Monday, 12 August 2013

Caffeine is Dehydrating Except for Coca Cola, Martians & the Similarly Minded

I recently watched two television programmes.  The first one, Britain’s Favourite Supermarket Foods (unfortunately, no longer available on the BBC iPlayer) was about food and included a bit about coffee and caffeine. The second one was about mental illness, called Failed by the NHS.  Based on the first programme, I decided to write this article to show that caffeine is dehydrating contrary to the claim in the show that this is a myth.  However, when I referred to my article about Caffeine Allergy to get started, I was reminded that many people may be succumbing to mental illness because of caffeine consumption.  Meanwhile, this wasn’t mentioned in the second programme and is rarely considered by the medical profession or others.  It just so happens that mental illness is aggravated by dehydration.  I may write another article about caffeine and mental health, but in this article I will focus on the dehydrating effects of caffeine with the use of chemistry and biology.
Net Loss of Water
In the foods programme, Dr Sarah Schenker, Dietician, said that caffeine is not dehydrating because it doesn’t produce a net loss of water.  But then she went on to say that this means that “you don’t pee out more than you’ve just taken in”.  Frankly, it is ridiculous to claim that caffeine is not dehydrating because of the amount of urine output because, of course, there are other ways to lose water besides urine.  For instance, I know that coffee used to make me sweat more.  Drinking a cup of coffee can raise the body temperature which is why it would cause one to perspire more.  Ever notice how on a hot day you may not pee as much but sweat more?  We also lose water in our breathing, and in our stool.  As a matter of fact, caffeine has a laxative effect on many people.  These issues were not considered in the foods programme.
Others argue that caffeine is not dehydrating with logic like this from Biomechanics Fitness and Performance:
Even if caffeine may increase urinary water loss in the short-term (within a few hours), physiological processes that oppose dehydration are more than capable of counteracting this effect when coffee is consumed in moderation.”
What does that mean?  It’s dehydrating, but it isn’t dehydrating?  Either it is or it isn’t.  And as I discussed above, caffeine doesn’t just increase urinary water loss.  I’m not singling out this reference for any particular reason.   I just happened across it and thought it was a good example of those who make unsubstantiated illogical claims.  One I would single out though is the Coca Cola Company, Beverage Institute for Health and Wellness interview with Dr Ann Grandjean.  She bases her hydration theory on scientific studies (on healthy young men) that looked at the effect of caffeine on urine output only and then said:
“So, although the science is clear, I'm afraid public confusion is likely to continue until this newer science is widely and repeatedly disseminated by educators in the classroom and the media through television, magazines and newspapers. And, of course, numerous Internet sites must be updated with the correct information.”
What she is really saying is that Coca Cola needs more propaganda and advertising to dispute the truth that caffeine is dehydrating in order to sell more of its caffeinated products.  If they say it enough, people will believe that caffeine is not dehydrating.  But, let’s now take a closer look at the physiological processes that are involved in hydration and dehydration and try to dispel any possible confusion.
Biomechanics Fitness and Performance also claims that “Coffee has not been shown to have any detrimental effect on electrolyte balance whatsoever.”  Electrolytes are electrically charged minerals that are in the blood, urine and other body fluids.  Sodium, calcium, potassium, chlorine, phosphate and magnesium are electrolytes.  When dehydration occurs, the balance of these electrolytes is upset because electrolytes are lost in water.  Coffee definitely has an effect on electrolytes, but is it a detrimental effect or a harmless one?
Perhaps the US Military has the answer.  They use a non-caffeinated product to combat dehydration which is advertised with this information:
“Even mild dehydration impacts health and performance; in extreme cases, dehydration is fatal.
·        Mental and physical fatigue and loss of alertness occur with as little as a 1% fluid loss. Reaction time slows with as little as 2-5% dehydration.
·        Muscle cramping, skeletal muscle fatigue, headaches, nausea and fainting occur with greater than 5% dehydration.
·                    Dehydration isn't just water loss. Significant amounts of sodium and potassium can be lost through sweating; losses are higher with diarrhea.  Replacing the water but not the electrolytes causes cramps, disorientation, and convulsions, as well as heart and nervous system problems, and can even be fatal (Funk D. Too much water can kill you. Air Force Times. Feb 2002).
·                    The body's primary water absorption mechanism requires the simultaneous presence of electrolytes and carbohydrates.”
Although I would not endorse this product which is like a medication with a patented rice syrup as the main ingredient, I think there is some validity in the company’s claims with reference to coffee consumption since coffee can cause sweating, diarrhea and increased urinary output (in the short term).

