Essential amino acid requirements

Stuart Dunn dunns99 at erols.com
Fri Dec 17 10:09:54 EST 1999


pathos wrote:
> 
> In article <38592328.423B at erols.com>, Stuart Dunn <dunns99 at erols.com> wrote:
> 
> > pathos wrote:
> > >
> > > In article <3858BEBC.1EDD at erols.com>, Stuart Dunn <dunns99 at erols.com> wrote:
> > >
> > > > > 2) Calcium levels have nothing to do with pH of the urine.
> > >
> > > > They do effect the pH level of urine. The breakdown of protein produces
> > > > acids which are then excreted through the urine. Since the pH level of
> > > > urine must be maintained, the body excretes more calcium in the urine.
> > > > Cysteine and Methionine are the amino acids that increase calcium loss
> > > > when consumed to excess, and most people get lots of these two amino
> > > > acids from nonvegan foods. I did find some interesting information on
> > > > protein, and I'll post it sometime today.
> > >
> > >    1)Proteins are not broken down in the kidney.
> 
> > You think I didn't know that? I am not refering to protein digestion. I
> > was refering to the fact that amino acid breakdown produces urea and
> > other acids that are excreted through the urine.
> 
>  Stuart Dunn said:
> "Cysteine and Methionine are the amino acids that increase calcium loss
> when consumed to excess, and most people get lots of these two amino
> acids from nonvegan foods."
> 
> I assume when you say that Cys and Met increase calcium loss that the loss
> of both calcium and those two amino acids occured together through the
> kidney.  I reckon that I simply misunderstood you.
The chemicals that result from the metabolism of the Cysteine and
Methionine are excreted through the kidneys. The body does extract the
calories in the animal protein before excreting the chemicals that
result from its metabolism.
> 
> Another little sticking point is that Urea is not an acid.  If anything,
> it is more of a detergant-like substance.  Most excellent at denaturing
> proteins.  It does not alter pH in any way, Uric acid on the other hand
> does.
> 
> After doing some reading which I had little time for but was a good review
> of classes long gone, I found the following:
> 
> There are 21 amino acids and one pseudo amino acid.  Half of these are
> cosidered to be essential amino acids. They are Threonine,methionine,
> valine, leucine, isoleucine, phenylalanine, tyrosine, tryptophan, lysine
> and for infants, histadine.  They are cosidered "essential" because thier
> carbon skeletons can not be converted.  The corresponding alpha ketoacids
> can not be synthesized in humans.  So whether or not these amino acids
> come from plants or meat is of little consequence, BUT YOU MUST GET THEM.
That's right. All eight essential amino acids must be eaten.
> As for the daily intake of protein, the average adult has about 10 kg of
> protein in the body. 6 kg is in a metabolically active pool. Approximately
> 50 g of protein is broken down and released by the muscle.  If you are a
> big strapping body builder or a crazy rugby player or even a very active
> person then this number will increase.  But for lazy geeks such as myself,
> this number is pretty close.  Therefore, you only need to eat enough
> protein to make up for the loss, 50g/day or 0.8g/kg of person.  When
> accretion of body mass is occuring,ie growing children, pregnant women,
> peaple just off diets, active atheletes or very active peaple, then the
> requirement for protein may increase to 1.5-2.0 g/kg.
> 
> To all,
> This is my last post on this thread.  I feel certain that Stuart has no
> intention of learning basic biochemistry and physiology which is a shame
> because he does have the desire to know about it.  I hope others have
> enjoyed my ranting and to those that I have offended, I offer my humble
> apoligies.
> 
> Regards,
> Peter Pediaditakis
> University of Pittsburgh
> Department of Pathology




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