Marilyn Harris:
> In other words there is little change in the usage of sodium
> bicarbonate
> regardless from what you eat.
>
> I don't understand Cordain (or you?): "In other words, foods that are
> alkaline in the stomach can become acidic after digestion and vice-
> versa."
> The chyme is usually very acidic upon leaving the stomach. (pH 2)?
I meant after the chyme--when the urine gets to the kidneys. You are still
getting thrown off by the stomach--let's forget about the stomach for the
moment so we can understand the process in question. The area to focus on is
the kidneys. What Cordain wrote and I reported is that the acidifying foods
can bring the pH of the urine below 5 as it arrives at the kidneys. The
kidneys cannot handle urine with a pH below 5 very well, so calcium and
bicarbonates are used there to buffer the urine and bring it up to around 5
or so.
> So, I question that there may be another reason for the urine pH
> variation
> (and blood pH variation before kidney buffering). There are so many
> variables.
>
> However, if the pH of the digested food mass (chyme) does change then
> that
> would point to food (or poor stomach acid production) as reasons for
> differing pH values in the blood-kidneys-urine process.
Chyme does not enter the kidneys, urine does. So you want to know what the
pH of the urine is when it enters the kidneys, not the pH of the chyme. So
to understand the acidification and buffering process, one would focus more
on the kidneys and urine than the stomach and chyme.
Here are some more excerpts on this:
Acid-base balance
http://en.wikipedia.org/wiki/Kidney
"The kidneys regulate the pH, by eliminating H ions concentration called
augmentation mineral ion concentration, and water composition of the blood.
By exchanging hydronium ions and hydroxyl ions, the blood plasma is
maintained by the kidney at a neutral pH 7.4. Urine, on the other hand, is
acidic at pH 5 or alkaline at pH 8.
The pH is maintained through four main protein transporters: NHE3 (a
sodium-hydrogen exchanger), V-type H-ATPase (an isoform of the hydrogen
ATPase), NBC1 (a sodium-bicarbonate cotransporter) and AE1 (an anion
exchanger which exchanges chloride for bicarbonate). ..."
The Kidney
http://www.dls.ym.edu.tw/ol_biology2/ultranet/Kidney.html
"In maintaining the pH of the blood within its normal limits of 7.3-7.4, the
kidney can produce a urine with a pH as low as 4.5 or as high as 8.5."
Kidney Health
www.informedcenters.com/kidney_health.htm
"Normally freshly voided urine is acid. Therefore, the PH which is a measure
of acidity may range from 4.0-7.0. People who eat high protein diets produce
a more acid urine than those that consume mostly fruits and vegetables.
Increased urinary acidity (lower PH) may also be present in diabetes, fever,
pulmonary emphysema, diarrhea and dehydration. Alkaline PH (Higher PH) may
also be noted in chronic inflammation of the urinary bladder, acute or
chronic kidney failure, or for intoxication of salicylate ( such as aspirin)
or other drugs."
Acid-Alkaline Balance and Your Health
by Virginia Worthington, ScD
http://www.price-pottenger.org/Articles/Acid_alk_bal.html#Author_bio
"The kidney also responds to the pH of the blood. If the blood is too acid,
the kidney excretes extra hydrogens into the urine and retains extra sodium.
Phosphorus in the form of phosphate is required for this exchange. The body
obtains this phosphorus from bone if it is otherwise unavailable. When the
bloodstream is extremely acid, the kidney uses a different method and
excretes ammonium ions, which contain four hydrogens, into the urine. When
the body is too alkaline, the process is reversed, and hydrogen is
retained."
Acidosis
http://www.nlm.nih.gov/medlineplus/ency/article/001181.htm
"Acidosis is excessive acid in the body fluids.
Causes, incidence, and risk factors
The acid/base status of the body (pH) is regulated by the kidneys and the
lungs. Acidosis is caused by an accumulation of acid or a significant loss
of bicarbonate. The major categories of acidosis are respiratory acidosis
and metabolic acidosis."
Feature: Is Acid Eating Your Bone?
Susan E. Brown Ph.D. CNS, director of The Osteoporosis Education Project in
East Syracuse, New York
http://www.susanbrownphd.com/research_publications/mar_05.htm
While we all know that acid rain is damaging to fish, trees and the
environment in general, few of us realize that an imbalanced diet can lead
to a low grade, but important, "internal acidity". Known as " chronic,
low-grade metabolic acidosis" this internal acid condition reduces bone
mass, hastens aging muscle loss, and contributes to the development of a
wide range of diseases from kidney stones, and osteoporosis to periodontal
disease. This metabolic acidosis is caused by excess intake of metabolically
acid forming foods, such as protein and processed foods, and deficient
intake of base-forming foods such as vegetables, fruits, spices, nuts and
seeds. ...
From:
Acid-Alkaline Balance and Its Effect on Bone Health
Susan E. Brown, Ph.D., CCN, and Russell Jaffe, MD, Ph.D., CCN
International Journal of Integrative Medicine
Vol. 2, No. 6 - Nov/Dec 2000
http://www.susanbrownphd.com/research_publications/articles/bjaffe.PDF
"For 80 years, it has been repeatedly confirmed that bone responds to an
acid load by
dissolving its basic buffering mineral salts. For background, the average
adult skeleton
contains a large but finite amount of Ca2+ (50-65,000 mEq, 99% of total body
stores) and
Mg2+ (1,060-1,600 mEq, 50% to 80% of body stores). Bone minerals serve as a
sizeable
reservoir of buffer, usable in the control of plasma pH. Extensive research
has
documented the following8-18:
1. Urinary calcium excretion is associated with bone loss.
2. Urinary calcium loss in the face of an acid load strongly suggests
cellular potassium
and sodium deficits.
3. Bone loss is accelerated in the face of magnesium deficit.
4. Urinary calcium excretion parallels total acid excretion until
substantial calcium and
magnesium deficits accumulate.
5. Upon significant depletion of buffering mineral salts, compensation for
acid load is
reduced, intracellular and first-morning urine pH is concomitantly reduced,
and the
consequences of metabolic acidosis are accelerated. As an equilibrated
specimen,
first-morning urine pH is a useful clinical approximation of the cellular
and systemic
acid/alkaline state.
Less appreciated, however, are the following facts:
1. A variety of alkaline buffering salts (including those of sodium,
potassium, zinc, and
other minerals) are stored in bone. They are also lost from bone in the
obligatory
buffering of excessive metabolic acids.19
2. The contribution of contemporary dietary patterns to the induction of
excess metabolic
acids has been clinically underestimated. These fixed acids, which must be
neutralized
with alkaline buffering mineral salts, are largely the result of less
healthy dietary
choices.20,21
3. The mineral deficits in our soil and water reduce the availability of
minerals in the
conventional food supply.22,23
4. Compensated chronic metabolic acidosis is more the rule than the
exception. The
results are depletion of bone tissue and a disposition to chronic
illnesses.24-28
Thus, although osteoporosis is a complex and often multi-faceted disorder,
we propose
that primary osteoporosis is largely secondary to acquired and reversible
chronic
metabolic acidosis."
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