10 Water
Water is unique. Although not considered a micronutrient, it is a nutrient nonetheless as it has many functions in the body. Water is considered to be an essential nutrient not because it has high nutritional value but because it performs many essential jobs. Although some water gets into the body through foods, it should be consumed in large amounts for adequate hydration (Grosvenor, Smolin, & Bedoya, 2014).
Water is present in all body tissue, it transports nutrients to cells and waste away from cells, and provides a method for the excretion of wastes from the body. Water aids in digestion, regulates body temperature, and is the liquid medium for all body fluids such as blood, perspiration, and urine. The body acquires water from fluids ingested, moisture in foods, and as an end product of the metabolism in the body of the macronutrients. In temperate climates, such as those found in much of Canada, the body needs the equivalent of about 2.5 L of water a day. Under severe physical conditions, the body’s need may increase by several litres a day depending upon the amount of fluid lost through sweating and evaporation through the lungs.
Consumption of water for good health should not be confused with the consumption of beverages. The majority of people have a beverage when they eat a meal at home or in another setting. Favourite beverages include soft drinks, bottled waters, juices, coffee, tea, and alcoholic beverages. Many of these contain ingredients that have an impact on the health of the body. Caffeine as a dietary side-product deserves special mention. About 60% of ingested caffeine in Canada is from coffee, with 30% from tea and 10% from cola and chocolate drinks. Although the research is not totally consistent, caffeine increases the frequency and prevalence of headaches, heart palpitations, and tremors while also increasing alertness during times of fatigue. Caffeine is addictive. After several hours of avoiding caffeine, heavy users can suffer withdrawal symptoms such as headaches, irritability, muscle tension, and nervousness—all of which disappear if caffeine is then consumed. Additionally, beverages that contain caffeine (and alcohol) act as diuretics and will actually draw water out of the body. The long-term effects of caffeine and the relationship between caffeine and chronic disease have not been fully established. However, the evidence linking coffee consumption (not necessarily caffeine consumption) with heart disease has prompted Health Canada to suggest that coffee should be consumed in moderation. (Health Canada, Caffeine in Foods, n.d.).
