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By Sarah Floyd
Water. If this word sends your saliva glands rushing then chances are it’s time to drink. Grab yourself a nice big glass of ice-cold H2O and refresh yourself as you read about the benefits of this miracle substance.
What’s all the fuss?
Seeing as how the first pseudo cells of life began somewhere in a primordial soup of water- at least according to many theories- it seems reasonable to conclude that water is the first and primary ingredient for a living organism. Chemically, water is unique in its ability to stabilize temperature, dissolve solutes, promote chemical reactions with its polar nature, and adhere to itself and other substances to greater affect than most other chemicals. All of these properties aid in the delicate balance that hold Earth within a state of symbiosis. The first ascent of organisms out of the water and firmly onto dry ground was a huge step in the evolutionary process because of life’s necessity for water. It required advanced methods of water retention and cell to cell communication that allowed the organism to recognize its dehydrated state and seek out a water source. For humans and other mammals, the kidneys were the answer to the first and the complex mechanism of thirst allowed the latter.
The problem for humans today is not whether we should drink water (we all know that extreme dehydration leads to death), but how much water we should drink. The common conception in this day and age is that each person needs an average daily intake of at least 8 eight ounce glasses a day, though lately there has been a scare about drinking too much (1). Some sites on the internet suggest carrying a water bottle full everywhere you go (15). Should people be counting their water glasses? Is drinking a lot of water really beneficial to health? To answer these questions, we first need to examine the mechanism of water control in the body.
THIRST AND THE KIDNEYS
Water is constantly in the processes of escaping the body, whether through respiration, urination, or sweat. Of the three mentioned, only urination can adequately be controlled by the amount of ions in comparison to water in the blood. The human kidney is a highly advanced organ that only allows what little water the blood can spare out of the body (13). Even so, water must still be consumed at a rate that equals water lost. In 1937, Alfred Gilman showed that drinking is triggered by the absence of water within cells (2). He did this by observing the effects on cells in a surrounding solution high in solutes impermeable to the cell membrane and a solution with solutes such as glucose that could readily cross the membrane barrier. The first solution with impermeable solutes caused cell dehydration when water left the cell to balance the new concentration of solutes in the outer compartment which in turn led to more drinking. The permeable solute solution showed little change because the solutes could readily move between the cell and the compartments surrounding it to balance composition and was not marked by drinking.
Scientists now know that the extracellular compartment (the boundary outside the cell) is very important in the regulation of thirst. If this compartment were to suffer from water loss, it would lead to reduced performance, circulatory collapse and eventually death (2). One significant extracellular ion regulator is sodium. Sodium is one solute that is impermeable to the cell membrane by cell regulation. When a person is already dehydrated, an increased amount of sodium pulls even more water out of the cell and results in further dehydration. However, if a person has drunk a large amount of water recently, increased sodium intake will prolong hydration by preventing the kidneys from taking too much water out of the body. Therefore salt with large amounts of water is not a bad thing and may actually be highly beneficial, especially for athletes.
WATER AND HEALTH: The Ultimate Miracle Drug
Health is a condition of balance and well-being within the body. The effects of water on health in general are hard to identify because so many factors influence the health of a human body. Studies have shown, however, that increased water consumption can be a good cure for many common health problems caused by factors other than virus and bacterial infection.
For example, one study of eighteen headache patients in the Netherlands by the Research Institute Caphri, all of whom suffered from migraines, shows a correlation between increased water consumption and headache relief. The eighteen patients were randomly allotted to two groups, one of which received only a placebo medication and the other which received both the same medication and a recommendation to drink 1.5 L of water a day. By the end of the 12 week study, the trial group had decreased their hours of headaches for every two weeks by 21 hours and decreased headache intensity on a visual analogue scale by 13 mm after having increased average water consumption by 1 L a day. The effects of the placebo medication were small (3).
Water has also proven helpful in treating recurrent abdominal pain and pancreatitis. The study was taken with adult cystic fibrosis patients from the Pancreas Disease Clinic at Emory University School of Medicine who were asked to drink plenty of water during the night and keep a journal recording their abdominal pain and intensity, pain medication, and amount of water ingested. The journals were started 3 months before increased water intake began and halted 3 months after. Doctor’s and emergency room visits were also recorded 1 year prior and 1 year after the study began. During the study both pain medication taken and hospitalization decreases once the patients began drinking more water (4).
Even human tolerance to +Gz acceleration forces has been shown to increase by drinking more water at the Military Institute of Aviation Medicine in Warsaw. Two hundred men were given water and forced to withstand G forces. The tolerance increased by 0.8 G for consumption of 14 milliliters of water per kilogram per person and by 1.1 G for 21 ml/kg. Scientists found that the plasma volume increased by 5.24% for 14 ml/kg and 6.98% for 21 ml/kg and used this information to conclude that the increase in blood plasma made the body more tolerant of +Gz acceleration (5).
