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I know very little about anatomy but I have a memory from somewhere that the more yellow coloured one's urine is the more dehydrated one tends to be.

I have another memory that you can drink too much water and pass valuable electolytes (??? I am sure it wasn't an Electrolux, anyway. Passing an Electrolux would surely be an indicator of a severe bladder infection I suspect).

1 How much water should be taken each day by an average adult?
2 Is it true that around 60% of Australians are dehydrated at anyone time?
3. Why do diabetes get thirsty and why do diabetics need to urinate so much
at night?

Dr Chris could probably answer this q better that I, but I will tell you what I know, off the top of my head.
I can look it up if you want more detailed info.

The glomeruli (the cells in the kidneys that filter the urine) selectively reabsorb water. The body is trying to achieve what is called homeostasis.
So all the waste products are in less water.
Additionally if you take certain drugs or vitamins that will also darken the colour of urine.

If you know you have drunk an adequate amount of fluid and only pee out a fraction of what went in and its very concentrated, then drink more.. A lot of men can get cystitis quite easily. Cigarette smoking also causes bladder irritability from the breakdown of nicotine because it sits in the bladder all night and Bladder Ca (Cancer) is mostly caused by smoking.

Electrolytes are such things as sodium, potassium etc.
Yes there are these things, waste products of digestion, blood break-down products, hormones and drug by-products all found in the urine. >

eight glasses.
About 2 litres.
If you smoke, then double it - or better still, quit smoking.

One is a metabolic disorder, the other a disorder of metabolism. NOT the same thing.

Diabetes Insipidus relates to an inadequate amount of ADH (Anti Diuretic Hormone) released from the pituitary gland in the brain. Deficiency of this hormone results in excessive thirst and the passage of huge amounts of urine that has NO glucose in it. A drug called Vasopressin usually fixes this.

Diabetes Mellitus (often called 'SUGAR DIABETES') relates to an inadequate amount (or no) insulin being produced by the pancreas.
Therefore carbohydrates cannot be properly metabolised and there are problems with protein and fat metabolism as a follow on.
There are accumulations of the end-products of metabolism ketosis, acidosis etc..... Because the diabetic has excess glucose he can't use (hyperglycaemia)
By the way hypEr means high - hypO means Low - I hate it when people say Hypo and mean high ---

the body in an effort to achieve homeostasis starts trying to flush it out. So glucose spills over into the urine. With excess fluid loss - it upsets the electrolyte balance of the body (that would take ten pars on its own) and see homeostasis again..... Over time, raised fat and sugar levels can damage blood vessels tissues and organs.

People get NOCTURIA (needing to pee excessively at night) for various reasons, the most common of which is loss of bladder tone - the bladder is only a muscle - which is common in aging. Diabetics (DM) may need to urinate at night for several reasons including a certain amount of water retention, that is alleviated by rest, hyperglycaemia, age and altered kidney function such as nephropathy.

I should also have mentioned that you lose water with breathing and in perspiration. Naturally in summer and in excessive heat or exercise, urine can become concentrated.

If you have more fluids going in than coming out and other problems of fluid retention, like swollen ankles, a swollen abdomen or other symptoms, then get to a doctor quick!

Melissa hasn't actually answered the question, so I will.

Yes it is possible to drink too much water and lose excessive sodium. This sometimes occurs in ultramarathon athletes and others (e.g. soldiers) who engage in vigorous physical work in the heat and sweat profusely (I have measured sweat rates up to 1.5 L/h in soldiers on patrol in Far North Queensland in February).

Sweat includes sodium (among other electrolytes). If only water is drunk, sodium losses can be so high that 'water intoxication', also called 'hyponatraemia' occurs. One solution is to drink a dilute salt solution (e.g. 1 g of salt per L of water) rather than pure water. This is why sports drinks are solutions of carbohydrate and electrolytes--the carbohydrate is there largely as an energy source, the electrolytes are there to replace losses in sweat.

Melissa, you were on the list two months ago when Toby and I had a detailed discussion on this. The idea that '*everone* should drink 2 L of water per day is not sound. As I pointed out in June, a person's requirement for
water depends on many variables--particularly the climate and how physically active the person is. There is no 'magic number' of glasses appropriate for everyone.

However, it is also true that people would be well advised to drink less beer, coffee, and so on, and concomitantly increase their intake of water.

