At 8:32 +1000 5/2/03, Phosphor wrote:

 >>OK, let's be accurate. The USDA database lists wild atlantic >salmon as:
 >0.981% SFA, 2.103% PUFA and 2.539 PUFA. >These figures plainly refute your
 >assertion.
 >can you send me the link for this?

The USDA figures for wild atlantic salmon can be viewed via:
http://makeashorterlink.com/?G36424853

The original URL is:
http://www.nal.usda.gov/fnic/cgi-bin/list_nut.pl?NDB_NO=15076&FDGP_CD=1500&MSRE_NO=100grams&FOOD_NAME=Finfish%2c%20salmon%2c

%20Atlantic%2c%20wild%2c%20raw



 >>>the quantities of DHA/EPA were definitely much more than in modern diet.
 >>>maybe 15-20 grams in coastal dwelling tribes.
 >>
 >>And what percentage of total fat intake would that be in your >opinion?
 >
 >on a 3,000 calorie diet that would be 10-15%.

OK! Some figures :)

For simplicity I'll work with the median values - 17.5 grams of PUFA
equates to 12.5% of caloric intake from fats.

So, total fat intake is 17.5/(12.5/100) or 140 grams.
140 grams of fat is 1260 kcal.
1260 kcal represents 42% of caloric intake from fats.

That leaves 1740 kcal from protein and carbs.
435 grams protein and carbs, 140 grams of fat.

Fair assessment?

Since you are a strong advocate of very low carb diets (1) I assume
that of the 435 grams of protein/carbs you would be happy for 400
of them (1600 kcal) to be from protein and 35 (140 kcal) from carbs.

That gives an overall nutrient profile of:
140 grams, 1260 kcal, 42% of calories from fats
400 grams, 1600 kcal, 53% of calories from protein
  35 grams,  140 kcal,  5% of calories from carbs.


 >what is the mechanism of protein toxicity?

My understanding is this:

When proteins are digested and burned for fuel, ammonia is a waste
product and this is present in the blood. One of the roles of the liver
is to metabolise this ammonia to urea which is then filtered and
disposed of by the kidneys.

The liver is only capable of metabolising a limited amount of ammonia
to urea. Once this ceiling is reached further protein in the diet
results in a build up of ammonia in the blood. Ammonia is toxic, i.e.
protein toxicity a.k.a. "rabbit starvation". The symptoms are nausea,
vomiting, fatigue and eventually death results.

The point at which the liver is unable to metabolise further ammonia
occurs when the body is obtaining approximately 30-40% of energy from
protein. Another source states that a 70 kg individual needs to obtain
more than 1000 kcal from protein per day to get into this state.

The diet above that I derived from your figures is well into the danger
zone for excess protein consumption.

If you want a more technical explanation and have the background in
physiology required to follow it, check this page out:
http://www.indstate.edu/thcme/mwking/nitrogen-metabolism.html

  ...R.



(1) References for this wild assertion:

At 7:55 +1000 29/9/02, Phosphor wrote:

 >i think we are all subjected to a rather ironic situation, namely that paleo
 >eating is very low to zero carbohydrates, but at the same time eating all
 >the carbs that actually happened to be available [ie hardly any], in order
 >to put on some survival fat.


At 14:29 +0300 3/3/01, Phosphor wrote:

 >i don't know the exact figure of fat in kangaroo, but taking your figure of
 >100 grams of kidney suet, that's a good amount for one day.  Add 600 grams
 >of meat and you could live on that indefinitely [from the point of veiw of
 >macronutrients anyway - add liver for extra vitamins].

That equates to 900 kcal from fat, 2400 kcal from protein. Ouch!