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Chapter 10 WATER AND THE ELECTROLYTES Water Water is an essential nutrient that must be consumed for survival. Water is a polar solvent in the body. The polarity of water comes from hydrogen and oxygen. Blood is 90% water. Blood transports oxygen and nutrients to cells and removes carbon dioxide and waste products. Copyright 2012, John Wiley & Sons Canada, Ltd. Water Water functions as a lubricant and cleanser. Tears wash away dirt, synovial fluid lubricates joints, saliva assists in chewing, tasting and swallowing and spinal fluid protects against shock. Water assists in regulating body temperature by holding onto heat and changing temperature slowly. Copyright 2012, John Wiley & Sons Canada, Ltd. Water molecule Copyright 2012, John Wiley & Sons Canada, Ltd. Hydrolysis and Condensation Reactions Copyright 2012, John Wiley & Sons Canada, Ltd. Water and pH Balance Copyright 2012, John Wiley & Sons Canada, Ltd. Water in the Body About two-thirds of body water is found inside cells. Water inside cells is called intracellular fluid. Extracellular fluid is found outside the cells. Interstitial fluid consists of lymph, blood plasma and extracellular fluid. Intracellular fluid has the highest concentration of protein, extracellular fluid has less, and interstitial fluid has the lowest concentration of protein. Extracellular fluid has the highest concentration of sodium and chloride and a lower concentration of potassium. Intracellular fluid has the lowest concentration of sodium and the highest concentration of potassium. The fluid pressure of blood against the blood vessels is blood pressure. Copyright 2012, John Wiley & Sons Canada, Ltd. Osmosis Copyright 2012, John Wiley & Sons Canada, Ltd. Copyright 2012, John Wiley & Sons Canada, Ltd. Copyright 2012, John Wiley & Sons Canada, Ltd. Need for Water in the Body Compared to Intake Copyright 2012, John Wiley & Sons Canada, Ltd. Resources for Water in the Diet Copyright 2012, John Wiley & Sons Canada, Ltd. Bottled Water Health Canada defines bottled water as water intended for human consumption that is packed in a sealed container. It can be derived from natural sources such as springs and aquifers or from municipal water supplies. One quarter to one third of Canadian households use bottled water as their main source of drinking water. 70% choose bottled water because of taste and 25% perceive bottled water as safer and healthier. Similar standards are set by federal, provincial and/or municipal agencies for both bottled and tap water. Copyright 2012, John Wiley & Sons Canada, Ltd. Thirst Mechanism Copyright 2012, John Wiley & Sons Canada, Ltd. Antidiuretic Hormone Assists in Fluid Intake Copyright 2012, John Wiley & Sons Canada, Ltd. Consequences of Dehydration Copyright 2012, John Wiley & Sons Canada, Ltd. Electrolytes: Sodium, Potassium and Chloride The correct combination and amounts of electrolytes are essential for life. Distribution of electrolytes affects the distribution of water throughout the body. Sodium, potassium and chloride are the principle electrolytes in body fluids. Copyright 2012, John Wiley & Sons Canada, Ltd. Summary of Water and the Electrolytes Copyright 2012, John Wiley & Sons Canada, Ltd. Sodium Intake of Canadians CCHS collected information on Canadians’ intake of sodium and potassium. Sodium intake was expressed as the percentage of the population consuming above the UL. 90.2% of males (>19 years) above the UL 65.7% of women (>19 years) above the UL A concern is that excessive sodium intake is associated with increased risk for hypertension. Copyright 2012, John Wiley & Sons Canada, Ltd. Sodium Intake of Canadians (continued) Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension Hypertension is a serious public health concern in Canada. 20% of adult Canadians have hypertension (140/90 mm or greater). 20% of adult Canadians have prehypertension (120/80–139/89 mm). It is estimated that 17% of Canadians do not know they have hypertension. Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet The lower the amount of sodium in the diet, the lower the blood pressure. The average intake of sodium in the Canadian diet is 3400 mg. A reduction in sodium by 1000 to 1500 mg will reduce blood pressure in those with and without hypertension. The Sodium Reduction Strategy for Canada recommends that Canadians reduce their sodium intake to less than 2300 mg/day. Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet (continued) Diet and lifestyle are both involved in regulating blood pressure. Maintaining a desirable body weight, staying active and limiting alcohol consumption will assist in keeping blood pressure within the normal range. Consuming a diet described in Canada’s Food Guide or the Dash Diet will also help in keeping blood pressure within the normal range. Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet (continued) Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet (continued) Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet (continued) Food labels list the sodium-containing ingredients in the ingredient list. The Nutrition Facts panel gives the total amount of sodium in milligrams and as a percentage of Daily Value to help buyers compare food products. Food labels can also include nutrient content claims relating to salt or sodium. Hypertension Canada recommends that Canadians consume foods containing 200 mg of sodium per serving but avoid foods that contain more than 400 mg of sodium per serving. Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet (continued) Copyright 2012, John Wiley & Sons Canada, Ltd. Hypertension and Diet (continued) Copyright 2012, John Wiley & Sons Canada, Ltd. Potassium Intake of Canadians The average Canadian diet contains 2500 to 3500 mg of potassium/day, which is well below the recommendation of 4700 mg/day. Fruits and vegetables are the best source of potassium. Canadians do not meet the number of servings of fruits and vegetables recommended by Canada’s Food Guide. This is the reason for their low potassium intake. Following Canada’s Food Guide and Dash Diet recommendations would result in a potassium intake of 8000 to 10,000 mg/day. Copyright 2012, John Wiley & Sons Canada, Ltd. Potassium Intake of Canadians (continued) Copyright 2012, John Wiley & Sons Canada, Ltd. Copyright Copyright © 2012 John Wiley & Sons Canada, Ltd. All rights reserved. Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful. Requests for further information should be . addressed to the Permissions Department, John Wiley & Sons Canada, Ltd. The purchaser may make back-up copies for his or her own use only and not for distribution or resale. The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein. Copyright 2012, John Wiley & Sons Canada, Ltd.