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We’ve all heard the mantra of how ‘important’ it is to keep the body ‘alkaline’ but is this strictly scientific?  Actually no, not at all – it’s just another myth like margarine is better than butter, eggs will kill you, veganism and/or raw-foodism is heathy – these unscientific myths abound, but that’s what they are – myths.  The pH myth also goes by the name of “the alkaline diet” or similar, with the belief that the body has to be ‘alkaline’ in order to be healthy, stop cancer and stop the sky falling on your head.  In truth though, some parts of the body are supposed to be pretty acidic.  This may come as a shock to some but stay with me here!

The pH of a solution tells us how many hydrogen ions the solution contains.  The pH scale ranges from 0-14; acidic being below 7, and alkaline being above 7.  Therefore an alkaline solution will have a higher pH than an acidic one.  Battery acid has a pH of 1.0, and distilled water has the perfect’ pH of 7 (perfectly neutral), but bleach has a pH of 13.  That said, let’s look at some of the pH values of different parts of the body.

  • Your skin needs to be very acidic in order that mould doesn’t grow on it, and has an optimal pH of 5.5. Your sweat together with the sebum will form what’s known as an “acid mantle” for your protection, which will range from a pH of 4.0-5.5
  • Stomach acid needs to have a pH of from 1.5-3.5. Battery acid has a pH of 1.0 – which tells you our stomach acid is not far off, and has to be very strong in order to kill pathogens in the food and to provide the right environment for protein digestion.  Trying to make the stomach alkaline defies reason. Stomach acid unravels the proteins to get them ready for the enzyme pepsin to chop them up into chunks called peptones.  Without this acid environment, not only will the pepsin not work – but you open your body to a multitude of viruses, bacteria and disease.  This highly acidic environment is there to protect you.
  • The normal pH of blood is 7.35 in other words ever-so-slightly alkaline. The only time you will see this change very marginally and temporarily is if there is diarrhoea, a drop in lung function, endocrine function, kidney function and urinary tract infection. But the blood pH is extremely tightly regulated between 7.35 and 7.45 – it must not change.
  • Blood filtered by the kidney (urine) is usually acidified by the kidneys which add hydrogen ions to the filtrate to tightly control the pH of the blood. Urine can have a pH of anywhere from 6.0-7.4. Under extreme circumstances this range can go right down to a pH of 4.5 and right up to 8.0.  For example after a heavy protein meal the urine can become very alkaline because of all the acid that was secreted into the stomach so there was none left for the kidney to excrete. Urine is therefore a very unreliable measure of overall body pH, and it is not a measure of overall health either.  Urine should be acidic as a general rule in order to protect against urinary tract infections.
  • The vagina has a normal pH of 3.8-4.5 – being too alkaline in fact opens the door to all sorts of infections from candidiasis to bacterial vaginosis, trichomoniasis and other conditions. The acidity protects the vagina from pathogenic bacteria.
  • The pH in the small bowel ranges from 5.5-7.0 as the acidic contents of the stomach begin to become alkalinized because the enzymes here only work in an alkaline environment. The pH gradually rises to 6.5-7.5 towards the end of the ileum and then it becomes acidic again in the
  • When it comes to saliva, a normal range is a pH of 7.1-7.5, however it can also fluctuate from 4.5 to 6.5, depending on the state of the teeth, last meal, etc.
  • If you want your sinuses to be healthy, bear in mind that normal nasal mucosa has an acidic pH of between 5.5 up to 6.5.

So my question to those who wish to be “alkaline” is this: which part of the body are you trying to make alkaline?  And then the next thing you may want to ask yourself is whether you want to interfere with the body’s ability to protect you against viruses, pathogenic bacteria and the ability to properly digest food! Consider too that an alkaline body is open more to illness than a normal acidic body.  What people similarly don’t stop to ponder is that the fungus Candida albicans thrives in an alkaline environment.  There are various ‘alkaline’ diets around and the bottom line of the fad is that there is an ‘ash’ left after eating a particular food, be it acid or alkaline, and that being more alkaline is to be in a healthier state.  Unfortunately this is not even vaguely scientific and is a cause for great hilarity amongst those who understand human physiology.

