Nutrients Role in the Human Body - Essay Example

?Nutrients Introduction Consumption of food is a regular activity for human beings. There is a reason behind this. There are many raw materials essential to the human body, which need to be made available in a predetermined form. Food is the source of these predetermined raw materials, as the human body cannot make these raw materials, which are called nutrients. Nutrients are essential to the human body, as they are the source from which the human body gets its energy and other materials for its metabolic needs. Absence of any of these nutrients can lead to a state of malnutrition, wherein the normal physiological functions of the body are affected (1). The Six Classes of Essential Nutrients Proteins, carbohydrates, water, lipids, minerals, and vitamins are the key essential nutrients for the human body. Proteins carbohydrates, water, and lipids are classified as macronutrients, while minerals and vitamins are classified as micronutrients (1). Insel et al, 2011, p.230, define proteins as “large molecules made up of amino-acids joined in various sequences”. Thus various kinds of proteins are present in the human body in various shapes. Based on their shapes the several kinds of proteins have specific roles within the human body. Some of them are enzymes, and speed up the many chemical reactions within the body essential to its survival. Some others act as hormones. Hormones may be viewed as chemical messengers within the human body. Yet other hormones go into the makeup of the antibodies of the human body to protect the human body from foreign substances and pathogens. Some other proteins act as pumps within the body to maintain fluid balance. In this balance maintaining process they pump molecules across cell membranes and attract water. The acid base balance in the body is maintained by the action of proteins through the taking up or releasing of hydrogen ions, depending on the need. Finally, proteins act as transporters for many key substances like oxygen and the micronutrients to the targeted cells all over the human body. The essential nature of proteins to the human body is thus clear (2). Insel et al, 2011, p.146, define carbohydrates as “organic compounds that contain carbon (C), hydrogen (H), and oxygen (O) in the ratio of two hydrogen atoms and one oxygen atom for every carbon atom.” The main role of carbohydrates in the body is to act as a fuel for the cells in the human body. Even though the human body can use fats also for energy purposes, carbohydrates are the preferred source of energy, particularly for the brain, red blood cells, nervous system, fetus, and placenta. Carbohydrates also contain fibres that make it easier for the passage of stools through the digestive system (2). Water is absolutely essential for the survival of the human body. The water content in the human body is responsible for up to 75% of the weight of the human body. The importance of water to the human body lies in it being a very good solute. In the human body water carries several dissolved minerals in the form of electrolytes. These electrolytes are maintained at a constant balance. The very existence of cells in the human body depends on the maintenance of the right balance of these electrolytes in water (2). Insel et al, 2011, p.182, describe lipids as “a broad range of organic molecules that dissolve easily in organic solvents like alcohol, ether, and acetone, but are much less soluble in water.” Three main types make up the lipids, which are triglycerides, phospholipids, and sterols. Lipids are an energy source for the body and when stored in the body as fat act as energy reserves in the body for use when there is a deprivation of carbohydrate supplies to the body (2). Ball 2004, p. 8, defines vitamins as “a group of organic compounds which are essential in very small amounts for the normal functioning of the body.” Vitamins as required for nutrition in the human body are thirteen in number and classifies into water soluble vitamins and fat soluble vitamins. The water soluble vitamins are vitamin C and the eight components of the vitamin B group. The fat soluble vitamins are vitamin A, D, E, and K. These vitamins are in involved in various biochemical and physiological functions of the human body. Deficiency of any of these vitamins results in the development of vitamin deficiency diseases (3). Minerals are a class of nutrients that are inorganic elemental atoms or ions, unlike the other organic molecule nutrients. The essential minerals to the human body are divided into major minerals and trace minerals based on the quantum of their requirement in the human body. Calcium, magnesium, and phosphorus are examples of the major minerals, and iron, selenium and iodine are examples of trace minerals. These minerals have various essential roles in the human body. For instance among the major minerals, calcium