Well, if you really don't know, on what grounds do you consider that this is probable? :-)

I also don't know, and I'm not sure how anyone could know. Certainly, chronic hypohydration (the state of less-than-optimal total body water) is considered to be rife among Australian athletes. And from studies I have
conducted on soldiers in hot climates, usually about one-third are hypohydrated (defined as specific gravity of urine greater than 1.030) at any one time. But this is nowhere near the claimed 60% for the general population.

Sent: Thursday, June 06, 2002 7:53 PM Subject: How much water should you drink?

A few weeks ago we had a lively discussion on whether or not *everyone* should drink eight glasses (~2 L) of water per day.

An argument against this is provided in the message below my signature block (only relevant excerpts are shown). NB, 'half a (US) gallon' of water is about 2 L.

Water is necessary to prevent overheating of the body; for fecal, urinary, and perspiratory excretion; and for bodily chemical reactions of numerous kinds. Environmental and physiologic conditions can greatly affect how much water the body loses. For example, in residents of hot climates, perspiratory water losses generally are much more than in residents of temperate regions. Exercising increases such water losses. So does fever. Although metabolism produces some water, nearly all of the water in the human body comes from food and beverages. Solid foods can provide a goodly proportion of one's water requirement. In their original states, most foods contain at least a little water. And some foods-particularly fruits and vegetables-are more than 90 percent water by weight.

Some guides not only specify how much water one should drink but also state which beverages are to be regarded as contributors to one's water requirement-e.g., noncaffeinated beverages. The advice concerning noncaffeinated beverages stems from the well-established finding that caffeine is a diuretic-i.e., it tends to increase the production and excretion of urine. Although as such caffeine is mild, some guides suggest that drinking eight ounces of a caffeinated beverage requires consuming the same volume of a noncaffeinated beverage. Such guidelines are far from accurate.

A 1997 issue of Annals of Nutrition and Metabolism included a report of a study in which young men had abstained from ingesting caffeine and similar compounds for five days and had then drunk the equivalent of six presumably 6-ounce cups of coffee, thus ingesting over 600 mg of caffeine. The researchers found that partially substituting caffeinated coffee for other beverages had resulted in the subjects' passing, on average, 753 milliliters more urine than they had voided when they had consumed water instead. Evidently, this volume is roughly 69 percent of that of the caffeinated coffee the subjects drank. But findings from a more recent study, published last year in the Journal of the American College of Nutrition, suggest that in the study described above the five-day absence of dietary caffeine had significantly contributed to the reported increase in urine volume. In the newer study, 18 healthy young men drank either water alone or water plus other beverages-including coffee and caffeinated colas-in assorted combinations. The researchers found that urine volumes had not varied according to whether the subjects had consumed caffeinated or noncaffeinated beverages. They said the reason their findings differed from those of the earlier study was probably that their subjects had regularly consumed caffeinated beverages daily until the experiment. Other investigators have likewise suggested that the body adapts to caffeine intake so that eventually it has little or no effect on water losses. The studies referred to above had few subjects, and their findings apply mainly to healthy men. But these findings reinforce the conclusion that for many Americans--particularly those whose diets are high in fruits and vegetables--drinking a half-gallon of water is superfluous.

See also <http://www.acsh.org/press/editorials/water052902.html>

On 3/10/2002, Chris Forbes-Ewan wrote:

Below… is the detailed FAQ--on fluids for hydration--compiled by the Nutritionists Network ('Nut-Net'). This (and the summary answer) will soon join the other Nut-Net nutrition FAQs available through the Nutrition Australia website:

www.nutritionaustralia.org

The following series of questions and answers address the quantities and types of fluids recommended to maintain appropriate body water levels, and to assist in weight control.

1. How much fluid should I drink each day?

There is a common perception that 'everyone should drink eight glasses of water per day'. Assuming that a typical glass has a volume of ~250 millilitres (mL) this would mean that everyone should be drinking about two litres (2 L) of water each day.

Although it may be true that many people would benefit from drinking more water, it is not possible to specify a quantity that is appropriate for everyone. The requirement to drink water depends on how rapidly it is lost from the body, and also on how much water is obtained from our food. Nearly all 'solid' food actually provides some water--for example, most fruits and vegetables are about 90% water by weight, and we also obtain some water as a result of metabolising protein, fat and carbohydrate.

Water is lost as 'insensible' (i.e. unnoticed) perspiration through the skin, as liquid water in sweat and urine, as water vapour in the breath, and as a component of faeces. Of these, the most variable is the amount of water lost as sweat.