Sodium (Na+) ions are used against potassium (K+) ions to build up charges on cell membranes in muscle and nerve cells.  Na+ and K+ ions can pass through voltage gated ion channels in these cell membranes by facilitated diffusion, but they are also moved in and out of the cell by means of a transporter called the Na+/K+ ATPase in order to  accomplish 3 important functions:

1.  To establish the net charge as shown in the diagram.  “This resting potential prepares nerve and muscle cells for the propagation of action potentials leading to nerve impulses and muscle contraction.” 

2.  To maintain the osmotic balance of the cell.

3.  To provide energy to run indirect pumps.

Energy from the hydrolysis of Adenosine-5'-triphosphate (ATP) is used to actively transport 3 Na+ ions out of the cell and pump 2 K+ ions into the cell.  The pump is slow and operates constantly, but becomes progressively less efficient as the concentrations of sodium and potassium available for pumping are reduced.” 

Sodium and potassium ions are also important in the osmotic balance between the water in the cells and outside of them.  In a hypertonic environment where there is less fluid on the outside of the cell than inside (because of rapid fluid loss in urine and sweat, etc), the ionic balance will become upset, movement of Na+ and K+ ions will be hampered, and water will leave the cell by osmosis.  The cell will then shrink and crenate (take on a scalloped-edged shape).  However, there is evidence to show that the cell will regain its normal shape once hydration is re-established.  So there is a valid argument here for moderate caffeine imbibers in that the body will rebalance itself, if given the opportunity.

So far we can begin to see that there is more to dehydration than just water loss, but what is dehydration?
Dehydration is a net loss of water from the body.  When the loss of body fluids exceeds the amount that is taken in, dehydration is the result.  As mentioned above, all avenues of water intake and output need to be considered.
The American Pregnancy Association has no qualms in stating that caffeine is dehydrating.  Are pregnant woman so different from the rest of us?  Of course not.
Rather than just looking at the urinary output, let’s look at how caffeine disrupts kidney function by zooming in on the chemical reactions involved.  After all, caffeine is a chemical and the kidneys do more than eliminate waste as urine.  They are also responsible for other vital hydration functions such as the regulation of electrolytes, maintenance of acid–base balance, regulation of homeostasis, and generally serving as a filter for the blood.
Caffeine Disrupts Normal Kidney Function
Xanthine Alkaloid

Caffeine is a drug that is classified as a harmful hazard in the EU.  It’s a bitter, white crystalline water soluble xanthine alkaloid that acts as a stimulant which puts one in the “fight or flight” mode.  An alkaloid is a chemical compound with mostly nitrogen atoms.  By the action of the xanthine oxidase enzyme, xanthine is converted to uric acid.  Most uric acid is carried in the blood, passed through the kidneys and then makes its way out of the body in the urine.
Wiki states that caffeine is 100% excreted in the urine.  However, it also claims that caffeine is a methylxanthine which induces acid and pepsin secretions in the GI tract and that methylxanthines are metabolized by cytochrome P450 in the liver.  To say the least, this can all get a bit confusing.  No wonder companies like Coca Cola can drum up false propaganda about the issue.  But let’s please continue.
Xanthines increase glomerular filtration rate, that is, the flow rate of blood through the kidneys.  Xanthines also inhibit reabsorption of sodium ions (Na+) which results in a loss of reabsorption of water back into the blood from the tubules of the nephrons in the kidneys.  Normally, renal sodium reabsorption is very efficient with less than 0.4% remaining in the final urine, but caffeine interferes with this efficiency.  Caffeine is a natriuretic which means it increases the discharge of sodium through urine.

