Caffeine does not dehydrate you. Many claim it to be a diuretic, but there's little evidence for that. Most reports find that it doesn't increase water loss unless you're taking in a huge amount of it very quickly. (I haven't looked into alcohol as much--since coffee is my main vice--but this IOM/NAS study I'm looking at here suggests that the overall diuretic effect of alcohol on a person's hydration is not significant. [It is directly after the caffeine section that I'm gonna quote, if you're interested.]) But those coffees and sodas are still mostly water. They're getting plenty of water. Probably not the healthiest overall choice of beverage to be downing each and every day, but in terms of hydration the coffee- and soda-slammers are fine.
From pages 133-134 of that study:The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide. The report did not specify exact requirements for water, but set general recommendations for women at approximately 2.7 liters (91 ounces) of total water -- from all beverages and foods -- each day, and men an average of approximately 3.7 liters (125 ounces daily) of total water. The panel did not set an upper level for water.
Caffeine is one of three methylxanthines found in foods; it is naturally present in coffee, teas, and chocolate, is added to colas and other beverages (IOM, 2001a), and is a component of many medications (Passmore et al., 1987). It is estimated that 20 to 30 percent of Americans consume more than 600 mg of caffeine daily (Neuhauser-Berthold et al., 1997). The other two methylxanthines, theobromine (found in chocolate) and theophylline (found in tea), demonstrate some, but not all, of the pharmacological effects of caffeine (Dorfman and Jarvick, 1970).
It has long been thought that consumption of caffeinated beverages, because of the diuretic effect of caffeine on reabsorption of water in the kidney, can lead to a total body water deficit. However, available data are inconsistent. As early as 1928 it was reported that caffeine-containing beverages did not significantly increase 24-hour urinary output (Eddy and Downs, 1928). Caffeine-containing beverages did not increase 24-hour urine volume in healthy, free-living men when compared with other types of beverages (e.g., water, energy-containing beverages, or theobromine-containing beverages) (Dorfman and Jarvik, 1970; Grandjean et al., 2000).
Conversely, in a study in which 12 individuals who normally consumed caffeinated beverages were required to abstain from all methylxanthine-containing foods and drugs for 5 days and who were then were given 642 mg of caffeine in the form of coffee, 24-hour urine output increased by 0.75 ± 0.53 L, a 41 percent increase (Neuhauser-Berthold et al., 1997). Given that the study design did not evaluate habitual intake, it is difficult to determine the extent to which this large amount of caffeine would impact total water needs on a chronic basis.
In an earlier study, the effect of caffeine intake on urinary output was evaluated in eight men who were asked to consume four cups of coffee or six cups of tea/day (providing approximately 240 mg of caffeine/day) for 5 days prior to data collection and then to abstain from caffeine 24 hours prior to data collection (Passmore et al., 1987). The subjects were then given various doses of caffeine (45, 90, 180, or 360 mg) on the study day. Cumulative urine volume 3 hours after consuming the test dose was increased significantly only at the 360-mg dose of caffeine. This is equivalent to four cups of regular brewed coffee (USDA/ARS, 2002).
Caffeine can induce hemodynamic effects not directly related to fluid balance. The acute pressor effects (e.g., vasoconstriction, palpitations) of caffeine consumption are well documented; however, in a review of the relevant literature, there was no clear epidemiologic evidence that habitual caffeine consumption leads to hypertension (Nurminen et al., 1999).
In aggregate, available data suggest that higher doses of caffeine (above 180 mg/day) have been shown to increase urinary output, perhaps transiently, and that this diuretic effect occurs within a short time period (Passmore et al., 1987). Whether or not caffeine ingestion at high amounts leads to a total body water deficit is uncertain (IOM, 2001a), although some have tried to develop a predictive model of water needs based on the limited data available (Stookey, 1999). Hence, unless additional evidence becomes available indicating cumulative total water deficits in individuals with habitual intakes of significant amounts of caffeine, caffeinated beverages appear to contribute to the daily total water intake similar to that contributed by noncaffeinated beverages.
You, Never? Did the Kenosha Kid?
I was dehydrated for about a month a few years ago. I was working outside during the summer months and didn't realize I wasn't hydrating properly. I was drinking water, but not enough. I started getting really sick, light headed, had throat and swallowing problems, felt tired all the time. Started drinking a big gatorade after work every day and it cleared up within a day. I was just glad I didn't have cancer like I thought I did. Stupid WebMD...
Spoke to Rick Carlisle yesterday afternoon, the day after the Mavericks head coach got light-headed and collapsed into a dead feint at practice. Following a battery of hospital tests, which were negative, he was back on site an hour later.
Still, just to be safe and supposedly to get some rest, Carlisle didn't accompany the team to Palm Springs, Calif., for last night's outdoor exhibition against the Suns. Assistant Dwane Casey took over with Rick scheduled to return for tomorrow night's home game against the Cavaliers.
I thought maybe Carlisle had a bad reaction to Mark Cuban telling him he'd just traded for Ron Artest.