and phosphorus are responsible for making the bones in the body hard, while magnesium plays the role of a catalyst in many of the chemical reactions that occur in the body. The importance of the trace elements to the functions in the human body lies in their serving as cofactors for enzymes, being components of hormones, and participants in the oxidation and reduction chemical reactions in the human body (2). Dietary Reference Intakes (DRI) After several years of study and consultations the Institute of Medicine (IOM) of the U.S. National Academy of Sciences brought out a set of recommendations pertaining to nutritional intake for humans. These recommendations are known as the Dietary Reference Intake (DRI). The DRI has four nutrient based values for reference that can be utilized for the evaluation and planning or a healthy population. These four reference values are Estimated Average Requirement (EAR), the Recommended Dietary Allowance (RDA), Adequate Intake (AI), and the Tolerable Upper Intake Level (UL). The DRI defines EAR as “the average daily nutrient intake level that is estimated to meet the requirements of half of the individuals in a particular life stage and gender group,” RDA as “the average daily nutrient intake that is sufficient to meet the nutrient requirements of nearly all (97-98 percent) healthy individuals in a particular life stage and gender group,” AI as “the recommended daily average intake level based on observation or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently health people that are assumed to be adequate; used when an RDA cannot be determined,” and UL as “the highest average daily nutrient intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population. As intake increases above the UL, potential risk of adverse effects may increase” (4). These values for nutrient have been made with the objective of assisting individuals to maintain optimal health and prevent disease through avoidance of excess consumption of nutrients. Though developed for the U.S.A and Canada, these nutrient values hold out the means of maintaining optimal health and prevention of disease development due to excess nutrient consumption across the world (4). Digestion and the Digestive System Digestion is the process within the human body whereby the food consumed is broken down into nutrient substances by the digestive system, which can then be absorbed for utilization in the body, and the waste products excreted. The major components of the digestive system are the mouth, the esophagus, stomach, small and large intestines, gall bladder, pancreas and liver. The point of ingestion of food is the mouth. Though very little digestion actually takes place in the mouth, it is the point at which the food is masticated into a form in which can travel through the digestive tract. In addition, the food is well mixed with saliva produced by the salivary glands in the mouth. In addition to lubricating the masticated food, saliva initiates the digestive process through the starch-digesting enzyme by converting starch into maltose. With the help of the tongue the food passes from the mouth into the esophagus, which acts as the conduit for transporting food into the stomach. In the stomach food is churned with gastric juices secreted by the stomach. Gastric juice contains hydrochloric acid and digestive enzymes. Churning of the food in the stomach converts it into chyme, which is converts the food into a semi-solid mass consisting of partially digested food through the digestive action of hydrochloric acid and gastric juices. Chyme passes from the stomach into duodenum of the small intestine. The pancreas secretes pancreatic juice into the duodenum. Bile secreted by the liver is also made available at duodenum. Bile breaks down fats for the pancreatic juice to emulsify these fats, so that they are converted into an absorbable form. From the duodenum the food passes into the jejunum of the small intestine. In the jejunum the digestion process is completed through the action of the digestive enzymes. The food then passes into the ileum, where absorption of nutrients takes place. The digestive waste in liquid form then passes into the large intestine that plays the role of absorbing the water from the digestive waste and storing the waste till the time of excretion (5). Works Cited 1. Shetty, S. Prakash. Nutrition Immunity and Infections. Cambridge, MA: CABI. 2010. 2. Insel Paul, Ross Don, McMahon Kimberly & Bernstein Melissa. Nutrition. Fourth Edition. Sudbury, MA: Jones and Bartlett Publishers. 2011. 3. Ball, G. F. M. Vitamins: Their Role in the Human Body. Oxford: Blackwell Publishing Limited. 2004. 4. Institute of Medicine of the National Academies. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: The National Academies Press. 2006. 5. Rogers, Kara. The Digestive System. New York: Britannia Educational Publishing. 2011. Read More