugar-containing snacks are a major source of caloric intake. Parents should remember that they are responsible for choosing foods that are eaten and when and where they are eaten. The child is responsible for whether or not he or she wants to eat and how much. Two natural parental impulses, pressuring children to eat and restricting access to specific foods, are not recommended because they often lead to overeating, dislikes, and paradoxical interest in forbidden items. Adolescence As children grow up, sources of food and influences on eating behaviour increase. Social constraints on families may necessitate the presence of multiple caregivers, eating out, and frequent fast food consumption. Adolescence is a nutritionally vulnerable developmental stage because growth rate accelerates. Amplified caloric and global nutrition needs due to pubertal growth stimulate appetite. The combination of centrally driven appetite stimulation and an increasingly sedentary lifestyle due to a decline in recreational sports participation augments obesity. Parallel to the psychosocial transition from dependence on parental authority to independent thought processes, food choices and purchases are increasingly made by the adolescent. This change in lifestyle and in activities lead to greater consumption of excess fat, saturated fat, trans fats, and added sugars along with insufficient consumption of micronutrients such as calcium, iron, zinc, and potassium, as well as vitamins A, D, and C and folic acid. Usually, the amount of proteins that should be included in the diet is 0.9 g/kg, while the amount of fat and carbohydrates slowly conforms to the adult levels of necessary intake. - Pregnancy Pregnancy represents a very unique phase of the female organism, and so it has a unique influence on the metabolism and diet. In essence, the future mother is eating in order to supply hers and her child's organism with the proper nutrients. The proper diet during pregnancy does not differ much from the standard diet and balance of proteins, fats, carbohydrates, vitamins and minerals. There are certain modifications to the diet that are necessary to be maid. It is recommended that pregnant women consume an additional 300 calories over their normal intake requirements. Dieting and the urge to eat in large quantities during pregnancy should be avoided. Complex carbohydrates should also be consumed (those found in pastas and beans) instead of simple carbohydrates (found in white bread and cookies). Proteins are also important during pregnancy and should be consumed around 70-75 grams daily. High-fat foods should be limited to four servings daily (no more than 30% of total calories from fat). However, eliminating all fat is dangerous; essential fatty acids are important, including omega-3-fatty acids. - Old age As adults age, calorie needs decrease, but nutrient needs stays the same. A decreased intake of food and changes that occur with aging can make it hard to fulfill daily recommendations. Likewise, people in specific populations may find it difficult to consume adequate amounts of vitamins and minerals. It is recommended thatpeople over the age of 50 should consume the crystalline form of vitamin B-12 supplement or eat foods fortified with vitamin B-12, such as breakfast cereals. Extra vitamin D from fortified foods and supplements should also be consumed. Older adults who participate in regular physical activity may experience fewer functional declines typically associated with aging. Fiber-rich foods should be consumed to avoid constipation. No more than 1,500 mg sodium should be consumed per day. Foods containing potassium should be taken to meet the recommendation of 4,700 mg per day. Dark green and orange vegetables, cantaloupe, bananas, oranges, beans and tomato products are examples of foods that provide potassium. - Abnormal conditions in dieting Any misbalance in the intake of nutrients may lead to abnormal conditions, 2 of which are most famous: obesity and malnutrition. Obesity As we stated at the beginning, when greater quantities of energy (in the form of food) enter the body then they are expended, the body weigh increases. Therefore, obesity is caused by energy intake in excess of energy output. For each 9.3 calories of excess energy that enter the body, 1 gram of fat is stored. Excess energy input occurs only during developing phase of obesity. Once a person has become obese, all that is required to remain obese is the energy intake equal the energy output. For the person to reduce in weight, the intake must be less than the output. When the stores of energy exceed the optimal level for a normal person, feeding is automatically reduced to prevent an excess of stored energy. However, in many obese people this is not true, because feeding in these persons does not slacken until body weight is far from normal. Therefore, in effect, obesity is often caused by an abnormality of the feeding regulatory mechanism. This can result from either psychogenic factors that affect this regulation or actual abnormalities of the regulatory system itself. Malnutrition Malnutrition represents a deficiency in one or more nutritious substances that the human organism has to