Meniere’s disease is a chronic condition that affects the inner ear that leads to extreme dizziness, low-frequency hearing loss, and a feeling of pressure in the inner ear. Attacks, called vertigo, may be sudden and violent, but frequency and length vary from case to case (6). One small study by the Department of Otorhinalaryngology in the Kitasato University School of Medicine in Japan showed that drinking large amounts of water greatly lessened the vertigo attacks and improved hearing for several frequencies. The patients, eighteen in the treatment group, drank 35 ml/kg of water per day for more than two years and were compared to twenty-nine patients treated with the typical dietary and diuretic therapy. The control group only improved vertigo, and hearing for four frequencies was actually reduced (7).
For a pregnant woman already with huge amounts of pressure on her bladder, drinking more water is probably the last thing on her mind. However, a study by the Department of Obstetrics and Gynecology at Lis Maternity Hospital in Israel found that increased water consumption after only a week increased the amniotic fluid volume of women with low amounts of amniotic fluid, a condition known as oligohydramnios (14), by an average of 2% (8). The positive affects of oral hydration on pregnant women with oligohydramnios were echoed by studies at the Chiba University School of Medicine in Japan (9) and the University of the Witwatersrand in South Africa (10).
Hydration and Exercise
Exercise is a state of increased respiration and sweating, both of which lead to higher losses of water. Naturally, a runner or heavy exerciser should drink more water than the average person. One question people usually have about hydration and exercise is whether sports drinks count in fluid intake, and whether they are beneficial. The Defence Medical and Environmental Research Institute in the Republic of Singapore compared exercise performance of people who were given only water and people who were given a carbohydrate-electrolyte fluid replacement. They found that drinkers of the carbohydrate-electrolyte fluid had a slightly longer endurance time, increased frequency of completion, and less apparent stress than the drinkers of plain water. Their conclusion was that carbohydrate-electrolyte drinks increased the amount of glucose in the blood, though there were no differences in hydration levels (11).
Another problem commonly associated with hydration and running is hyponatremia. This is a condition where sodium drop to dangerously low levels in the blood because of too much water consumption (1). A group from the University of Cape Town Sport Science Institute of South Africa followed 117 runners of the Houston Marathon from 2000 to 2003 and found that 28% developed hyponatremia during the course of the experiment. These runners drank considerable more water that their counterparts, averaging 31.7 cups a day compared to 18.9 cups for nonhyponatremic runners. This study also concluded that female runners consume more water than male runners and are at higher risk for hyponatremia (12).
CONCLUSION: How much water should I drink?
Many people like to calculate the exact amount of water they need each day and stick to that number. If this is your method, take into account that lean body mass holds 70% water and fat holds considerably less (as low as 45%). The amount of water you need depends on your size, your caffeine, salt, and alcohol intake, and your level of daily exercise (13). The average man loses 2 to 3 liters of water a day or 8.45 to 12.68 cups (2). This sounds like a lot, but water taken from beverages with sugars and carbohydrates can also count because these molecules do not effect cell hydration, though they do count in calories which also effects health.
For those of you who hate the confinement of the eight by eight rule, let thirst be your guide. Nothing is wrong with drinking only when you’re thirsty because that’s how humans were made to be. As long as you stay in touch with your body, you’ll be fine.
Balance and moderation are the secrets to a healthy life. Though too much can cause problems as well, increased water intake in many cases restores balance to a body out of sync. As a result, headaches are healed, pain is relieved, and babies are born healthy and alive. The body sits ready and waiting to conquer the stresses of life that are to come. How ironic that the ultimate miracle drug comes from the kitchen sink.
1. “Study Cautions Runners to Limit Their Water Intake” (SCR) – The New York Times.
2. Symposia of the Society for Experimental Biology- Journal v. 54 2002
“Control of water balance in mammals” by R.J. Balment
3. “Increasing the daily water intake for the prophylactic treatment of headache: a pilot trial.” PubMed: 16128874
4. “Nocturnal Hydration- An Effective Modality to Reduce Recurrent Abdominal Pain and Recurrent Pancreatitis in Patients with Adult-Onset Cystic Fibrosis.” PubMed: 16957999
5. “Effect of water load in human body systems upon tolerance to +Gz acceleration.” PubMed: 2485611
6. “Symptoms and Incidence of Meniere’s disease”
7. “Water may cure patients with Meniere disease.” PubMed: 16885753
8. “Effect of 1 week of oral hydration on the amniotic fluid index.” PubMed: 12698777
9. “Effect of maternal hydration on oligohydramnios: a comparison of three volume expansion methods.” PubMed: 9764623
10. “Maternal hydration for increasing amniotic fluid volume in oligohydramnios and normal amniotic fluid volume.” PubMed: 11869566
11. “Water versus carbohydrate-electrolyte fluid replacement during loaded marching under heat stress.” PubMed: 16173217
12. “Hew TD.” PubMed: 15867557
13. Thirst. By B.J. Rolls and E.T. Rolls. 1982.
14. “Oligohydramnios: What you need to know.” http://www.marchofdimes.com/pnhec/188_1033.asp
15. “Drinking Water to Maintain Good Health.” http://nutrition.about.com/od/hydrationwater/a/waterarticle.htm
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