[Anny]

Hello, I was doing my science project for school on the questions "Does the PH level of the acid in our stomachs affect the digestion of proteins?". It turns out that the higer the acidity, the higher the absorbtion of the protein. Now, for a further questions, I was wondering if vitamins worked the same way as proteins, but in acidic levels?

My prediction would be the same, because when take in eveyday vitamins, proteins are also included in the pill, so the rate of dissolvation would be similiar.

If anyone has a website explaining this, please post! Thanks for reading  

[Albert]

The pills you normally take, containing proteins and vitamins as well as many drugs, are gastro-resistant capsules: they are soluble only when pH is above 6 (when it reaches 7, they've already gone). This protects your stomach and the content of the capsule.

The few medicines that don't present these 'envelops', generally speaking, are absorbed ONLY in the first part of the intestine: here the pH is low enough for keeping most of them undissociated (hence, easier to pass through a lipophilic barrier). Only extremely lipophilic substances can be accidentally absorbed by your stomach (it's called secondary absorption).

A general rule, although presenting many exceptions, says an acid  substance (drug, vitamin, protein, amino acid) is absorbed when its pka>pH. On the contrary, a basic drug when its pKa<pH.
I think that now it's clear enough how the pH affects absorption, isn't it?