Holding back the tide – it’s alkaline, by the way

In which Dr Aust tries to keep things in proportion

A common feeling of those who write about pseudoscience is that one is a bit like King Canute, the man who was supposed to have ordered the waves to retreat.

For instance, for all that has been written about what a total con water ionizers are, people still sell them, and other people still buy them.

And for all that has been written about how “alkaline water” is a bunch of bullshit and a scam – including by me – there are still preposterous claims for its health benefits everywhere. Blogger Andrew Taylor just posted another such claim, which he says he got as a spam email. It is a particularly daft one as it talks about water being ionized, or separated, by their machine into “alkaline water” and “acid water”.

Now, this kind of stuff always claims “alkaline water” is good for you, and the email Andrew got is no exception:

“Alkaline Water being the healthiest drinking water available to us, because it will increase the pH of your body, detoxifies and has an abundance of anti-oxidants”

[Hmm. It can only have antioxidants in it if it has lots of dissolved organic material, actually. Not convinced lots of dissolved organic material is really something you would want in your drinking water. But I digress.]

Having read that boilerplate, but typically overblown claim – “the healthiest… detoxifies…” – I’m tempted to ask sarcastically whether the stuff cures cancer too. Depressingly, the people selling this are there already:

“Due to restrictions on regulating the things we can claim publicly, we can not say certain things, that’s why I want you to do your own research specially on the “C” word”

Sigh. As all too often, the hyperbolic general claims about “detoxifying” are just the scene-setting for the subsequent hint of something miraculous that will cure real, and serious, diseases. (It won’t, of course.) What this suggests is that the sellers are targetting their claims at the sick and desperate, as well as the “worried well”.

Now, remember also that this piece of sales pitch claimed to “separate” water into alkaline and acid fractions. While most quacks tend to claim routinely that “acidity” is bad for you, this email makes an extra virtue of the claimed “acid” water (which won’t actually be acid in any meaningful sense, but that’s another story) by claiming:

“The Acidic Water that is produced is a cleanser and is very good for skin conditions such as the eczema, cleaning vegetables, fruit etc”

Remarkable. No wasted water with Woo-water.

I am oddly reminded of a spa town in southern Spain where I once went for a conference years ago. The major product of the town was its bottled water, and the people in the hotel bar used to tell us how good it was for you. “Good for drinking. For your insides. Makes you healthy”. And if you didn’t like the taste, no problem: “Good for bathing in. For your skin. And for people with arthritis” Good inside OR out. Good acid OR alkaline. Just send money.

Anyway, faced with this daily tide of garbage, it is possible to feel rather like old Canute.

Except that…. the story (which is almost certainly apocryphal anyway) is not supposed to carry the meaning that Canute (or “Knut”, since Canute is an anglicization of Knut) really thought he could turn back the waves.

According to the story as commonly told, he did his commanding-the-waves routine as a lesson to his courtiers that he could NOT actually command the waves to retreat, even if they – the courtiers – kept buttering him up by telling him he was a great king, mighty and wise, could do anything etc etc.

Would that many modern leaders, whether political or in large organisations, were as aware of their own limitations.

Anyway, in the story Knut/Canute is presented as a man with a bit of insight, and not someone who would beat himself up if the tide refused to retreat on command.

Which brings me back to alkaline water. I wrote a post on this almost exactly three years ago (it went live on March 1st 2008) called:

What Could Be So Fine… As to be Alkaline (Warning: Irony)

The post has logged over 1200 “page loads”, so most days, on average, someone has at least had it open in a browser. Last month there were twenty-seven. I hope some of those people read it. I hope some of them found it useful, and that perhaps it helped to clarify for some of them why alkaline water is a scam.

And like the Knut of the story, I am not hoping for miracles. So I will settle for that.

Pro-reality activism soundbite – from the desk – UPDATED

In which Dr Aust embraces a small bit of activism, though without rising from a sitting position.

