Archive for March 1st, 2008

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

March 1, 2008

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 AlkalinizerTM…!

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)