Fundamentals of Human Nutrition/Hydration

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14.4 Hydration

Water is one of the six essential nutrients that humans need to survive. Water is so important because it supports every cell in the human body, allowing the body to maintain proper hydration throughout the day (Hydration, 2015). Understanding the importance of hydration, consuming adequate amounts of liquid, and being aware of when at risk for dehydration are all important factors for humans to sustain proper hydration. 

Staying hydrated is critical. Water in the human body is used in every cell to support mental, physical, and everyday performance (Water balance, 2006). If the body is not hydrated it will slowly not be able to function. This will lead to dehydration, the opposite of hydration. Our bodies become dehydrated from everyday activities. Water is used every time the human body excretes waste, sweats, exhales, inhales, or has an increase in temperature (Hydration, 2015). Humans lose water rapidly throughout the day. Luckily hydration can be easily maintained if monitored regularly. 

The average daily recommendation for water consumption is six to eight eight-ounce cups of water every day (Hydration, 2015). A sign that an individual is not hydrated is when their urine appears yellow or if they are thirsty. Not every individual is the same when it comes to how much water they need to maintain hydration throughout the day. Those that are pregnant, have diabetes, have a heart disease, or other medical conditions are all at risk of becoming dehydrated quicker (Staying Hydrated, 2014). There are other various factors including temperature, clothing, and activity that can affect an individual’s state of hydration (Staying Hydrated, 2014). It is important to keep these factors in mind when trying to achieve daily hydration along with what enhances hydration. Water is not the only way to stay hydrated. Most drinks such as juice, soda, coffee, water, etc. can add to the body’s daily hydration (Water balance, 2006). Fruits and vegetables are also foods high in water that help the body stay hydrated (Staying Hydrated, 2014). 

When exercising or sweating individuals need to be aware of water loss and remember to keep sodium loss in mind. It is important to remember that following these events an individual should intake water along with a snack or a drink containing sodium such as Gatorade (Water balance, 2006). Sodium is important because it allows the body to absorb the water quicker which will help the individual to regain hydration (Water balance, 2006).  


Hydration: Why It’s So Important. (2015, March). Retrieved September 11,2015, from

Staying Hydrated – Staying Healthy. (2014, September). Retrieved September 11, 2015, from

Water balance, fluids and the importance of good hydration. (2006, June). Retrieved September 11, 2015, from

14.4.1 Types of fluid replacement

Where beverages are a significant source for water, foods can also have a high water content and can help to reach the daily recommended water intake. Specifically, many fruits and vegetables serve as good sources because they can contain upwards of 90 percent water content (“Hydrating”, 2014). Among these includes celery, watermelon, cauliflower, and tomatoes, as well as different kinds of peppers and berries. In particular, the food with the highest water content is cucumbers, which consist of 97 percent water. In extreme cases, such as dehydration or illnesses, beverages and foods may not be enough to supply the body with the water it needs. If this occurs, artificial hydration may be required (“Artificial Hydration”, 2000). This can be achieved through either one of two procedures, Intravenous (IV) fluid replacement, or subcutaneous fluid replacement called hypodermoclysis. IV fluid replacement involves putting the fluid directly into the vein, whereas hypodermoclysis involves putting the fluid underneath the skin. Artificial hydration can serve many benefits to someone who urgently needs to be rehydrated. However, it can also help to prevent a person from becoming dehydrated if they are unable to swallow foods or beverages (“Artificial Hydration”, 2000). Since it is important to closely monitor the patient receiving IV fluids, they are often administered in hospitals. This is so doctors and nurses can both watch and determine further courses of action to take to help the patient. With varying intensities and duration of exercises comes varying needs of fluid replacement (Maughan and Shirreffs, 2010). In particular, athletes can lose significant amounts of water through practice and intense exercise, so it is important for them to stay hydrated throughout their performance. Athletes should begin exercise well hydrated, and despite the type of exercise (aerobic or anaerobic), it is still important to maintain proper fluid intake at all times.

Even in cases where endurance exercises are being performed, dehydration and fluid loss will occur as long as sweat loss is higher than fluid intake (Maughan and Shirreffs, 2010). In some cases, if an athlete fails to adequately replace their electrolyte intake, but consistently replaces their water intake, hyponatremia may occur. This is where in longer periods of exercise- over 3 hours- the body begins to lose electrolytes, and with the increasing amounts of plain water, ultimately diluting the body’s fluids and resulting in dangerously low sodium concentrations. While all of these chiefly pertain to athletes, dehydration, rehydration, and hyponatremia should be a concern to anyone who exercises, especially over long periods of time without adequate fluid replacement. References: Family Doctor. (2009, September 1). Artificial hydration and nutrition. Retrieved November 30, 2015, from issues/artificial-hydration-and-nutrition.html Maughan, R., & Shirreffs, S. (2010). Dehydration and rehydration in competative sport. Scandinavian Journal of Medicine & Science in Sports, 40-47. Retrieved December 4, 2015, from The Physicians Committee. (2014, June 24). Hydrating through fruits and veggies. Retrieved November 30, 2015, from

