The human body is 75% water. With normal daily body functions, it loses a considerable amount of it. Frequently, people miss this fact and do not realize the importance of proper hydration for organs to work correctly.
“Water is essential for life. From the time that primeval species ventured from the oceans to live on land, a major key to survival has been the prevention of dehydration. The critical adaptations cross an array of species, including man. Without water, humans can survive only for days. Water comprises from 75% body weight in infants to 55% in the elderly and is essential for cellular homeostasis and life. Nevertheless, there are many unanswered questions about this most essential component of our body and our diet.”1
One of these questions is, what is the right amount of water to drink? The truth is that each body has different needs, including water. However, as the basis for all body fluids (blood, sweat, urine, and digestive juices), losing excessive amounts of water provokes dehydration. In extreme cases, it can cause death. “Dehydration occurs when you use or lose more fluid than you take in, and your body doesn’t have enough water and other fluids to carry out its normal functions. If you don’t replace lost fluids, you will get dehydrated. Anyone may become dehydrated, but the condition is especially dangerous for young children and older adults. The most common cause of dehydration in young children is severe diarrhea and vomiting. Older adults naturally have a lower volume of water in their bodies, and may have conditions or take medications that increase the risk of dehydration.”2
When Do We Lose Water?
“For sedentary to moderately active individuals under temperate conditions, water is lost from the body via urine, feces, respiration, and evaporation. During increased physical activity and in conditions other than temperate, sweat loss contributes to body water loss. The minimal amount of fluid loss that can occur is referred to as the obligatory water loss. However, a variety of factors can affect obligatory loss. For example, obligatory urine loss occurs because of the need to remove various solutes from the body. The minimum water required for urine is dependent on the daily solute excretory load, primarily determined by diet, and the maximum urinary concentration achievable. Urinary concentrating ability varies with age and with renal disease. Under normal conditions, fecal water loss is quite small, estimated at about 100 mL/day.”3
We lose water while performing daily body functions, such as:
- Bowel movements.
Consequently, body water levels are always changing. When people lose more water than they drink, dehydration occurs. For this reason, water consumption will depend on the levels of activity. Ideally, 1.5 or 2 liters per day are enough to recover the amount of water that has left our body.
Frequent Causes of Dehydration
“Dehydration may be brought about in two main ways: (A) Insufficient intake of water. (B) Loss of bodily secretions from the alimentary tract or loss of sweat. Insufficient intake of water occurs when water is not available or when it cannot be drunk due to great weakness, unconsciousness or dysphagia from some local cause. Loss of bodily secretions in this country usually results from vomiting, diarrhea, fistula or gastric aspiration. Profuse sweating occurs in 346 tropical climates or under certain industrial conditions; occasionally it arises from mistaken over-heating of patients, especially unconscious patients by blankets or hot air cradles.”4
How to Prevent Dehydration
“To prevent dehydration, drink plenty of fluids, enough so that your urine is light yellow or almost clear like water. Choose water and other caffeine-free clear liquids until you feel better. Stay away from drinks with alcohol or caffeine. If you do not feel like eating or drinking, try taking small sips of water, sports drinks, or Gatorade.”5
Humans and other animals can detect when they require water to prevent dehydration. “The brain’s decision to start or stop drinking and to choose the appropriate drink is made before the ingested fluid can reach the intra- and extracellular compartments. The taste buds in the mouth send messages to the brain about nature, and especially the salt content, of the ingested fluid, and neuronal responses are triggered as if the incoming water had already reached the bloodstream. These are the so-called anticipatory reflexes: they cannot be entirely ‘cephalic reflexes’ because they arise from the gut as well as the mouth.”6
Proper Hydration and Chronic Diseases
Water consumption is efficient to prevent certain chronic diseases. “Water is quantitatively the most important nutrient. There is strong evidence showing that good hydration reduces the risk of urolithiasis. Less strong evidence links good hydration with reduced incidence of constipation, exercise asthma, hypertonic dehydration in the infant, and hyperglycemia in diabetic ketoacidosis. Good hydration is associated with a reduction in urinary tract infections, hypertension, fatal coronary heart disease, venous thromboembolism, and cerebral infarct but all these effects need to be confirmed by clinical trials. For other conditions such as bladder or colon cancer, evidence of a preventive effect of maintaining good hydration is not consistent.”7
Tips to Stay Hydrated
Hydration is essential for all body functions. “To keep your body hydrated, aim for a fluid intake of about: 3 L (12 cups) for men 19 years old and over each day. 2.2 L (9 cups) for women 19 years old and over each day.”8
Here are some useful tips to stay hydrated:
- Carry water with you. Bring water to outdoor activities, sports practices, or even during walks to replace the water you will lose.
