The Importance and Function of Water in Health Maintenance - Essay Example

The Effects of Dehydration The importance and function of water in health maintenance Water is an essential requirement and component in living organisms. Water comprises approximately 60% of the human body weight. Approximately two-thirds of total body water can be found in the intracellular fluids while one-third is in the extracellular fluid. The extracellular water is made up of the interstitial fluid (eighty percent) and the blood plasma, where blood cells are suspended (Widmaier, Raff, & Strang, 2003). The functions of water can be related to its unique physical and chemical properties. Due to its polar nature, it is the universal solvent, being able to dissolve many compounds and serves as transport of compounds to other parts of the body. It also serves as a medium for many chemical reactions, acting as either reactant or product (Wardlaw & Hampl, 2007; Jéquier & Constant, 2009). Water also has the important function of thermoregulation due to its high heat capacity. Temperature is not drastically reduced or increased which is important in maintaining the integrity of cells. Waste excretion is another function that is attributed to water’s property to easily dissolve many substances. Many waste products are water-soluble and hence, are easily transported to the excretory system. Being incompressible, water can also serve as lubricant of joints, and in the production of amniotic fluid, saliva, and bile. Saliva aids in digestion, bile is involved in fat metabolism and breakdown, while amniotic fluid serves as a shock absorber that protects the developing fetus (Wardlaw & Hampl, 2007). In the body, water is important in the maintenance and continuation of the function of the circulatory system. Blood plasma, as it circulates in blood vessels, exchanges metabolic products, oxygen, nutrients and wastes with the interstitial fluid. Thus, dissolved substances in the plasma and interstitial fluid are similar, except that the plasma has more protein. However, the extracellular fluid differs largely from the fluid encompassed within the cells. The maintenance of these differences in fluid composition is one way for the cells to regulate their individual activities, like growth and metabolic activities. Cellular morphology is maintained by keeping a balance between electrolytes, osmotica, and water. Water requirement of the body The recommended water requirement for a healthy life has been published in many journal articles. Generally, these were based on intake levels that were expected to be nutritionally sufficient for health. It should be noted that water requirement is affected by climate, level of physical activity and renal solute load, which makes it difficult to come up with general values for water requirements. Some countries do not include it in dietary reference values while others recommend water requirements based on energy intake (Department of Health, 1991; National Research Council, 1989). The common recommendation is for a sedentary adult to drink 1.5 liters of water per day. This is deemed essential for body hydration (Jéquier & Constant, 2009). The requirement is increased for an individual with an active lifestyle or for those who are ill or dehydrated. The most common reminder has been to “drink eight glasses of water a day.” This admonition is also called “8 X 8”; to signify that each of these eight glasses must have 8 ounces (227 milliliters). The total volume recommended by the 8 X 8 rule is therefore roughly 2 quarts or 1.9 liters. The large volume of water recommended for intake has prompted some authors to modify this rule to include all sources of dietary fluids (including those coming from fruits, vegetables, juices), for those individuals with moderate levels of physical activity and living in temperate countries (Valtin, 2002). Nevertheless, higher daily intakes have been recommended at 3.7 liters (adult men) and 2.7 liters (adult women) (Wardlaw & Hampl, 2007). The fluid output goes through urine, feces, lungs, and skin (perspiration). Dehydration and its effects Dehydration is defined as a condition when the output of body water exceeds its input. In this definition, all sources of water should be considered to include those coming from food and beverages aside from the regular drinking water. Losses or output include perspiration, feces, urine, and even blood. In maintaining water balance, the output and input should be equal. The body tightly controls water intake and loss in order to precisely maintain balance. Warning signs of dehydration are dizziness, nausea, dry eyes, fatigue, and thirst. A loss of 1% in body mass attributed to water loss can normally be corrected within a 24-hour period. Maintenance of water balance poses no problem for healthy adults, but infants and the elderly population suffer easily from the effects of dehydration (Kleiner, 1999). A 4% body weight loss results in muscle strength while weakness sets in at 10%. Death can occur when excessive loss of water results in 20% loss in body mass. Dehydration can happen quickly during rigorous exercise and there is too much sweating, or during illnesses like diarrhoea. Increasing evidence also points to the role of mild dehydration in the development of disease (Manz, 2007). Mild hypohydration may be involved in prolonged labour during childbirth, cystic fibrosis, renal toxicity, and exercise asthma. Local and sudden dehydration can also cause loss of consciousness, speech incoherence, weakness of extremities and lowered blood pressure. Dehydration has also been found to cause arthritis, heartburn, migraine, angina, and increase in blood pressure (Vollmond, 2009). In contrast, good hydration was found to positively affect urinary tract infection, constipation, stroke, dental disease, diabetes, gallstone disease, and glaucoma (Manz, 2007). Effect of caffeine and alcohol on hydration of the body Early studies have shown that the intake of caffeine and alcoholic drinks cause diuresis or increased urine excretion. The intake of caffeine-containing beverages like tea has been discouraged to reduce dehydration. For this reasons, when assessing liquid intake, the contribution