14.4.2 Recommendations

Hydration Recommendations Staying properly hydrated is one of the most important factors for maintaining one’s health. Bodies need to have the correct amount of fluid in order to provide energy for daily tasks, drive organ systems, eliminate toxins, and complete a myriad of other tasks (Mayo Clinic Staff, 2014). While hydration is important to everyone’s health, the amount of fluids required to ensure proper hydration can vary greatly from person to person. Multiple studies on what constitutes adequate hydration have drawn multiple conclusions that all slightly differ. Several factors can affect one’s hydration needs, such as one’s level of activity, health, and even one’s environment (Mayo Clinic Staff, 2014). Despite these influences, there are some general guidelines that, if followed, will help a person maintain proper hydration. According to the Institute of Medicine and the Mayo Clinic Staff, in order to balance fluid loss on a daily basis, healthy males need to intake around 13 cups of fluid, and healthy females need around 9 cups (2014). These recommendations are similar to the popular 8X8 rule which states that an individual needs to consume around eight, eight ounce glasses of fluid a day (Mayo Clinic Staff, 2014). Environmental factors that could increase how many fluids an individual needs in a day are things like altitude and humidity levels. Health conditions that cause symptoms like diarrhea, vomiting, or high fever will require an individual to drink more fluids in order to replace those that have been lost. Two special populations that have different hydration recommendations are females who are pregnant or breast-feeding. These two populations, especially the nursing population, require a greater amount of additional fluids than what is advised for the general female population. Women who are breast-feeding are recommended to drink around thirteen

cups of fluid on a daily basis and women who are pregnant are advised to drink around ten cups of fluid on a daily basis (Mayo Clinic Staff, 2014). Due to the fact that each individual has different hydration needs, the Mayo Clinic Staff recommends consulting a doctor to learn what fluid intake is correct for each individual to avoid dehydration or over hydration (2014). Another group of people who has a different set of hydration guidelines is athletes or those involved in regular moderate to intense activity. This group of people needs to take several steps in order to maintain healthy levels of hydration before, during, and after exercising. The American College of Sports Medicine (ACSM) recommends establishing a baseline hydration level that will let an athlete/exerciser know the level they should try to stay around (Simpson and Howard, 2011). The ACSM also recommends that starting around four hours before an athlete/exerciser begins exercising, he or she drinks about sixteen to twenty ounces of fluid, preferably water or a sports beverage, and an additional eight to twelve ounces ten to fifteen minutes before becoming active (Simpson and Howard, 2011). If a person is going to be exercising for less than an hour, the ACSM recommends drinking three to eight ounces of water every fifteen to twenty minutes, and three to eight ounces of a sports drink every fifteen to twenty minutes if the exercise will last longer than an hour (Simpson and Howard, 2011). Another recommendation is to not drink more than a quart of liquid in less than an hour while exercising (Simpson and Howard, 2011). The last step is to replace the fluids that were lost. This can be done by drinking twenty to twenty-four ounces of fluid for every pound that was lost during the exercise (Simpson and Howard, 2011). The types of fluids that one chooses to hydrate with is also very important. In general, water is enough to maintain healthy levels, however if a person is exercising for longer than an hour or at a higher intensity, a sports drink may be more helpful. This is because sports drinks

contain electrolytes, calories, potassium, and various other nutrients that can help prolong the amount of time that an individual can perform an exercise. Even though these drinks can be helpful in maintaining proper hydration it is important to be aware that they can contain some less beneficial ingredients, such as caffeine and added sugars (Athletes, 2015). References Athletes: The Importance of Good Hydration. (2015, March 1). Retrieved December 1, 2015, from basics/athletes-the-importance-of-good-hydration.html Mayo Clinic Staff. (2014, September 5). Water: How much should you drink every day? Retrieved December 1, 2015, from healthy-eating/in-depth/water/art-20044256?pg=2 Simpson, M., & Howard, T. (2011). Selecting and Effectively Using Hydration for Fitness. Retrieved December 1, 2015, from effectively-using-hydration-for-fitness.pdf

