What do those charts mean?



The WaiSays page about protein contains charts that may be hard to understand.
This page tries to explain.



I understand the charts with the list of the requirements for humans at different life stages.

...but I don't understand the indexed charts, which show that meth./cyst. are always the scarest. To what number are you comparing them to? That part has always confused me, no matter how times I try and figure it out.


That part is solely to support the theory that you can calculate protein quality by relating methionine / cystine contents to total protein contents.
Those charts support the claim that on average, relative to amino acid requirements, of all amino acids methionine and cystine are most scarse. So that the availability of methionine and cystine in a specific food determines the protein quality of that specific food. 
Thus, that part supports my claim that you can compare protein quality of different foods by relating methionine / cystine contents to total protein contents. So that the listing of foods by protein quality is accurate.



But the indexed chart that shows where meth/cyst. is the most scare and is underlined, highlighted and bold....

Is that based on milligrams/kilogram lean bodywieght like the first chart?

You are referring to the amino acid requirements chart, right?
No, this time the original amounts have been indexed, and only reflect the mutual ratios. This so that we can compare the ratios of requirements with the ratios of supply.




Can you help me understand what exactly indexed amino acids requirements mean? is that like that an average?
For example,
I see that according to FAO / WHO 1985 requirements an adult needs 13 mg/kg lean bodywieght of both meth. and cyst.

But the chart that shows the weakest links in indexed amino acid requirements for humans, it says 100 (this is 100 mg/kg lean bodywieght, right?). Where did you get this as, adult requirements seem much lower than 100 according the official requirements?

When I compare the indexed foods amino acids chart, I see that even if meth/cyst. are the scarest, the human adult still gets more than enough because they only need 14 mg/kg lean bodywieght. Right????

Indexing a group of numbers means that the ratios within this group remain exactly the same, but the level of this group is adapted to the level of another group of numbers, so that we can clearly compare them.

For example:

If a man daily needs
800 mg leucine
400 mg methionine / cystine
250 mg tryptophan

and the food he eats averagely contains per 100 gram:
500 mg leucine
150 mg methionine / cystine
100 mg tryptophan


How can you quickly see what amino acid is relatively most scarsely available?
To do so, we must compare, and go back and forward.
But, if we index the numbers above, we see a more clear picture. For indexing, you need to make one of the number 'the standard', equalling 100. So, lets make methionine / cystine 'the standard', and calculate the others by equally reducing them (:4 for requirements and :150x100 for supply).



Do you mean 150 divided by 100, which is 1.5 and works for the ratio?

I mean :4 for requirements and :1.5 for supply to index the numbers
So: 150 for the original methionine :1.5 = 100 for the indexed methionine.


Indexed requirements:
200 leucine
100 methionine / cystine
  63 tryptophan

indexed supply
333 leucine
100 methionine / cystine
  67 tryptophan


Now the picture is clearer; relative to the the need, compared to methionine (100 / 100), there is much more leucine (333 / 200) available, and a little (67 / 63) more tryptophan.
This way you can easily skim through large amounts of numbers and detect the patterns.



So now I'm understanding the indexing part, but I'm not seeing how meth/cyst. are still the most scarest? cause their all the standard. So how do I figure this out?
I'm not seeing how this indexed chart of different foods relates to the charts above it, the ones that state official amino acid requirements for different age groups? 

Back to the indexed charts:
If you want to know the availability of lysine in foods in comparison to that of methionine / cystine, both related to our need for these amino acids, we only need to check the numbers for lysine in the largest chart. Then you see that this number is mostly way over 300, while the indexed requirements are all way under 250.
This leads to the conclusion that lysine, on the average, is abundantly available.
What is the standard doesn't matter, because the ratios remain the same.
What you can see in the charts, that it doesn't matter what amino acid you focus on; in comparison they are always (on the average) less scarsely available, so that, on the average, methionine / cystine are most scarse.


What I showed for lysine, also goes for the other amino acids inj the charts; their supply / requirements ratios are over 100/100, and thus they are less scarse.

For example:

For tryptophan, supply is generally over 60,
while requirements are always lower than 57.
(higher than 100/100)

For valine, supply is always over 200,
while requirements are almost always lower than 200. (higher than 100/100)

Ahhh, that makes so much more sense!





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