of alcoholic and caffeinated drinks are downsized or excluded altogether. However, for individuals who are used to consuming caffeinated drinks, recent research has shown that the intake of such beverages do not increase urine volume, and do not negatively affect hydration status (Grandjean, Reimers, Bannick, & Haven, 2000). On the contrary, these drinks contribute a significant volume to the total water intake (Institute of Medicine and Food and Nutrition Board, 2004). Alcohol is also traditionally considered a diuretic and a major contributor to water loss by its inhibitory effect on the capability of the kidneys to reabsorb water. Alcohol inhibits the action of antidiuretic hormone on forcing the kidney to retain water. Persons who consume too much alcohol usually wake up feeling dehydrated after losing liquid due to diuresis or frequent urination (Wardlaw & Hampl, 2007). However, contrasting reports to the effect of alcohol have also been published. It was shown that there is increased urine output three hours after taking an alcoholic drink, but anti-diuresis takes place after six hours. Such an effect, which could last for twelve hours after alcohol consumption, has been attributed to the suppression of vasopressin action on the kidneys (Taivainen, Laitinen, Tahtela, Kilanmaa, & Valimaki, 1995). Vasopressin is a peptide hormone that has an anti-diuretic action. The Institute of Medicine conducted a review of literature on the topic and came up with a similar conclusion that the effect of ethanol on increased urine excretion was transient and does not result in dehydration in a 24-hr period (Institute of Medicine and Food and Nutrition Board, 2004). Functions of the different electrolytes sodium, potassium, and chloride in the body Sodium, potassium and chloride ions are the body’s three main electrolytes. Electrolytes have the capacity to conduct electricity and are essential in normal cell functions. Electrolytes maintain water in extracellular compartments, buffer cell solutions, participate in membrane excitation and regulate blood clotting (Widmaier, Raff, & Strang, 2003; Stoppler, 2008). Sodium is the major cation in extracellular fluid. It regulates total volume of body water. The movement of sodium in and out of cells generates electrical signals necessary for communication of many processes in muscles, brain, and nervous system. Potassium is the major intracellular cation. It is involved in regulating heartbeat and muscle function. Chloride is an anion (negatively charged) and is found in extracellular and blood fluid. It is involved in maintaining a balance of body fluids. In concert with sodium, changes in chloride concentration can cause the sensation of thirst, which when alleviated, reduces the risk of dehydration and restores the balance of ions. Prevention of dehydration Dehydration can be prevented by consuming fluids and foods that are high in water (Mayo Clinic, 2009). The Institute of Medicine recommends that healthy individuals should let thirst be the signal for the need to rehydrate. However, there are cases when extra water should be given without waiting for thirst to be felt. Illness. Water should be given immediately at the first signs of illness, even when dehydration is not yet apparent. Drinks with too much sugar or too little sodium should be avoided since they do not have added electrolytes. Exercise. It s also recommended that hydration should be increased a day before strenuous physical activity, and should continue well after the activity has been completed to replenish the water lost due to perspiration. Hot weather conditions.Taking in enough fluids is also essential in hot and humid weather when sweating is common. Dry and hot weather conditions also increase risk of dehydration; this is more dangerous because skin loses moisture to the environment and may go unnoticed due to the absence of perspiration. Prevention of sweating can be improved by wearing clothing that decreases the absorption of heat or cools the skin like thin shirts, hats or parasols. References Department of Health. (1991). Dietary Reference Values for Food, Energy and Nutrients for the United Kingdom. London: The Stationery Office. Grandjean, A. C., Reimers, K. J., Bannick, K. E., & Haven, M. (2000). The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. Journal of the American College of Nutrition, 19, 591-600. Institute of Medicine and Food and Nutrition Board . (2004). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate . Washington, DC: Institute of Medicine and Food and Nutrition Board . Jéquier, E., & Constant, F. (2009). Water as an essential nutrient: the physiological basis of hydration. European Journal of Clinical Nutrition, advance online publication, doi: 10.1038/ejcn.2009.111. Kleiner, S. (1999). Water: an essential but overlooked nutrient. Journal of the American Dietetic Association, 99, 200-206. Manz, F. (2007). Hydration and disease. Journal of the American College of Nutrition, 26 (5), 535S-541S. Mayo Clinic. (2009, July 25). Dehydration. Retrieved October 15, 2009, from MayoClinic.com: http://www.mayoclinic.com/health/dehydration/DS00561/DSECTION=prevention National Research Council. (1989). Recommended Dietary Allowances (10th ed.). Washington: National Academy Press. Stoppler, M. (2008, November 14). Electrolytes. Retrieved October 16, 2009, from MedicineNet.com: http://www.medicinenet.com/electrolytes/page2.htm Taivainen, H., Laitinen, K., Tahtela, R., Kilanmaa, K., & Valimaki, M. (1995). Role of plasma vasopressin in changes of water balance accompanying acute alcohol intoxication. Alcoholism: Clinical and Experimental Research, 19, 759 –762. Valtin, H. (2002). “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 X 8”? American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, 283, 993-1004. Vollmond, N. (2009, June 5). Effects of Dehydration. Retrieved October 15, 2009, from Buzzle.com: http://www.buzzle.com/articles/effects-of-dehydration.html Wardlaw, G., & Hampl, J. (2007). Perspectives in Nutrition (7th ed.). New York: The McGraw-Hill Companies. Widmaier, E., Raff, H., & Strang, K. (2003). Human Physiology: The Mechanisms of Body Function (9th ed.). New York:The McGraw-Hill Companies. Read More