bring from the outside. Therefore, the level of malnutrition is equal to the variety of foods that we introduce into the organism, except for several cases where disease is in question. The individual need of the human organism defer from person to person, and it is influenced from certain factors like age, sex, physical activity and even geographical regions. Nevertheless, consuming substances that the human organism cannot synthesize himself is most important. There are 2 types of malnutrition: primary malnutrition, also known as starvation and secondary malnutrition, caused by physiological diseases. The former will be explained in more detail, since it is closely connected to a person's diet. Even though the tissues preferentially use carbohydrate for energy over both fat and protein, the quantity of carbohydrate normally stored in the entire body is only a few hundred grams (mainly glycogen in the liver and muscles), and it can supply the energy required for body function for perhaps half a day. Therefore, except for the first few hours of starvation, the major effects are progressive depletion of tissue fat and protein. Because fat is the prime source of energy (100 times as much fat-energy is stored in the normal person as carbohydrate-energy), the rate of fat depletion continues unabated, as shown in Figure 71-2, until most of the fat stores in the body are gone. The proteins undergo three phases of depletion: rapid depletion at first, then greatly slowed depletion, and, finally, rapid depletion again shortly before death. The initial rapid depletion is caused by use of easily mobilizable protein for direct metabolism or for conversion to glucose and then metabolism of the glucose mainly by the brain. After the readily mobilizable protein stores have been depleted during the early phase of starvation, the remaining protein is not so easily removed. Ai this time, the rate of gluconeogenesis decreases to one third to one fifth its previous rate, and the rate of depletion of protein becomes greatly decreased. The lessened availability of glucose then initiates a series of events that leads to excessive fat utilization and conversion of some of the fat breakdown products to ketone bodies, producing the state of ketosis. The ketone bodies, like glucose, can cross the blood-brain barrier and can be used by the brain cells for energy. Therefore, about two thirds of the brain's energy now is derived from these ketone bodies, principally from beta-hydroxybutyrate. This sequence of events thus leads to at least partial preservation of the protein stores of the body. There finally comes a time when the fat stores also are almost depleted, and the only remaining source of energy is proteins. At that time, the protein stores once again enter a stage of rapid depletion. Because proteins are also essential for maintenance of cellular function, death ordinarily ensues when the proteins of the body have been depleted to about one half their normal level. When vitamins are concerned, the stores of some of the vitamins, especially the water-soluble vitamins-the vitamin B group and vitamin C-do not last long during starvation. Consequently, after a week or more of starvation, mild vitamin deficiencies usually begin to appear, and after several weeks, severe vitamin deficiencies can occur. These deficiencies can add to the debility that leads to death. - Sports and dieting The factor that most dramatically increases metabolic rate is strenuous exercise. Short bursts of maximal muscle contraction in a single muscle can liberate as much as 100 times its normal resting amount of heat for a few seconds. For the entire body, maximal muscle exercise can increase the overall heat production of the body for a few seconds to about 50 times normal, or to about 20 times normal for more sustained exercise in a well-trained individual. It is determined that one of the most energy-consuming activities are swimming, which spends 500 cal/hour, running, around 570 cal/h and walking up stairs rapidly, which requires 1100 cal/h. Sleeping and lying awake and still are at least energy-consuming, with 65 and 70 cal/h, respectively. Because of the great variation in the amount of physical activity among individuals, this component of energy expenditure is the most important reason for the differences in caloric intake required to maintain energy balance. However, in affluent countries, where food supplies are plentiful, caloric intake periodically exceeds energy expenditure, and the excess of energy is stored mainly as fat. This underscores the importance of maintaining a proper level of physical activity to prevent excess fat stores and obesity. Even in people who perform little or no daily exercise or physical work, significant energy is spent on spontaneous physical activity required to maintain muscle tone and body posture and no other non-exercise activities. These non-exercise activities account for about 7 per cent of a person's daily energy usage. References: 1. Stjepan Gamulin, Matko Marusic, Zdenko Kovac and associates; Pathophysiology, 5th edition; Medicinska naklada, Zagreb, 2002 2. Sloboda A. Dzekova- Stojkova; Biochemistry; NIP Forum, Skopje, 1999 Read More