On Wed, 26 Jul 2000 07:34:01 -0400, Todd Moody <[log in to unmask]>
wrote:

>In my view there are a number of independent lines of evidence
>suggesting that for human beings a protein intake of about 30-35%
>of calories is optimal.  First there are the anthropological data
>from the study of contemporary hunter-gatherers.  Second there is
>the fact, established by Wolfe et al., that higher (i.e., higher
>than the 12-15% that is typical in the developed world) protein
>intake results in improved blood lipids.  Third, the importance
>of arginine-derived nitric oxide seems to point to a need for
>rather large amounts of dietary arginine, and this requires a
>large amount of protein.

Here we are again in a protein amount discussion. :-)

First, I must say that the Eades article (
www.cast.uark.edu/local/icaes/conferences/wburg/posters/sboydeaton/eaton.htm
) inspired me and convinced me, that total protein consumption in paleo
times was higher than recommendations (RDA,DGE) and higher as what nitrogen
balance tests show as actual nitrogen excretion in the presence of enough
other food energy. RDA, beeing about double of the nitrogen loss
measurements, can be seen as a substance keeping  value (enabling also
growth). A reasonable healthy value, i think.

As a look at paleo food sources shows, nutrient which is hardest to get
is food *energy*. Because most foodstuff besides fruit
has *much* more  structure components (protein) as reserves (calories).
The exception are seeds (like nuts), which yield for one day kcal  "only"
about one day's RDA protein. (E.g. 380g walnuts = 55g protein and 2650
kcal). Everything else -less dense- has much more protein than energy, in
relation. Including paleo-time vegetables.

Therefore in paleo times due to shortage of energy some more protein must
have been used calorically. It doesn't seem as if this caused any adaption
so that protein burning was more healthy. It looks as if the human body just
can bear the additional stress (this may be an adaption).

Up to a limit. Somewhere between 50%/50% calories from protein and fat,
and rabbit starvation (maybe 80/20 with only 20% kcal from fat).

>A trained person adds much more than red cells.  He or she adds
>muscle, in significant amounts, and that muscle needs a
>continuous blood supply.

I don't know which increased blood volume you assume. I suppose not
the doubled (14 liters). However, the amino acid pool is in the blood,
it's capacity will be a funtion of the volume.
If you assume a body builder at 10.5 liters (50% more!) than the blood can
hold 55 + 50% = 83g. This determines the maximum capacity of one meal
if it was *empty*.

(quoting Dr.Walsh at: http://www.zonehome.com/met/metprotnit.htm
<<., there is no storage form of protein that is used simply as a fuel
source at catabolic times. Likewise, although many
components of the body contain nitrogen, there is no actual storage form for
nitrogen. When there is dietary intake of nitrogen in the form of
protein, that nitrogen will be used for the synthesis of nitrogen-containing
compounds in response to signals directing that synthesis. If
nitrogen is taken in excess, it is immediately eliminated. The body will
never build up an excess of one or several proteins simply to serve as
a "reserve" for nitrogen. >>

>Protein-requirement ..  We can survive on fairly low levels,
>but to me the evidence suggests that we flourish with higher
>levels.

Or maybe we flourish only, because most micro nutrients are associated with
the protein part of various food items. And *this* is what we need.

>  Philip Thrift's diet appears to be
>quite low in fat, and yet he has no symptoms.
Philip low in fat? I computed else, from his statements.
But only he himself is able to answer or can specify exactely which kind of
meats is is, he consumes/consumed. E.g. How lean? Chicken with skin?

>> But what is the fate of the amino acids in the body builder?
>This assumes perfect utilization of the amino acids.  Also, the
>body builder's increased need for protein will also be a result
>of increased maintenance needs for the tissue that is already
>there.

I reconsidered the case and found some possible reason of increased nitrogen
loss, by "increased maintenance" (whatever that means.. )

Degraded protein's amino acids are reused, but not 100% efficient.

Walsh:
<<Synthesis and degradation is constantly occurring. These processes are not
100 percent efficient, and, in consequence, there is always a net turnover
and hence a net loss of nitrogen. ..  Even when there is no intake there
will always be some nitrogen excreted. When intake is high then there will
be a balance between intake and excretion.
>>
Walsh mentiones 6g nitrogen (40g protein) as the normal minumum  rate of
protein loss (for his normal 70kg human). Which is lost all days.
And this is only a fraction of the total synthesis/degradation per day.

You assume "increased maintenance" from workouts. It's possible that muscle
cells need more "repair" because of more free radical damage
(more oxygen throuput).
There may be more cell deaths leading to decomposition of the whole
apparatus. As far as reusing amino acids is "not 100% efficient" a actual
increased demand of is then to be assumed. And could be measured as nitrogen
loss.
I think, The total amount should be related to the 40g loss which is
measured for the whole normal body functions.
I can hardly imagine that workout may double the turnover rate.

>Vegetarian body builders (or strength athletes of any sort) are
>rare, and the few who exist use protein powder supplements of one
>sort or another, even though (as you have often pointed out) it
>is not difficult to get RDA levels of protein from vegetables.

So claims Philipp, that he "needed" it.

Amadeus S.