johnwen I accept that the acid-tablet rapidly breaks down - its the journey down the stomach, and out the intestines in 5 minutes that is suspect, so I decided to write Dr. Hickey asking him about his reference. (Principles of Drug Action)
Hi Owen,
Briefly:
Cell membranes allow very small, non-polar, and lipid soluble molecules to pass.
The stomach is (or should be) strongly acid (HCl).
Weak organic acids are thus driven by the strong acid into the associated and relatively non-polar state (i.e. H+ A- becomes HA).
Thus small weak organic acids are often absorbed well in the stomach. In other words it is quite possible that vit C is absorbed in the stomach - and the extent depends on how polar is the 'associated molecule' etc..
Try this link to a section in a toxicology book which gives more detail:
https://books.google.co.uk/books?id=hWDNBQAAQBAJ&pg=PA619&lpg=PA619&dq=absorption+of+weak+organic+acids+stomach&source=bl&ots=Es-VCyEbGA&sig=0hNy7ft6Ywm0nTQSyucgBiZoEnM&hl=en&sa=X&ei=-SWUVbiYE4X8UqO7rjg&sqi=2&ved=0CDsQ6AEwAw#v=onepage&q=absorption%20of%20weak%20organic%20acids%20stomach&f=false
I hope the link works for you.
Steve
Unfortunately, the link does not work for me - johnwen?