As some readers will know, following the damning (and admirably well reasoned) House of Commons Science and Technology Select Committee Report on Homeopathy, long-time Pro-Unreality campaigner David Tredinnick MP (noted, inter alia, for claiming his astrology CDs on expenses as “research materials”) put down an Early Day Motion. Said Early Day Motion, EDM 908, asks MPs to support the idea that local Primary Care Trusts (PCTs) – the main “gatekeepers” in the National Health Service of what treatments are acceptable – should continue to be able to contract for homeopathy services.

This EDM has attained a certain amount of fame online, with Ben Goldacre and other Bad Science and/or Pro-Rationality types (e.g. Professor David Colquhoun) noting that it gives you a quick way to tell if your MP really understands the concept of scientific evidence. Or as Ben more pithily puts it:

“Does your MP seriously believe in fairies and magic beans?”

Obviously at election time these issues come to have more of a significance – especially given the oft-expressed sentiment, which I have heard from quite a few of my friends and colleagues, that the main UK parties are so indistinguishable on many issues that it is hard to see any point which way you vote. This is especially noticeable on healthcare, as anyone who follows UK medical blogs like Dr Grumble and the Jobbing Doctor will know. I think I personally expressed this not so long ago as it being  “hard to get a cigarette paper between Labour and the Tories on their attitude to the NHS” (particularly their mystifying enthusiasm for more private sector involvement in UK healthcare, but that is a discussion for another time.)

Times Science Editor Mark Henderson wrote an interesting opinion piece a few days ago in which he argued that one could and should distinguish, regardless of political affiliation, MPs that were generally “pro-science”. The obvious implication would be that this might give one a reason to vote for a particular candidate, or at least to quiz all the candidates in one’s constituency on their position on scientific issues.

Now, when I looked at the list of signatories to Tredinnick’s EDM 908 I was rather disappointed to see my own MP, who is generally pretty sane on most things, on the list. So I sat down to write them a letter explaining my unhappiness. I should say that I have written to said MP a few times before, the issues that prompted me being:

– the attempt in late 2006 by some religious groups to blizzard schools with pro-“Intelligent Design” literature

– the May 2008  House of Commons vote on stem cell research (and time limits for termination of pregnancy)

–  the BCA v Singh case and more generally the campaign for libel reform.

So it seemed like about time for my annual letter to the MP. Anyway, here is what I penned and sent off last night.

——————————————–

Dear xxxxxxx

As one of your constituents I was disappointed to see that you had signed David Tredinnick MP’s EDM 908 on NHS support for homeopathy.

As a scientist, and the husband of an NHS doctor, I feel strongly that homeopathy has no place in the NHS. As my wife says, when other services – things like health visitors, and home occupational therapy services for people housebound with disabilties – are under threat due to financial shortages, it is indefensible to be spending money on placebo therapies. Even if the actual amount is small, it could be better used elsewhere. Funding homeopathy on the NHS has no place in the era of basing medical treatments on evidence.

Moving to evidence, from a scientific standpoint the EDM, like the evidence the homeopaths gave to the recent Science and Technology Select Committee Hearing on homeopathy, is misleading. In any discussion weighting scientific and medical evidence, the simple NUMBER of published results is not the most important thing. It is the quality of the data – things like the size of the trial (number of patients enrolled) and in particular a trial’s freedom from obvious biases – that counts. Simply totting up the number of trials is a bit like assessing the value of the ideas in a book by asking how many pages it has. The overall verdict on homeopathy is quite clear, and that is that it is no more than a placebo.

Mr Tredinnick does not appear to understand the idea of scientific evidence, and has a long history of bizarre pronouncements on health matters, such as commending astrology and suggesting it is worthy of consideration as a health intervention. His views on the subject of Alternative Medicine are regarded, by every doctor or scientist I have ever discussed them with, as utterly partisan and wholly at odds with the evidence.

