pH5 is 1000 times less acidic than pH2.
I think the person who wrote that article has got things a bit backwards in one respect. Stomach pH is lowest when fasted (maybe pH2) then rises quickly to maybe pH4-6 when we eat, and then drops back again quite quickly to about pH2. To have your stomach most of the time about pH5 is not normal. But whether humans still actually need such an acidic stomach is an interesting question. Our diet probably has a lot fewer dangerous bacteria etc. than when we first evolved. Here is two lots of research showing normal stomach pHs compared with people on PPIs, showing the effect of meals. The difference is about pH3 or 1000 times less acidic.
Websites disagree wildly - I just looked at about 8! Some say "becomes more acidic, to pH 6". Uuh???
Some say pH goes one way when you eat, some say the other.
I think I've found the problem. Took a while for the penny to drop.
The point we're/they're missing is the
amount of acid being produced is key not just "the pH".
(If you just say measure pH, it probably depends where, when, and if it's peak or average)
A little HCl is pH2, say. But so is
a lot of HCl. Trouble is, it then escapes to where it shouldn't.
At rest, not much is produced. When you eat, the pH shoots UP (less acid) because food/saliva is neutral-ish and as I said, overwhelming, but
then, so does the acid production. When the food's gone, the acid production should drop right off, to balance the saliva being swallowed.
In some folk it doesn't, so there's too much acid for too long and it escapes the stomach and they get ulcers etc.
[edit]I just found on medscape that it's a volume problem.
The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution.
"X times as acidic" isn't very useful. pH5 is 100 times more acidic than normal water at pH7.
Which isn't acidic 
Wassmore, Neutral pH in the stomach doesn't cause ulcers.
As reflected in the
oesophageal
pH (which apparently is used to diagnose excess stomach acidity ), the pH goes up , to resting levels, at night. To pH 6 or so in the oesophagus. Some people's pH there stays low, so they need medication, as they're producing acid for too long and develop ulcers and whatnot.
HCl is produced (more acidic) when you eat something - (vagus nerve >pepsin prodn stimulated).
From what I can find there is NO sensor of these acids in the digestive tract, so unlike blood pH (which has acid sensors) there's nothing to drive the para/sympathetic nervous system to specifically drive the normal feedback mechanism and turn
off acid production.
But I haven't found an authoritative complete description . Yet! I'll be back when I do.
THis fuzzy slide shows
op OK at night. (Below pH4 leads to acid reflux)
This shows what happens when there's too much acid/chyme, if the PPI dose is too low. I don't understand why the reflux doesn't show in the oesophagus.
Found a few snags if the acid reduction is too much:
Adverse effects
Adverse effects of proton pump inhibitors (PPIs) are usually mild and reversible.
- Adverse effects include headache, diarrhoea, nausea, vomiting, abdominal pain, constipation, and dizziness.
- Less common adverse effects include dry mouth, peripheral oedema, sleep disturbance, fatigue, paraesthesia, arthralgia, myalgia, pruritus, and rash.
- Rare or very rare adverse effects include:
- Subacute cutaneous lupus erythematosus (SCLE), which can occur weeks, months, or years after exposure to a PPI. If suspected discontinue the PPI and seek specialist advice if needed [MHRA, 2015].
- Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) have been reported very rarely, and rarely with omeprazole treatment.
- Taste disturbance, hepatitis, jaundice, depression, confusion, hallucinations, hyponatraemia, interstitial nephritis, leucopenia, leucocytosis, pancytopenia, thrombocytopenia, visual disturbances, sweating, photophobia, and alopecia.
- Long-term PPI treatment may be associated with uncommon, serious adverse effects such as:
- Hypomagnesaemia — symptoms include muscle twitching, tremors, vomiting, fatigue, and loss of appetite. Case reports after one year of PPI therapy, but may occur after 3 months. This usually improves after magnesium replacement therapy and discontinuation of the PPI [MHRA, 2012a]. Hypomagnesaemia may lead to hypocalcaemia and/or hypokalaemia.
- Increased risk of fractures — especially when used at high doses for over a year in the elderly [MHRA, 2012b].
- Clostridium difficile infection — due to the effect of decreasing gastric acidity.
- Rebound acid hypersecretion syndrome — may occur after stopping long-term PPI therapy, although this may be more a theoretical risk than clinical phenomenon.
[
NICE, 2019;
BNF, 2022;
ABPI Medicines Compendium, 2022]