In other words, caffeine is a diuretic, a substance that inhibits fluid reabsorption in the kidneys, causing an increase in the fluid excreted.  The sodium that is unable to be reabsorbed is excreted in bodily fluids such as urine and sweat.  As a consequence, diuretics also reduce the extracellular fluid volume and the effective circulating blood volume.  This contributes to disrupting the ionic balance.  It is said that caffeine is a mild diuretic, but it’s still a diuretic.
Interestingly, a Kymos article claims that in Ethiopia it’s common to serve salted popcorn with coffee and that lots of coffee drinkers around the world add salt to their coffee.  Whether this helps with the sodium imbalance caused by coffee consumption is not discussed, but it shows some common sense knowledge about the sodium problem.

Xanthines, caffeine and uric acid are all types of purines as shown in the photo.  Purines are the most common nitrogen-containing heterocycle found in nature.”  They are water soluble, found in most body cells and are involved in several important cellular functions.  Purines are broken down into uric acid, and as previously mentioned, the kidneys are involved in regulating the amount of uric acid in the blood.  In a study considering multiple sclerosis (MS), it was suggested that uric acid and purine compounds can be considered markers of metabolic energy imbalance.  A certain amount of purines in the blood act as antioxidants by protecting blood vessels, but over a certain threshold, they are indicative of disorder.  Because caffeine interferes with hydration and the ability of the kidneys to regulate uric acid in the blood, it looks like a spanner in the works to me.
This is a bit off the beaten track, but in 2011, NASA researchers reported that the purines detected in the meteorites they had studied were consistent with products of ammonium cyanide chemistry.  They found “a plausible mechanism for their synthesis in the asteroid parent bodies, and strongly supported an extraterrestrial origin.”  They concluded that xanthine, which was one of the purines that was found in the meteorites, could actually be the result of terrestrial contamination.  Is caffeine, therefore, chemically based on an extra-terrestrial contaminate?  It does act as a disruptor of natural body functions and create toxins in the body.
Looking at what we’ve just covered, we can see that caffeine causes the kidneys to work harder, faster, and become less efficient, potentially leading to toxin build up.  Kidneys overloaded with toxins would be more prone to infection and inflammation, which in turn would cause further damage.  Dehydration aggravates this situation because the kidneys use water to flush out toxins.  When the kidneys become depleted, stressed, infected or inflamed, they cannot process the by-products of stress fast enough.  They consequently store excess toxins in other organs, in the muscles, and on the skin.  This condition is called kidney overload, burnout, hypofunction, exhaustion or insufficiency.  There are many reasons why kidneys may get to this point which have nothing to do with caffeine consumption, but clearly, caffeine may aggravate any existing kidney conditions and contribute to deterioration in kidney function.
The chemical and biological result of ingesting caffeine is that it causes an electrolyte imbalance that leads to the body losing water right down to a cellular level.  It is true that the human body can regain and maintain homeostasis, but it may do this by borrowing, exchanging and storing elements from one part to another with less than optimal results.  Over time, caffeine ingestion may contribute to the development of mild disorders such wrinkles/dry skin and high blood pressure or more serious ones such as gout and MS.
Consuming caffeine is like asking the body to do a balancing act on a roller coaster ride.  Caffeine clearly causes stress on the kidneys that are vital in the regulation of hydration of the body.
Based on my research, I maintain my view that the overall effect of caffeine ingestion is dehydrating, even for regular consumers.  To optimise hydration,  and health that is dependent on it, caffeine is best avoided.  But, the bit about xanthine being a contaminate from outer space was a nice final selling point for me.

Final Comments
According to a recent study, caffeine might be handy for the people planning to go to Mars in 2023 as it is claimed that it will assist them in adjusting their biological clocks to the 24.6 hour Mars day.  At least they'll make good use of the water they urinate out on the way to Mars as recycled urine will be a source of drinking water on the long journey, and even once they arrive.

I'm finding more and more evidence to support this statement: “Mars may seem far away, but it’s driving innovation right here on Earth.”  It would appear that Mars (and Coca Cola) is driving innovation, and utter lies, like caffeine isn't dehydrating.

Diagram credit: Cell Membrane
Photo credit:  Purines