Food cannot influence the pH of the blood, as the body tightly regulates the pH of the blood and extracellular fluid or we would die – it needs to remain fixed at 7.35-7.45.  While diet can influence a lot of things, it cannot influence the pH of your blood.  Don’t get acidosis mixed up in this strange theory either – this only happens in a state of chronic renal insufficiency, not dietary changes.

The kidneys are not the only marvellous creations that regulate the pH of the blood; the lungs also keep the blood alkaline by excreting carbon dioxide from the bicarbonate ions carried by the blood to the lungs from the cells of the body.  The blood itself can keep its own pH within the tight range necessary by acting as a buffer or cushion against acidic or alkaline onslaughts.  The proteins in the blood can absorb both acidic and alkaline ions depending on which ones are getting out of hand.

Osteoporosis also has nothing whatsoever to do with the body’s pH – let’s get that straight right now.  Proponents of the ‘alkaline diet’ support the theory that acid-forming diets (aka carnivorous diets) cause loss of bone minerals and osteoporosis. But just for argument’s sake, let’s say that our kidneys and lungs could not handle the acid load of a high-meat diet and bones were demineralized in order to neutralize the acid as the theory goes, we would expect to see evidence of this taking place in clinical trials. But this is not the case at all.  Clinical trials and observational studies do not support the acid-ash hypothesis of osteoporosis.

What is interesting though is that observational studies have discovered that a higher protein intake is correlated with better bone health as shown in multiple studies, even though higher protein intake is supposedly more acid-forming.  Animal protein in particular has been strongly associated with much better bone heath.  The flimsy ‘evidence’ to the contrary has been thoroughly debunked.  Neither physiology, observational studies, clinical trials nor observational data supports this alkaline theory.  What about the theory of an acidic body in cancer sufferers?  It is true that the body can become more acidic than usual due to the cancer, but the short answer here is – the cancer causes the acidic environment, not the other way around.

Even if we assume we could change our blood pH or pH of other tissues – what many people don’t know is that cancer does in fact grow in an alkaline environment as well.  As mentioned above tumours grow faster in an acidic environment, but the tumours themselves create this acidic environment.  Researchers reported in a 2016 review of the theoretical link between dietary acid load, alkaline water and cancer, that there is no credible or scientific research to support this theory.  Personally, I think what happens is that when a person decides to improve their diet with a view to combatting cancer, they assume it’s the ‘alkalising’ effect of certain foods which do the trick when in fact it is just cleaning up a poor diet and including more antioxidant rich cancer-fighting foods.  It’s the holistic approach of no junk food, good heathy whole food and a change in lifestyle which makes the difference.  The evidence is simply not there for a result from any attempts to alkalise the body.  While acidosis and alkalosis are very rare conditions, true alkalinity is more dangerous than acidity.  For those overly concerned about acidity – consider that being too alkaline (or trying to be, anyway) will cause extremely thin, brittle hair. Heck no.

What about alkaline water? Just another myth I’m afraid: the moment it hits the stomach it becomes acidified.  The skin, sinuses, vagina, urethra, colon are all entry points for pathogens from the environment and they have to be acidic to protect the body from invasion.  One strange premise of the ‘alkaline diet’ fad is that acidic foods like lemons and tomatoes make your blood alkaline because of the residue of an alkaline ‘ash’ that they form – now that’s very easy to debunk.  If your blood pH departs from the tightly regulated range of 7.35-7.45 pH you will end up in hospital.  Anything below 7, or above 7.7 is a recipe for a fast and painful death, such as ketoacidosis (not to be confused with ketosis) as seen as a complication in type 1 diabetics.  With a pH of 7 or less the diabetic becomes unconscious.  Our amazing bodies are created to regulate pH in all the places it needs to – so don’t sweat – just enjoy good, whole food and let your body do the rest.

 Reprinted with permission from Sally-Ann’s article in LOSE IT magazine.