- Avoid outdoors exercise or long walks outside in hot weather. High temperatures increase the loss of body fluids.
- Check the weather online or listen to weather forecasts before you make any outdoors plan.
- Do not force your body. If you’ll be exposed to hot weather, carry enough water and sit down for a few minutes to cool down, hydrate and keep on without forcing your body.
- Provide children and elders with enough liquids or water. Children and older adults require plenty of fluids to stay healthy and hydrated. Encourage them to drink enough water every day to assure proper body functions, not only when exposed to hot temperatures.
“The amount of water you need to drink each day will change. You will need to drink more if it is a hot day, or if you are exercising. Your body will tell you when you are thirsty. Dehydration means your body does not have enough water and being thirsty is often a sign of already being dehydrated.”9
Hydrating involves more than drinking water. “Fluids include water and other beverages such as milk, juice, broth or soups, coffee, and tea. Water is one of the best fluid choices, but it is a myth that you need 8 cups a day to stay healthy. Fluid helps you stay healthy and energized. It also: controls your body temperature aids digestion carries nutrients around your body cushions organs and joints gets rid of waste keeps your bowels regular Your body loses water by sweating, breathing and getting rid of waste. If you lose more fluid than you take in you can get dehydrated.”10
Ten Tips for Drinking More Water
- “On a sedentary day, try to drink around two liters of water.
- Start by drinking a glass of fresh water when you get up in the morning.
- If you are not used to drinking water regularly, try initially replacing just one of your other drinks a day with fresh water, increasing your consumption as the weeks go by.
- Ask for a glass of tap water to go with your coffee and tea in cafés.
- Drink a glass of water before and during each meal.
- Hot water with fresh mint, lemon balm or a piece of fruit in – like lime, lemon, orange etc – often helps those who want a hot drink.
- Carry a bottle filled with chilled tap water with you whenever you leave the house.
- During exercise, drink at 10 to 15-minute intervals or think of it as a full glass every 30 minutes – drink slowly and drink early, it’s physically easier to do this when you are still feeling fresh.
- Keep a check on your urine. As a general guide to hydration, it should be plentiful, pale in color and odorless.
- Ask for a jug of iced tap water with your meal when in restaurants and with your alcohol when in bars – good establishments will be happy to provide this.”11
Staying hydrated is a matter of common sense. However, light dehydration is still common in people who are sick or busy. Pay attention to the first signs of dehydration: thirst sensation, dry mouth and lips, dark urine, difficulty concentrating and irritability. Fortunately, preventing dehydration is simple: monitor urine color, drink water before being thirsty and have access to safe drinking water at all times. Call an emergency service if you see a case of severe dehydration.
(1, 6, 7) Water, Hydration and Health. Popkin, B., D’ Anci, K., & Rosemberg, I. Nutrition Reviews. 2010. https://academic.oup.com/nutritionreviews/article-abstract/68/8/439/1841926?redirectedFrom=fulltext
(2) Dehydration. Mayo Clinic Staff. Mayo Clinic. 2018. https://www.mayoclinic.org/diseases-conditions/dehydration/symptoms-causes/syc-20354086
(3) Water Requirements, Impinging Factors, and Recommended Intakes. Grandjean, A. World Health Organization. 2014. https://www.who.int/water_sanitation_health/dwq/nutwaterrequir.pdf
(4) The Maintenance Of Fluid Balance. Marriot, H. The Royal College Of Surgeons. 1950. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2238412/pdf/annrcse00041-0005.pdf
(5) Preventing Dehydration for People with Urinary Diversion. Spilak, D. University Of Michigan, Health System. 2015. http://www.med.umich.edu/1libr/urology/DehydrationPreventionUrinaryDiversion.pdf
(8, 10) Guidelines for Drinking Fluids to Stay Hydrated. Dietitians from Canada. 2014. https://www.dietitians.ca/getattachment/becace49-3bad-4754-ac94-f31c3f04fed0/FACTSHEET-Guidelines-for-staying-hydrated.pdf.aspx
(9) Drink Water Instead. Kidney Health Australia. 2017. https://kidney.org.au/cms_uploads/docs/drink-water-instead–kidney-health-australia-fact-sheet.pdf
(11) Hydration Best Practice Toolkit for Hospitals and Healthcare. Water UK. Water For Health. 2007. http://www.bournemouthwater.co.uk/Uploads/Docs/Hydration_Toolkit_-_Entire_and_In_Order.pdf