The provision of homeopathy is often defended as a matter of “choice”. I should say that I am entirely happy that people CHOOSE to use their own money to visit a homeopath, in the same way that they can choose to join a health club, take a spa break, or patronise a fortune teller. It is clearly their right to do so. But funding such things from the public purse is something else.

Could I ask you to please re-consider whether you wish to support EDM 908.

Yours sincerely,

Dr Aust

—————————————————————————————-

I have so far received the form “received your email” reply from my MP’s office, noting that it is a very busy time so a proper reply may take a while. Given the imminent election they have more of a point than usual. But I will let you know when I hear anything, and add any replies below.

—————————————————————————————

UPDATE April 9th.

Hurrah! – I am gratified to see that my MP has removed their signature from the EDM.

Though I wouldn’t presume to claim the credit – I suspect s/he was getting admonished (or let us say “informed” )  by sceptical members of his/her own parliamentary party.

Meanwhile, to see the kind of crap that is going on in the NHS as it struggles, under political Diktat, to make cuts whilst simultaneously saying “there will be no cuts”, see here.

And fear not, the Peoples’ Medical Journal knows what is needed in healthcare. This tragic story manages to suggest it is the Tories, while this one suggests hypnotherapy. *sigh*

Off-topic PS: For those interested in the Daily Fail’s tragic-cancer-patient-can’t-get-drug-due-to-Labour-NHS-meanness story alluded to above:

(i) a response from Sir Michael Rawlins of NICE (I can’t quite tell if he is bemused, or angry, or both – though I suspect the latter) ;

(ii) note that the Daily Fail story quotes Karol Sikora. Enough said.

What could be so fine… as to be alkaline (Warning: Irony)

Just in case you weren’t confused enough about water, the Alt-oids (my new favourite word for Alt Health boosters) have another Health Mystification Message for you.

In a health context water is a simple story: I would summarize it as “drink clean tap water, or some other liquid, when you feel thirsty”.

However, there is more money in telling people water is a really complicated business, which is what the Alt-oids do. For instance:

“Water” they tell you solemnly “is ONLY good for you when it’s ALKALINE”

Hmmm.

This message has been around for a while, but it has attracted my attention anew as I spotted that one of the online AltMed retailers I occasionally check out is now pushing pH papers as a health aid.

Yes, pH papers. Little books of strips of a special paper that changes colour when you dip it in fluids of different pH (acidity / alkalinity). Apart from in school chemistry, you may have met these papers if you keep tropical fish, or Koi carp.

Now you can buy these papers to check quickly if your body has the appropriate acidity / alkalinity.

 

Er… no you can’t, actually.

You certainly can buy the paper, and test the pH of your spit or wee, which is what the sellers suggest. This will, however, tell you Sweet FA about your “body’s pH balance”.

Apart from anything else, spit and wee have left your body, at least as physiologists and doctors mostly view it. These are secreted fluids. They are just temporarily residing in a compartment which is surrounded by your body. But they are separated from the real inside of your body by a layer of cells, or sometimes several layers.

To test body acid-base status you would have to take an arterial blood sample (to measure your arterial blood gases) – and believe me, you don’t want to do that without a good reason. Especially since, no matter WHAT reading the pH papers give in your spit or wee, there is almost certainly bugger all wrong with your body acid-base status.

You would know if there was, because you would be feeling distinctly ill.

 

First the pH papers… then, the Water Alkalinizer^TM…!

Of course, the selling of the pH papers can be just the set-up for a bigger pay-off. This is that you are “too acid”, either because you ”eat acid foods” (a subject for a future post), or because you “drink water that isn’t alkalinized”.

The second of these is a real money-spinner. For example the company I mentioned that is selling the pH papers also sells water alkalinizing systems for anywhere between £ 449 and £ 1249 (roughly 900-2500 $ US). Some health food stores I have seen have these systems and use them to sell “alkalinized water” in bottles, or by the glass.

 

The summary word for all this is: bullshit.

And, to re-emphasise one of my recurring themes, based once again upon confusing you, and convincing you that something normal is BAD for you – the normal here being poor old unloved tap water.