14.4.3 Dehydration

Dehydration in the body arises when there is a loss of fluids in the body. The body can no longer carry out basic functions when it does not have enough water or fluids. During dehydration, the ratio of water leaving the body is higher than the ratio of water entering. Simple everyday functions like breathing and sweating also contribute to water loss in the bosy. Dehydration can be divided into three stages: mild, moderate, and severe. Mild and moderate cases can be balanced if an individual slowly drinks water or fluids that contain electrolytes. If left untreated severe cases can lead to death. Infants and the elderly are at higher risk for dehydration. People with chronic illnesses; such as diabetes, are at more risk of becoming dehydrated (Derrer, 2013). Furthermore, individuals with kidney and heart problems are also likely to become dehydrated. Suffering from dehydration can lead to serious complications such as seizures, swelling of the brain, and kidney failure. In severe conditions fluids may be given to a patient through an IV tube in order for the body to retain fluids more quickly (David, 2014). For specialists to confirm that a patient is suffering from dehydration doctors perform a series of tests. A blood sample test checks the concentration of electrolytes, such as, sodium and potassium in the body (David, 2014). Furthermore, a urinalysis test examines urine and evaluates the severity of the patients’ dehydration (David, 2014). Drinking plenty of fluids throughout the day and eating foods that are high in water content can avoid dehydration. For instance, fruits and vegetables like cucumbers and tomatoes can help maintain proper hydration. In hot and humid weather conditions individuals should drink additional fluids to replace the amount of water lost due to sweating. If someone is suffering from dehydration they should try to relocate to a cool and air-conditioned space. Alcohol consumption can increase an individual’s chances of being dehydrated, especially in warm weather (Dehydration, 2014). It is best to stay hydrated before and after starting physical work or vigorous exercise. Clear and diluted urine is a good sign that an individual is healthy and hydrated. Athletes should also monitor their fluid intake to prevent dehydration. Medical attention should be considered if someone experiences symptoms of diarrhea for more than 2 days or has a fever over 101° F (Derrer, 2013).

Common triggers of dehydration include:

  • Strong exercise
  • Hot weather
  • Fever
  • Vomiting or diarrhea

Symptoms between mild and moderate dehydration include:

  • Headache
  • Thirst
  • Dry and/or sticky mouth
  • Dark yellow urine
  • Fatigue

Symptoms of severe conditions include:

  • Dry, shrunken skin
  • Rapid heartbeat
  • Dizziness
  • Not urinating
  • High fever


David, C. (2014, July 7). Dehydration (Adults): Read About Treatment Options. Retrieved July 10, 2015, from

Dehydration. (2014, February 12). Retrieved July 10, 2015, from

Derrer, D. (2013, October 29). Dehydration Symptoms, Treatments, Causes, and Emergencies. Retrieved July 10, 2015, from

14.4.4 Heat Stroke

Heatstroke is a condition where the body has become overheated and can become dangerous or even fatal as the body reaches and passes 104° F. It is the condition caused by extreme hyperthermia, in which the body is unable to cool itself by evaporating sweat. Heatstroke is often caused by strenuous physical activity in hot weather, but can occur in the absence of heat or exercise (Lissoway). Exertional heatstroke is caused by physical activity in hot weather and is considered to be the first or second leading cause of death among young athletes up to high school (CDC). Classic heatstroke usually affects elderly people who are exposed to heat through multiple consecutive days and remain dehydrated.

Dehydration is often the cause, as is alcohol consumption. Outdoor music festivals, where alcohol consumption is high, are places of high heat stroke risk because people are standing in the sun all day while actually dehydrating themselves by consuming alcohol. Victims of heatstroke may become confused, nauseous, light-headed, or have a headache. Without treatment, heatstroke can cause damage to the brain and other organs, or even cause death. Treatment of heatstroke includes rehydration and cooling off. This can be done quickly with shade and air conditioning, but also with a cool water bath or damp cloths in the armpits, forehead, and neck. Although the immediate treatment is simple, an ambulance should be called or the victim should see a doctor due to the serious or even fatal effects that heat stroke can have. As always, the best treatment is prevention. Sunburn, alcohol, and certain medications all impair the body’s ability to regulate temperature. Always wear sunscreen when outside for long periods of time and avoid alcohol consumption before physical activity or even just being outside in the heat for long time. Alcohol consumption is often the cause of heatstroke at outdoor sporting events such as NFL or college football games. The stadium setting of these games adds to the often-hot weather. Another common cause of heatstroke is being in a car that is parked in the sun on a hot day. This has accounted for many deaths among children but is not safe for anyone as the car actually becomes hotter than the outside temperature, and does so quickly.

People who are at risk of hyperthermia and heatstroke are athletes, people who work outdoors in heat, overweight people, and people who have trouble staying hydrated (Calvin, 2012). These people should always try to stay hydrated, wear loose-fitting clothing that allows for sweat evaporation, know how to contact the local emergency services in case of any heat related emergency, and plan their physical activity based on the weather. Athletes may prefer to do their workouts in the morning or evening when it is much cooler and they are at less risk of hyperthermia. Youth and elderly are also at an increased risk of heat stroke. It is important for youth participating in youth sports leagues to remain hydrated, but this responsibility often falls on the parents as the youth don’t realize the importance of staying hydrated or recognize when they are becoming dehydrated.

Lissoway, J. (n.d.). Heatstroke. Retrieved June 16, 2015, from (Links to an external site.)-poisoning/heat-illness/heatsroke?qt=heatstroke&alt=sh

Calvin, K. (2012, June 27). Hyperthermia: Too hot for your health. Retrieved June 16, 2015, from

CDC. (n.d.). Heat illness among high school athletes --- United States, 2005-2009. Retrieved June 16, 2015, from (Links to an external site.)