Sweat rates vary enormously. For example, a rate of 3.7 L/hour was measured in Alberto Salazar, the winner of the 1984 Los Angeles Olympic Marathon, which was conducted on a hot summer's day. This means that if Salazar had drunk only 2 L of water during the race, he would have undergone a significant level of dehydration before the race was even half finished. Although this sort of sweat rate is at the high-extreme level, it does illustrate that generalisations about water requirements can be quite misleading.

How much water you need will depend on many factors, including the weather, how much physical work you do, the composition of your diet, and your state of health (e.g. the requirement is much greater during fever, when undergoing treatment for kidney stones, and for people who have a tendency to suffer constipation).

It is also advisable to drink more water than usual in dehydrating environments. These include offices where air-conditioning produces dry air; hot/dry climates (such as occur in much of central and northern Australia); and long-distance flying. In the case of flying, increased water consumption is recommended not only for good hydration status, but also as a preventive measure--along with plenty of physical activity--against deep vein thrombosis (DVT).

2. How can I tell when I need to drink?

For most people, thirst is a pretty good indicator of the need to drink (although it isn't perfect in all situations, as described in detail below). For people who do not readily experience thirst, other relevant indicators include infrequent urination, low volume and dark colour of urine. If you do not have to urinate every few hours, and the urine you produce is much darker than usual, you have probably started to dehydrate.

3. Does it matter what sort of fluid I drink?

For most people water is the most appropriate rehydration fluid under all but exceptional circumstances. Water provides no kilojoules, so it is ideal as the thirst quencher if weight control is an issue (as it is for most Australian adults and an increasing number of children. For more information on obesity, see the FAQ in this series, available at:

http://www.nutritionaustralia.org/Food_Facts/FAQ/activity_and_weight_faq.asp

Water also has no detrimental effect on the teeth, because it contains no sugar and is not acidic (and if it is fluoridated, it is actually beneficial to teeth).

By way of contrast, many carbohydrate-containing drinks (such as sports drinks, some fruit juices and carbonated soft drinks) not only contain sugars (which increase the risk of tooth decay) but are also quite acidic. People who continually 'bathe' their teeth in sugary, acidic drinks are at high risk of damage to the tooth enamel because of acid erosion.

There are still valid reasons for drinking some carbohydrate-containing fluids. Fruit juice, for example, is a major source of vitamin C in the Australian diet, and sports drinks are thought to be superior to water for rehydration during hard physical work (or exercise), especially in the heat, as described in greater detail in the answer to question 5, below.

Some fluids are not really suitable as the primary sources of water because they contain 'diuretics' (substances that stimulate urine production). Most alcoholic beverages and drinks with high levels of caffeine come into this category. Although the body can cope with moderate quantities of alcohol and caffeine, excessive intakes can have negative effects on hydration status. This applies especially in people who are not used to drinking large volumes of these beverages. For more information on one such beverage, high-caffeine energy drinks, see the FAQ available in this series at:

http://www.nutritionaustralia.org/Food_Facts/FAQ/caffeine_and_energy_drinks. asp

And of course, excessive alcohol consumption also has short-term adverse effects on judgement and coordination, and long-term adverse effects on health.

However, it is worth keeping mind that small quantities of caffeine are not associated with health risks, and at least one caffeine-containing beverage, tea, is also a useful source of antioxidants, which are thought to be health-promoting. For more information about tea and health, see the FAQ in this series, available at:

http://www.nutritionaustralia.org/Food_Facts/FAQ/tea_and_heart_disease_faq.a sp.

And the occasional cup of coffee, although not thought to have any particular beneficial effects on health, provides a 'pick-me-up' boost to mental performance through its caffeine content.

4. Is bottled water better than tap water?

In the majority of Australian municipalities, tap water has been treated to make sure that it is clear, free of harmful bacteria, and (in many cases) it has had fluoride added for better dental health. There is nothing 'wrong' with bottled water, but in most cases, you are paying a lot of money for a product that is no better than the water available at no (or very low) cost from your kitchen tap.

5. Are there circumstances in which I should drink fluids other than water?

Fluid intake should be increased when you are exercising or working hard in the heat, and under these circumstances there is good reason to consider using carbohydrate-electrolyte solutions (e.g. 'sports drinks'). It is also appropriate to start drinking even before you feel thirsty, because the sense of thirst may not be activated until well after dehydration has begun.