The first, and most blindingly obvious reason, that this is tripe is as follows:

Pure water really doesn’t have a terribly meaningful pH value, and will assume the pH of whatever you mix it with.

So how do you get “alkaline” water?

Well, from small amounts of dissolved salts that “confer” and “hold” the pH (the relative acidity or alkalinity). “Acid rain” is acid because it contains small amounts of salts derived from dissolved acidic gases like SO₃ and NO₂.

But…. tap water contains rather little in the way of dissolved salts. And the pH of a sample of water can be changed easily – by mixing it with something with a different pH. Like a solution of stomach acid, the stuff your stomach keeps in there to kill any little bugs you swallow that might make you ill, and also to help digest your food.

Furthermore, simple high school / GCSE Chemistry tells you that the “alkaline water” line is a crock. Because the extent to which a solution “holds” its pH value depends on something called the buffer power, which depends specifically on those substances dissolved in the water that can ”buffer” pH. This is something that anyone who did GCSE Chemistry has not only heard of, but has often seen with their own eyes.

Scientists commonly use pH buffers to “set” the pH of solutions they use in experiments to get biological processes to work properly. You need the right pH for the reaction. Different buffer substances have different pH values (or ranges, more accurately) over which they are good at buffering.

In your body, the most important buffer system consists of the “pairing” of carbon dioxide (CO₂) and bicarbonate (HCO₃^–), both of which are closely controlled to keep your “body acid base status” constant and your internal body pH (in your blood, and in your cells) around 7.4 (slightly alkaline).

 

Back to buffering school

To explain buffering simply: Take a weakly-buffered solution, containing a small amount – say 1 mM (1 milliMole per litre, 10^-3 Moles / litre) – of a pH buffer substance, and with a pH of 7.0 (neutral). The pH of this weakly buffered solution will fall (go acid) if you drip a drop of strong acid – like HCl, hydrochloric acid – into it. The small amount of pH buffer can’t “defend” the pH of 7.0 very well.

In contrast, a solution of 20 mM pH buffer at pH 7.0 is much more strongly buffered – 20 times as much – and the pH will barely twitch if you drip in the same amount of HCl as in the last example. The pH buffer substance “buffers”- protects – the solution pH of 7.0.

This buffering can also be shown by doing the kind of titration lots of people have done as a school chemistry experiment . You take a solution of a pH buffer in a beaker, add a colour-change pH indicator (something that will change colour when the pH changes substantially from alkaline to acid, or vice versa) and titrate in acid or alkali from a burette. The more concentrated the buffer solution you start with in your beaker, the more acid or alkali you have to add from the burette to get the pH in the beaker to change. Typically you add some, and add some, and add some, and then finally the colour suddenly changes.

What is happening is that as you add acid (say) from the burette it is being “mopped up” by the pH buffer – so that pH only changes a little, and the colour doesn’t change.

Only when all the buffer in the beaker has been consumed in mopping up the added acid does a BIG drop in pH (acidification) occur. And that is when the colour changes.

This simple experiment, which is a kind of special version of the acid-base_titration done by literally millions of kids over the last half-century or more, is actually one of the keys to understanding how your body copes with acids and bases. But more about that in a later post.

From these buffer chemistry examples, it should be intuitively obvious that when you mix two solutions of different pH “more buffer wins”. If you mix a solution containing 20 mM pH buffer at pH X with an equal volume of a solution containing 1 mM buffer at pH Y, the final pH will end up near the starting pH of the 20 mM buffer solution. – pH X.

 

So why does this kick the “Alkaline water” scam into touch?

Well, water will rarely have more than 1-2 mM dissolved salts in it. The main salt that acts as a pH buffer is bicarbonate (HCO₃^–), derived from dissolved CO₂. Let’s say, for the sake or argument, that the water you drink has 1 mM HCO₃^– in it.

