Phil:
> > Chyme does not enter the kidneys, urine does.

Marilyn:
> Urine does not enter the kidneys - it is produced in and excreted from
> the
> kidneys....... Urea (which is what you mean) is taken from the blood,
> though: http://kidney.niddk.nih.gov/kudiseases/pubs/yoururinary/

Yeah, you're right, I meant to say urea or, even more accurately, the
components which make up urine. I don't think there's a one-word term for
those components, unfortunately.

> No I know that chyme does not enter the kidney - it goes from the
> stomach
> into the intestines. I am trying to follow the food trail so to
> speak....
> 
> I don't understand how food (or chyme which enters the blood through
> the
> intestines) which is a certain pH (it is regulated by the stomach first
> and
> then the pancreas [by using sodium bicarbonate]) can have a profound
> effect
> on the blood plasma pH.

Like I said before, I don't know all the details of the process. It would be
interesting to learn them.

> BUT you seem to say that the foods that make up the chyme, even though
> they
> may be of one pH value, will have another pH value *effect* on the
> blood
> plasma?

Well, I'm reporting that some respected scientists, peer-reviewed journals,
and others have said that certain foods have an acidifying effect on some of
the body's fluids. Some doctors and scientists have dismissed a dietary
connection, apparently because they are unaware of the research that has
been done on it. It's a relatively new field of inquiry so there is probably
much still to be discovered about it.

> How and when during the food trail, does that happen?

I don't know all the details. I think I understand what is puzzling you. How
does stuff from blood that the body keeps in a narrow pH range lead to urine
pH that varies pretty widely, even in a normal, healthy person? It's a good
question that I don't know the answer to. Someone better schooled in biology
might be able to tell you. We know that urine pH can be much lower than
plasma pH in a "normal" person, how the pH drops from plasma to urine I'm
not sure. 

Blood pH, range 7.35 - 7.45 
- "healthy" arterial blood pH = 7.41 
- "healthy" venous blood pH = 7.36

Urine pH range: 4.5-8.5; "healthy" range: 6.5-8.0

It's commonly known that cranberries acidify the urine and doctors will even
prescribe cranberry juice for patients who have urinary tract infections
(bacteria alkalize urine). That would seem to be a good thing to mention to
any doctor or academic who tells you that foods can't acidify the urine or
other bodily fluids. I probably should have mentioned that first, now that I
think about it.