When sweat rates are high, sports drinks are valuable because they will reduce the likelihood of 'water intoxication' (also known as 'hyponatraemia'). Water intoxication can occur when profuse sweating continues for many hours, with water as the only fluid consumed. Under these circumstances, the salt lost in sweat may not be replaced unless foods containing sodium are consumed or you rehydrate with sports drinks (such as those commercially available). As an alternative, a recipe for an inexpensive, home-made sports drink is provided in an FAQ in this series, available at:

http://www.nutritionaustralia.org/Food_Facts/FAQ/sports_drinks_faq.asp

But remember that commercially-available sports drinks are not only sugary but also acidic, and so can cause considerable damage to teeth if they are consumed inappropriately. With regard to dental health, it is preferable to drink a fairly large volume of carbohydrate-containing fluid (e.g. 500 mL) every 30-60 minutes, and follow this with a mouthful (or two) of plain water to wash the sugar and acid from the teeth, rather than drink small volumes frequently.

Also with regard to fluid intake and dental health, it is advisable to drink fluoridated water and ensure adequate calcium intake (e.g. by drinking three glasses of milk, preferably low- or reduced-fat, or eating an equivalent quantity of milk products daily) to ensure that there is enough calcium in the diet for 'remineralisation' (i.e. repair) of tooth enamel.

6. Are there circumstances when I should limit the amount of fluid I drink?

Under certain medical conditions, some people may need to limit their fluid intake. This may apply if cardiac, renal (i.e. kidney) or liver failure has previously occurred. Your doctor or dietitian can advise you about appropriate levels of fluid intake if you suspect that any of these apply to you.

7. Will drinking water with a meal help with weight control?

There is a common belief that drinking several glasses of water just before eating, or during a meal, will help to reduce food intake, because the water helps make the stomach feel full.

There is actually little or no scientific evidence in support of this belief. In fact, it appears that eating high-moisture foods (rather than drinking water with or before a meal) does a better job of reducing the amount of food eaten. For example, one recent study found that having a bowl of soup before main course led to an overall 16% reduction in kilojoule intake compared to not starting with soup. Vegetables and fruits are other high-moisture foods that should help with weight control when eaten with meals (or as between-meal snacks), by making the stomach feel full.

8. Is it true that drinking very cold water will help with weight control by increasing metabolic rate?

This idea is based on the belief that heat taken from the body by drinking cold water must be replaced by heat generated as a result of increased metabolism.

There is little, if any, evidence in support of this belief. When the body loses a small amount of heat (e.g. from drinking cold water), rather than leading to increased metabolic rate, it is far more likely that heat-conservation mechanisms will be switched on. Foremost among these is a partial 'shutdown' of the flow of blood to the skin. This means that less heat will be lost to the environment, allowing normal metabolism to gradually bring the body's temperature back to normal. Therefore, drinking cold water will probably have little effect on metabolic rate.

It has also been shown that, at least when working hard in hot climates, many people have a tendency to drink less water if it is very cold (e.g. 4 degrees C) compared to water that is simply 'cool' (e.g. about 15 degrees C). Because dehydration is a potential cause of heat-illness, it would be preferable under these conditions to cool (but not chill) drinking water.

9. Do people on low-salt diets need as much water as other people?

As recommended in the Dietary Guidelines for Australians, many people have substantially reduced their intake of salt, largely for the prevention or treatment of 'hypertension' (high blood pressure).

Because most of the excess salt in the body has to be flushed out with water (as urine), lowering salt intake can significantly reduce the quantity of water you need to drink. However, most of our salt intake comes from processed food, so eliminating cooking salt and table salt, but making no other changes to your diet, will have only a slight effect on your water requirements. But if you strictly follow the Dietary Guidelines, and the only processed foods you eat are 'low salt' (sodium content less than 120 mg/100 g), your requirement for water may be reduced by up to half a litre (about two glasses) per day. The exact difference would depend on the size of the change (how often you had been eating high-salt foods such as ham, bacon, olives, smoked oysters, pretzels, pizza, processed cheese and so on) before you eliminated these from your diet.

No, I hadn't heard that idea, at least not from health professionals.

As you are obviously aware, water from food is released during digestion and most of it will be absorbed from the small intestine. If it were all (or even mostly) to go to the large intestine, our faeces would have to be extremely high in water, and we would need to have many bowel movements per day. I wonder if this had ever occurred to your nurse!

Although I don't like disparaging or disagreeing with other health professionals, you might like to print the FAQ and show it to your nurse. Perhaps she is open to being convinced (but I wouldn't bet on it--there are a lot of self-appointed 'experts' out there).