Your body fluids (all of them) usually contain about 20 mM HCO₃^–. So if I were to mix a litre of water at any pH with a litre of ANY “body fluid” at pH 7.4, the pH of the body fluid would barely be touched.

And there is actually about 45 litres of well-buffered body fluid in my 80 kg body, not one litre. You do the calculation.

In fact, changing the pH of your drinking water won’t even change the pH in your stomach, let alone the rest of you.

Your stomach juice is a rather special secreted fluid; it is a solution of 80-130 mM HCl (hydrochloric acid) and has a pH or about 1-2 (strongly acid). This is its normal pH – with or without your having drunk “alkaline water”. So the pH of the water you drink will not even make a noticeable difference to the acidity of your stomach contents, let alone your body acid-base status.

For this reason, the pH of the water you drink is completely and utterly meaningless. It has hardly any physico-chemical meaning, and it certainly has zero practical significance.

Unless, of course, you are gullilble enough to be conned by the advertising pitch of the “alkaline water” snake oil salesmen.

 

Previous water posts:

Part 3: Glug glug glug – why those eight glasses a day don’t have to be water – or eight

Part 2: Drinking water can be deadly (not) pt 2: the men in grey suits… are actually on the case

Part 1: Drinking water – or bathing in it – can be deadly (not)

Glug glug glug … why those eight glasses a day don’t HAVE to be water (or eight).

The super successful campaign to persuade people to drink vast amounts of bottled water really has two parts.

One part, which we have already talked about, is to persuade people that tap water is dirty and harmful, while bottled water is clean, pure and healthy – not to mention aspirational.

The other part is to persuade people that they have to glug down vast quantities of water – not just liquid, water specifically – every day to stay healthy.

This latter part, it turns out, is just as much of a crock as the first bit.

It is A MYTH. An Urban Legend, peddled in the media and on the internet, and repeated by word of mouth, so often that many people believe it is true.

The standard version of it, repeated ad nauseam, is “drink eight glasses of water a day”. So prevalent is this message that even rather good newspaper articles like this one, which squarely nail the giant bottled water sales-fest, trot it out without question.

Sometimes you are also told how big the glasses should be: “eight ounces”, which to us metric European types is just under 240 milliliters (ml).

Thus the advice is sometimes short-handed (especially in the US) as “8 x 8” or “8 by 8”.

BUT… it turns out there is a big, big, piece of bullshit floating in this glass of nostrum.

Wait for it…

Any fluid will do!

Yes, as trailed in the title, the fluid doesn’t need to be water.

Truly. The total amount of “fluid intake” being suggested here (1900 ml per day, so nearly 2 litres) is sort-of reasonable (though still anywhere from 10 to 50% above what scientists and doctors think of as the normal daily drinking requirement), but it can be ANY fluid. Everything that you drink counts.

Water. Coffee. Tea. Herbal tea. Beer (yes, beer). Wine (yes, wine).

But…. If you knew that, then you wouldn’t need to keep slurping down water. Not to mention buying it in handy bottles.

So why DO so many people carry on with the endless water-sipping?

Answer: Because they have bought the message.

But… why weren’t we told 8×8 wasn’t true? And where does 8×8 come from?

Here is where it gets interesting. No-one seems to know. The evidence that the “8 x 8” figure was totally unscientific has been around for ages. And to most scientists, the idea that “only clear water counts as fluid” is so transcendentally silly that they probably never thought anyone would be crazy enough to believe it.

But people clearly did. So perhaps some eminent scientist needs to review the scientific literature, and explain just exactly why all the legends peddled by what I call the “Hydrationistas” are nonsense?

Well, it has been done. You can find a comprehensive scholarly demolition of all the water myths peddled by the Hydrationistas in a review written by Professor Heinz Valtin for the American Journal of Physiology here.

Heinz what…?

Heinz Valtin is an Emeritus Professor of Medicine and Physiology, noted for his seminal research over 40 years on how fluid output from the kidney is controlled. He originally qualified as an MD (medical doctor) and is the author of three textbooks on kidney physiology. Valtin was Head of a well-regarded Physiology department in the US (at Dartmouth University) and trained many other notable kidney physiologists and nephrologists (kidney doctors) over the years.

