amino acid balance

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John Sankey - 11 Feb 2005 02:07 GMT

I'm looking at how to get enough and a proper balance of amino acids
from a diet. The following are the FAO/WHO/UNO Requirements
(mg/kgbodywt/day):

Isoleucine 10
Leucine 14
Lysine 12
Methionine + Cysteine 13
Phenylalanine + Tyrosine 14
Theronine 7
Tryptophan 3.5
Valine 10

But, when I put numbers on foods (from the USDA site), I get that a
typical 2000 calorie/day diet would supply some five times these
RDA's. Also, everyone says that vegetarians have the most problems
getting lysine, but using these RDA's it is methionine+cysteine that
is low on average for vegetables, not lysine.

Comments? Does anyone know of a site that discusses these RDA's in
detail with this sort of thing in mind?

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John Sankey - 11 Feb 2005 15:45 GMT

A few things I've found out:

1. the amino acid RDA's were set by studying nitrogen balance, not by
health studies;

2. the 'essential 8' amino acids form 39% of actual mamalian protein;

3. the RDA for total protein is 800 mg/kg/day;

4. the combined RDA for the 'essential 8' is 83.5 mg, only
10% of the total protein RDA.

So, the RDA measures are different for total protein and for amino
acids. Given that the average healthy food supplies 5x the RDA of the
'essential 8', and that the RDA's of essential8/totalprotein are 1/4
the composition of body protein, perhaps I should multiply all those
amino RDA's by 4 in order to get a more consistent dietary analysis.

Comments?

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John Sankey - 12 Feb 2005 16:27 GMT

"For a balanced amino acid food that very closely aproximates your
muscle tissue eat fowl eggs."

The USDA analyses give the following percent of RDA supplied by 100
calories of whole egg:

A B1 B2 B3 B5 B6 B8 B12 C D E K
10 4 25 0 20 7 8 0 0 6 7 0

LZ SF MU 6 3 CH FB
8 9 12 4 3 96 0

Ca Fe Mg P K Na Zn Cu Mn Se I
4 12 2 19 5 19 5 3 1 31 12

WHO RDA*4:
Tr Th Is Le Ly m+c p+t Va
9 18 15 16 16 11 18 16

So, yes the amino acids are reasonably in balance, but very little
else is, and the cholesterol is out to lunch.

Fowl eggs are the perfect food for young fowl, not for us.

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John Sankey - 12 Feb 2005 16:59 GMT

Alf Christophersen in Norway writes: "Over here we have 15% of energy
intake as protein as a thumb rule. Used in most countries outside US."

Wow! The US/Canada protein RDA is 43 g/day = 172 calories/day for an
adult, only 8.6% of the standard 2000 calories/day total diet. 15%
makes the WHO "RDA"s for amino acids even farther out of line.

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John Sankey - 12 Feb 2005 20:35 GMT

Update: I've found that the USA NAS is in press with their amino acid RDA's,
and they average over double the WHO ones:

Amino Acid WHO NAS
Isoleucine 10 19
Leucine 14 42
Lysine 12 38
Methionine + Cysteine 13 19
Phenylalanine + Tyrosine 14 33
Theronine 7 20
Tryptophan 3.5 5
Valine 10 24
total 83.5 200

See
http://books.nap.edu/books/0309085373/html/530.html

Still seems low compared to the total protein RDA, but better.
The quest continues ...

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John Sankey - 13 Feb 2005 13:38 GMT

"And a child has a higher protein need than an adult."

True, but I'm looking at major inconsistencies in RDA's even limited
to a healthy adult male of my weight, age and activity. Given the
draconian measures shortly to come into effect with the EU Codex,
this is of real concern.

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