Fluids: Why Consumption is so Important
Fluids: Why Consumption is so Important
You've probably heard that you should be drinking 8 oz of water a day, but do you know why? If you are not a water drinker, should you be concerned? What about drinking coffee or tea? Read on to learn the truth about hydration.
Water Facts
-50% to 70% of our bodies consist of water; water makes up most of our blood, muscles, brain, and bone.
-Studies show that dehydration or water deficits of as little as 2% body weight can impair physiological performance and response.
-Dehydration of 5% to 7% body weight can cause dyspnea (difficulty breathing), headaches, dizziness, and apathy.
-Research also indicates that fluid consumption can affect the risk of urinary stone disease; cancers of the breast, colon, and urinary tract; childhood and adolescent obesity; mitral valve prolapse (irregular heartbeat); salivary gland function; and overall health in the elderly.
Fluids: How Much do You Need and What Can You Drink?
All of us have heard that we need to drink 8 glasses of 8 oz cups of water a day. While most of us might try to achieve these amounts - it is easy fall short. Some of us have a hard time drinking a total of 8 glasses of fluids a day. Therefore, if you are someone who drinks a few caffeinated beverages and/or carbonated beverages a day as well, that could mean you are drinking 10-12 or more cups of fluids a day!
I Heart Caffeine!
This brings us to the all-curious and important question: do caffeinated and carbonated beverages count as part of the required fluids a day? YES! Studies show that large doses of caffeine, about 250-300 mg, equivalent to the amount found in 2-3 cups of coffee or 5-8 cups of tea contributes to short-term stimulation of urine output in individuals who have not been ingesting caffeine containing beverages for a period of days or weeks. However, a tolerance to the diuretic and other effects of caffeine develops in individuals who regularly consume coffee or tea. Normal amounts of tea, coffee, and carbonated drinks found in standard servings appear to have no diuretic effects. Therefore, consumption of caffeinated and carbonated beverages as part of a normal lifestyle does not lead to fluid loss in excess of the amount ingested or is associated with poor hydration status.
Don't Like Water?
Studies show that water is not the only type of fluid that can account for total daily fluid intake. All types of fluids count in hydration, such as, juice, milk, coffee, tea and soft drinks (as previously mentioned). But remember that juice and soda can be packed with extra sugar and calories! We recommend diet soda or flavored carbonated water. Plus you can actually get water from eating foods such as fruit, soups, meats, and vegetables (just to name a few). At the end of the day, it is best to have about half of your daily fluid intake from water and the rest can be from other drinks or food.
What it All Means...
It is very important to get plenty of fluids throughout the day for vital bodily functions and physiological performance. However, we do not need 8 glasses of water; all drinks can contribute to the daily requirement of fluid. If you are a regular coffee, tea or soft drink drinker these beverages count as well. Also, water in food could account for one third or up to one half the fluids we need throughout the day. Therefore, a recommendation of approximately 6 cups of fluids is sufficient and only half needs be from pure water.
Created by Nancy Wong, BS, Dietetic Intern
Resources
Kleiner, Susan M., PhD, RD (1999) Water: An Essential But Overlooked Nutrient. J Am Diet Assoc. 99:200-206.
R. J. Maughan, J. Griffin (2003) Caffeine ingestion and fluid balance: a review
Journal of Human Nutrition and Dietetics 16 (6), 411-420.
Valtin, Heinz (2002) "Drink at least 8 glasses of water a day." Really? Is there scientific evidence for "8 X 8"? Am J Physiol Regul Integr Comp Physiol 283: R993-R1004