Above: Heinz Valtin and furry friend

Valtin is probably best known in science for his work on the Battleboro rat. This is a rat strain which does not produce any vasopressin (anti-diuretic hormone) and thus cannot concentrate urine (vasopressin is the hormone, released in the brain when your body is a bit short of fluid, that signals to your kidney to reabsorb water extra-efficiently).

Brattleboro rats, lacking the signal hormone, cannot reabsorb water very efficiently and thus cannot produce concentrated (v. dark) urine. So they pee out lots (and lots) of dilute wee. They compensate for this by drinking bucket-loads – it can be the equivalent of 70% of their body wt a day – and the famous picture above shows a Brattleboro rat with a beaker containing its daily fluid intake. Brattleboro rats, which are a natural “vasopressin knockout animal”, in the jargon, have lots of uses in research. However, what they show us very clearly – just by looking at the picture – is that your kidney urine output, and water intake, adjust to match one another.

This is a slight over-simplification, since you take in water other ways than drinking (in what you eat, about 1000 ml /day), make some water via cellular respiration (about 300 ml / day) and lose water other ways than via the kidneys (in poo, about 100 ml / day, and via sweating and via evaporation from your mucous membranes and lungs, around 800 ml / day). But the basic principle is good – if you drink more, you will pee more. There are people with the same kind of problem as the Brattleboro rat (lack of urinary concentrating ability). They have a rare disease called (slightly confusingly) ”Diabetes_insipidus”, or more specifically “Central Diabetes Insipidus” if their problem arises from lack of vasopressin secretion from the (central) nervous system.

Er… what was all that stuff for?

The purpose of this lengthy preamble is twofold: first, to acquaint you with some basic principles of fluid balance and fluid and electrolyte physiology (including that good old rule: In = Out); and second, to make clear why what Heinz Valtin doesn’t know about body fluid balance isn’t worth knowing.

So what happened when Valtin went looking for the source of the “eight glasses of water a day” line, and for any evidence that it was based on any science, or that drinking this much was beneficial?

The answer is simple.

He couldn’t find any evidence. Not one bit.

The source of the 8×8 advice is a real mystery. The best guess Valtin has was that about 60 years ago, round about the end of WWII, a US Govt report said something like “the total amount of all fluids you need to drink a day is about the equivalent of eight glasses of water” – although this was not based on any particular scientific study.

Over time, and with the aid of the Water-Nuts and of literally billions of pounds/dollars in marketing spend, this has been transformed into “Eight glasses of water – you must drink this! – and other liquids don’t count!”

The other “Hydrationista Myths”

In his review Valtin also nails many of the other silly, but widely repeated, lines the Hydrationistas employ:

“Caffeinated drinks don’t count as part of your fluid intake, because they dehydrate you”

Not true. Of course they count – they are mostly water, so they are fluid. The slight diuretic effect of the caffeine in the drink does not “offset” all the water that is in it. We will come back to this one in a minute.

Note that I’m not talking here about small drinks with loads of caffeine, like a triple Expresso or a can of Red Bull. I’m talking about the kind of coffee, or soft drink, that most people drink. My standard cup of coffee is about 275 ml, which would take a fair bit of peeing out.

“If your urine looks dark, you are dehydrated”

Not true. It would be more accurately to say that “pale yellow” or “almost clear” wee (which the Hydrationistas tell you you should look for) means you have water –loaded yourself (i.e. you have drunk loads extra) and thus are peeing out unusually extra dilute stuff.

“When you start to feel thirsty, that means you are already dehydrated”

Not true. Your body detects tiny changes in “body water” very well. To put it more precisely, the body detects how concentrated your body fluids are, that is, their “osmolarity”, and a change of 2% is detected easily. The body then tells you to correct this small change by drinking more and peeing less out. The wonders of evolution. Anyway, the system is both incredibly sensitive, and fast. So you get thirsty because it is time for you to have a drink, but NOT because you are dehydrated.