It's too late for this iteration of the FAQ, but it could be addressed in a revised version. Unfortunately, that won't be for a couple of years, probably.

On 27/6/2003 Chris Forbes-Ewan posted:

Last year a rather acrimonious debate took place on this list about the need (or otherwise) to drink eight glasses of water a day to maintain adequate hydration status.

All those people who haven't been drinking eight glasses of water a day--and who are wondering if they actually shrivelled up and died of dehydration many years ago without noticing--can stop wondering. The issue of Nutrition News Focus shown below my signature block provides pretty good evidence that they are probably still alive (and adequately hydrated).

<snip>

June 25, 2003
NUTRITION NEWS FOCUS
"Nutrition news is important. We help you understand it!"

Today's Topic: Water Balance Without Water

A mythology that people must drink water to hydrate themselves has existed without evidence for years. A new study shows that plain water is not needed as long as enough fluid is obtained from food and drinks.

Twenty-seven healthy men consumed one of two diets for three-day periods in which they were studied in a lab setting. The first included plain water while the second omitted it, relying on only foods, orange juice, diet soda, and coffee for fluid. None of the nine measures of hydration were affected. The study appeared in the April 2003 edition of the Journal of the American College of Nutrition.
< http://www.jacn.org/cgi/content/abstract/22/2/165 >

HERE'S WHAT YOU NEED TO KNOW:
Despite the conclusion that "everyone knows" water is essential and advertising by the bottled water industry, this study shows that plain drinking water is not needed as long as adequate fluids are consumed either as drinks or in food. The people in this study were sedentary and indoors; those active outdoors need more fluids and water is still an excellent choice. Children and elderly have a less acute sense of thirst than others, but the lie that you are damaging yourself or near death if you become thirsty is simply based on no facts.

Excellent. I have a tea in the morning before I go to work and do not get anything until 3 in the afternoon - if I have a drink in that time I have to go to the loo which is near impossible when I have a bunch of kids in the mangroves. Leaving the kids alone also contravenes the rules for duty of care so I'm kind of stuck. I also have a REALLY large bladder and the ability to hold on for extraordinary amounts of time.

(I was once told by a babysitter that if we didn't go to the loo when the need arone it would be reabsorbed back into my body and poison me!)

Gary-Peter Dalrymple wrote:

I have just recieved my copy of the journal of the Australian Skeptics (or should I say that I have just recieved what I understand to be my copy of what I understand to be the Australian Skeptics).

In the current issue it has an article from a retired (Queensland) cattle country doctor specifically on dehyration complications caused by minimal daily liquid intake.

There is also an article on the Channel 31 (Sydney only?) Science program.

Subscribe or check your local library for a copy.

There might also be stuff on their web pages.

> All those people who haven't been drinking eight glasses of water a day--and
> who are wondering if they actually shrivelled up and died of dehydration
> many years ago without noticing--can stop wondering. The issue of Nutrition
> News Focus shown below my signature block provides pretty good evidence that
> they are probably still alive (and adequately hydrated).
>

Chris Forbes-Ewan added, on 27/7/2003:

For those who are interested in recommendations on how much water or other fluids should be drunk each day, the recently-released Dietary Guidelines for Australians include the following source: http://www.nhmrc.gov.au/publications/pdf/n31.pdf

"Regular drinks replace water lost from the body during the day. In a mild climate an average person needs to drink about a litre and a half of fluids each day. In hotter parts of Australia much more may be needed to prevent the body becoming dehydrated.

Risks of dehydration

"Drinking too little fluid can lead to dehydration. In the short-term this may cause physical and mental tiredness. In the long-term, low fluid intake can increase the risk of developing kidney stones. For those people who have had kidney stones in the past, increasing fluid intake will help prevent them coming back. Scientific studies also indicate that plenty of fluid can help protect against cancer of the urinary tract - in the bladder, prostate and kidney. Tap water is also a good source of fluoride for strong teeth and bones.

"Young children and elderly people are more at risk of dehydration. Also, with increasing age, the sensation of thirst becomes weaker and people may drink less."

Advice is also given on the appropriateness of different fluids (water, milk, tea, coffee, alcohol and so on).

On a related issue, the potential for ill-health from overdrinking, e.g. during marathon running or other activity involving a high sweat rate, is addressed in a recent ABC Health On-Line article:

TOO MUCH WATER DURING EXERCISE CAN KILL (Health News: 18/07/2003)
http://www.abc.net.au/science/news/health/HealthRepublish_904374.htm

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Dehydration