Essential amino acid requirements

Siemel B. Naran sbnaran at uiuc.edu
Mon Dec 13 13:49:01 EST 1999


On Mon, 13 Dec 1999 10:33:23 -0600, River Mouse

>Without all eight of the essential amino acids present, your body CANNOT do
>anything with that protein except break it down to synthesize the
>nonessential proteins and treat any surplus like fat.

Well, the body may burn some muscle to make up for the difference (ie, for
whatever amino acids are lacking).  Then the protein you eat is fully usable.
But of course, we don't want this.


>Whey | Soy | Egg | Rice | EAA
>-----+-----|-----|------|----------
> 6.8 | 4.3 | 4.5 |  4.2 | L-Isoleucine
>10.9 | 7.2 | 6.8 |  8.6 | L-Leucine
> 9.5 | 5.5 | 5.5 |  3.5 | L-Lysine
> 2.5 | 1.2 | 2.7 |  2.4 | L-Methionine
> 3.1 | 4.6 |  ?  |  5.2 | L-Phenylalanine
> 8.3 | 3.3 | 3.6 |  3.6 | L-Threonine
> 2.0 | 1.1 | 0.9 |  1.3 | L-Tryptophan
> 6.4 | 4.4 | 5.1 |  4.7 | L-Valine

>If methionine is the limiting factor, you'll need over twice as much soy
>protein as you'd need whey protein to get the same usable EAA.
>
>Look at lysine, and you'll see that you need about three times as much rice
>as you'd need whey.

If you eat twice as much soy, you get twice as much of every amino acid.
Which means too much protein, and therefore lots of work on your kidneys
to get rid of the excess protein/nitrogen.



>Some foods are heavier in sources than others. Since I want to rely largely
>on soy sources for protein for the time being, I'm trying to find vegan
>foods which are balanced in favor of lysine, methionine, threonine and
>tryptophan to make up the difference. Peas and lentils are supposedly
>heavier in these, so the combination of peas and soy protein may result in
>something like whey's balance.

Grains are high in methionine, and maybe the others.  So wheat cereal and
soy milk is probably a good choice.  I use tofu in my spaghetti (because
it tastes good to me), and this might be balance too because tofu is soy
and sphaghetti is grain.



>Mind you - that's -whey's- balance. I'm still looking for a source of
>information on what ratios a body really needs. It may turn out that
>tryptophan or one of the others isn't needed in as great a proportion.

I think whole egg has the balance the body needs.  I looked hard on
the internet for a profile but couldn't find one (all I get are links
to products and info that I already know -- what the essential amino
acids are and what each one supposedly does).  Anyway, as whey protein
has a BV of over 100 on rats, I'd say it has the right ratios.

-- 
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siemel b naran
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