[Dehydrated is what you will get if you start feeling thirsty and then drink nothing for the next several hrs. Dehydration is usually taken to mean that your body osmolarity has risen by 5% or more. So you get thirsty, and drink, without ever being close to being dehydrated.]

– and finally, one Valtin doesn’t discuss in precisely this form, but which has recently turned up in the literature for “Brain Gym” (comprehensively trashed by Ben Goldacre here).

“Liquids (other than water) are processed in the body as food, and do not serve the body’s water needs.”

Again not true, and total scientific nonsense. Common sense should tell you that a bit of dissolved sugar does not stop water being water. So the other fluids count. And so does water in what you eat, roughly a litre a day of it, see below.

Being charitable, this statement COULD have its origins in the fact that there is a bit of evidence, which Valtin discusses, that taking more fluids along with your meals might promote satiety (feeling full). Therefore one could hypothesize that consuming foods with high water content might make you feel fuller (all else being equal, which it rarely would be, so that all other satiety cues were the same).

Anyway, this might mean that it is a good idea to drink something with your meal (which most people do anyway, of course) since it could help moderate how much you eat.

I can just about see how, if you were a bit confused, you might interpret this as “that water in what you ate was processed as food” and hence didn’t count as water. You would be totally wrong, though. Of course, your confusion suits the Hydrationistas perfectly.

 

Back to your Daily FLUID (not water) intake

Your total water requirement is “filled” by the fluids you take in over the courses of a day. Some of that water is in your food, depending in amount on what food you eat – a general value that appears widely in physiology textbooks, as we already noted, is that you get about a litre of water this way. It depends on exactly what food – it wouldn’t take a genius to work out that grapes, or watermelon, or soft fruit generally, is mostly water. But all food contains water. The milk you put on your cereal (if you do) contains water. And so on, and so on.

If humans needed clear fluid above and beyond “other water intake”, then breast-fed new-born babies would all be dying of dehydration.

By now it should be abundantly clear that, if you take a quantitative look, a large part of the daily “drinking requirement” will be met by drinks OTHER than water. Hence all those family stories about “Grandpa Albert never drank water, only tea”. Valtin gives an example of a day’s intake from himself:

Representative daily fluid intake of H Valtin recorded on 29^th Aug 01

Breakfast coffee with milk 650

Orange juice 175

Lunch cranberry juice 240

Dinner cocktail 125

Water 250

Total fluid intake 1,440 ml

And here, for comparison, is mine, from last Sunday:

Representative daily fluid intake by the author recorded on Feb 17th 08

Breakfast Coffee with milk 550

Lunch Diluted apple juice 325

Coffee 275

Dinner White wine 300

Water 350

Total fluid intake 1,800 ml

These amounts match well to the widely-recognised daily fluid requirement of a standard human, that being typically summarized in physiology textbooks as “the 70 kg man”. Valtin summarizes various measurements of daily fluid intake, all of which tell you about the same thing – your daily drinking requirement, assuming you eat an average sort of diet, is probably 1.2-1.7 litres, give or take. Inter-person variability will mean a range of values.

Another thing you can measure easily is the amount you wee out in 24 hrs. This will be balanced, very approximately, by your intake. Again, Valtin summarizes the studies that suggest that average daily urine output is around 1.7 litres (1700 ml). The similarity of this to the fluid intake is clear.

The above is slightly simplified since, remember, there are there are other ways you gain and lose water. But the clear take-home message is that your body’s fluid balance system turns over nice and happily if you drink about 1.5 litres (1500 ml) or liquids (all of them), and wee out something slightly more. And if the mean fluid intake value is about 1500 ml, then anything between 1200 and 1800 might be right for you. Humans, after all, are not all the same.

But to feel you have to sluice down nearly two litres of water, as well as whatever else you drink a day – give me a break.