"Nice try," Carlisle said. "But I love Ron.
"This is what happened: I usually take my daughter to school around 7:45 and then I go for a workout. Afterward I usually eat a Balance Bar and drink a Mountain Dew. [On Friday] I had three and three."
Hopefully his daughter (and players) has a healthier morning intake than that.
"Had I drank some water this probably wouldn't have happened," Carlisle conceded before heading to the gym for a workout that includes drinking lots of water.
Last edited by Unclebuck; 10-11-2010 at 08:30 AM.
Last edited by Unclebuck; 10-11-2010 at 08:31 AM.
You, Never? Did the Kenosha Kid?
Soup is right. The old adage of 8 glasses of water per day has never been proven in any study, it just become an old wives tale passed around. A few years ago a doctor whose name I don't recall was looking into this and found no studies that attempted to support it at all. Only a misunderstanding of the overall required water intake which 100% includes foods and caffeinated drinks making the supplement of 8 additional glasses way beyond a normal amount.
edit: found it at Scientific American
It includes this excerpt (more than one doctor is quoted in the article)
If you've stopped urinating or if your urine is getting extremely dark, then that's a sign you are getting dehydrated. Conversely you really shouldn't be drinking too much water to the point that you're urine is completely clear.Barbara Rolls, professor of nutrition sciences at the Pennsylvania State University, disagrees. Her studies, she says, "found no evidence that people are chronically dehydrated."
Also it is very possible to OVERHYDRATE your body, resulting in brain damage or coma.
Usually you must have a kidney condition or other issue, but a healthy adult can get to that point by drinking 2 gallons of water in a single day. And it's actually easier if you exercise a lot and replace the sweat with straight water.
A woman running the 2002 Boston marathon died of overhydration which is mentioned in this article original printed in UltraRunning magazineSince the brain is the organ most susceptible to overhydration, a change in behavior is usually the first symptom of water intoxication. The patient may become confused, drowsy, or inattentive. Shouting and delirium are common. Other symptoms of overhydration may include blurred vision, muscle cramps and twitching, paralysis on one side of the body, poor coordination, nausea and vomiting, rapid breathing, sudden weight gain, and weakness
And discussed here as well
And from Wiki...
Medical personnel at marathon events are trained to suspect water intoxication immediately when runners collapse or show signs of confusion
Last edited by Naptown_Seth; 10-11-2010 at 11:50 PM.
Blood sugar could the culprit. I've had a few fainting spells. Not fun.
There are two types of quarterbacks in the league: Those whom over time, the league figures out ... and those who figure out the league.
I always thought clear urine was healthy. That's at least what I had heard. Interesting.
I'm big on the water though. I never go without my water bottle.
However, the oint is still valid. Being over hydrated is bad.
That said, that is harder to reach then you might think.
It is still bad if you ever get to think point. I ran with track with a young man who ended up going professional in track, and I remember how shocked all us us were when someone (a young college guy I think) died from over-hydration in one of the marathons.
This happened quite a few years ago now, but it left such an impression on me that I still remember it to this day:
By Del Quentin Wilber and David Brown
The entire article is a good read, but that part touches on what has been mentioned in this thread so far.At some point, McBride told an instructor that he had consumed perhaps as much as three gallons of water contained in a backpack he was carrying. Bicyclists often drink water through a tube connected to a bladder contained in such packs.
Officers said that McBride seemed to be recovering as he sat out the exercise. When another officer hurt his knee, police summoned an ambulance. The paramedics noticed that McBride was convulsing and continuing to vomit. They took him to Washington Hospital Center, where he died about 1:30 p.m. yesterday.
Many experts believe hyponatremia has become more common in recent years. More people are engaging in endurance events, such as marathons, that last many hours and during which participants are urged to drink water.
To anyone that's suffered a heat stroke before...that's something scary as ****. You never do any kind of sports activity after that without lots of water onhand.
I suspect most people that over-hydrate generally have seen or experienced what severe dehydration can do, and mistake the warning signs of consuming too much water with the signs of not consuming enough...
Last edited by Kstat; 10-12-2010 at 07:20 AM.
OK, I never suggested that anyone should drink too much water, nor did I suggest anyone drink "8 glasses a day" But I stand by everything I've posted in this thread. As with everything use common sense.
I probably drink about a gallon of water a day between water and juices and I haven't died yet. j/k - not counting the maybe 1 - 12 once soda I drink a day.
if you are a 115 lb women, no I don't suggest you drink a gallon of water every day. Once again a little common sense.
Last edited by Unclebuck; 10-12-2010 at 08:35 AM.
A bird in the hand is worth two in the bush.
Or throw in a first-round pick and flip it for a max-level point guard...
You, Never? Did the Kenosha Kid?
On the urine thing - I think totally clear urine just means that you've had more water than necessary, and so your body's flushing it out of your system. More than likely you're not anywhere near overhydrating (especially if you are, you know, peeing at the moment), although I do think having too much water in your system can impair kidney function by a very slight %. (Nothing I'd worry about though.)
You, Never? Did the Kenosha Kid?