But we KNOW all that extra glugging is good for us! You can’t prove it isn’t!

Of course, some of the Hydrationistas insist they have an answer to this. They cannot really dispute the scientific body of evidence, as so masterfully summarised by Valtin. Instead, they simply claim it is all irrelevant, as there is no trial to show that drinking loads of extra water ISN’T good for you.

Dr John Briffa exemplifies this approach. A couple of months ago he discussed this issue on his blog, prompted by an article in the Christmas 2007 issue of the British Medical Journal that debunked several “health myths” including “drink eight glasses of water a day”.

“Absence of evidence”, intoned Dr B in one of his favourite lines, “is not evidence of absence”.

And other Hydrationistas take similar lines. That standard intake (around 2-2.5 litres by all routes, including food, or 1.5 litres of fluid) is simply that needed to avoid dehydration, they say. But it is healthier to drink lots more.

Note that they give no evidence for why this should be true – because there isn’t any. As Valtin clearly sets out, if you are a normal human individual, and you take more water in, your homeostatic system will rapidly adjust and pee more out. That is what your body has evolved to do. The extra flushing will mean more trips to the toilet, and considerable wallet-lightening if you are a bottled water enthusiast. But it won’t make you healthier.

 

 

And… absence of what kind of evidence?

Ah, say Dr Briffa and the other Hydrationistas, how do you know that? There is no rigorous clinical trial that says so!

Now this is an interesting general point, because it relates to a wider question about “Alt Health modalities”.

Is it really necessary to run complex, and expensive, large modern trials to demonstrate something is useless, when there is 50+ years worth of scientific and medical evidence, extensively tested, re-tested, critiqued and reviewed, showing that the theories on which the idea is based have zero validity?

In the water context, there is not a scintilla of scientific or medical evidence giving any grounds for the idea that super-slurping water will make you “better than well”

On the contrary, to repeat it for the umpteenth time in this piece, there is shed-loads of evidence that around 1.5 litres a day of LIQUID, plus what is in your food, is what your body has evolved to be happy with. And furthermore, that your body will “adjust” your thirst to get you to drink just that.

In statistical terms, what we would say is that the “prior probability” of the Hydrationistas’ view – “drinking lots of extra water, over and above what your body actually requires, is good for you” – being true is extremely low.

So under these circumstances, why spend millions (and it would be millions) running a trial to try and show that extra water drinking has health benefits?

Or put another way, on whom should any “burden of proof” lie for the idea that drinking an extra litre of water a day is “healthy”?

On the scientific and medical mainstream?

I don’t think so. The burden of proof clearly lies with the Hydrationistas. It is not the job of mainstream medicine and science to have to keep proving what is already brain-achingly obvious, and supported by all the science, simply because the Alt-ies find it convenient to say “No fair! No evidence!”

And it’s not as if there’s no money in water for anyone who could prove super-slurping made you “better than well”. Bottled water is a global mega-industry, with a market worth something close to a staggering Two Billion pounds a year in the UK alone. Plenty of potential funding there for some enterprising Hydrationista to run a proper study to demonstrate the benefits of super-consumption of bottled water.

Indeed, when he wrote his review five years ago, Heinz Valtin said exactly this.

“In view of the strong suggestive evidence cited [that people don’t need 8 glasses of water a day]… I would argue further that… the burden of proof that everyone needs 8 × 8 should fall on those who persist in advocating the high fluid intake without… any scientific support.”

 

And a bit later:

 

“Having found no evidence in support of 8 × 8 has placed me in the awkward position of having to prove a negative. I hope, therefore, that anyone who knows of contrary scientific evidence will bring it to my attention.”

 

Five years later, Valtin, and the rest of us, are still waiting. From which you can draw your own conclusions.

 

 

Drinking water – or bathing in it – can be deadly (not) – part 2 The men in grey suits… are actually on the case

Drinking water – or bathing in it – can be deadly (not)