4 replies to this topic

[Logan]

I've been told and have read that the only way to get a true complete protein that is recognized and fully utilized by muscle is through meat and dairy. I keep reading that soy is a complete protein, but I think my co-worker who is a nutritionist insists that it falls slightly short. Anyone have any hard facts on this subject?

[Skötkonung]

I've been told and have read that the only way to get a true complete protein that is recognized and fully utilized by muscle is through meat and dairy. I keep reading that soy is a complete protein, but I think my co-worker who is a nutritionist insists that it falls slightly short. Anyone have any hard facts on this subject?

In terms of amino acids, it is a complete protein. However, since soy protein are bound up by hard-to-digest cellulose, their true immediate availability may fall slightly short of most animal proteins (i.e. slower digesting).

PDCAAS is a reliable way of judging the relative quality of a protein.
http://en.wikipedia.org/wiki/PDCAAS

[rwac]

PDCAAS is a reliable way of judging the relative quality of a protein.
http://en.wikipedia.org/wiki/PDCAAS

I don't know about that. This paper claims that PDCAAS overestimates the protein quality of soy protein.

http://jn.nutrition..../5/758.abstract

The Protein Digestibility–Corrected Amino Acid Score Method Overestimates Quality of Proteins Containing Antinutritional Factors and of Poorly Digestible Proteins Supplemented with Limiting Amino Acids in Rats¹

• Ghulam Sarwar

Abstract
The validity of the protein digestibility-corrected amino acid score (PDCAAS) method in predicting the quality of fourteen protein products was compared with the commonly used protein quality methods, protein efficiency ratio (RER) and net protein ratio (NPR). A rat growth and balance study was conducted to determine protein digestibility and quality of the animal and vegetable protein products by the PER and NPR methods. Amino acid compositions of the products were also determined, and PDCAAS were calculated using a rat and a human pattern of amino acid requirements. Compared to the biological methods, the scoring method overestimated protein quality of mustard flour [PDCAAS of 84–92% vs. relative PER (RPER) or relative NPR (RNPR) of 0], raw black beans (PDCAAS of 45–72% vs. RPER or RNPR of 0), alkaline-treated lactalbumin and soybean protein isolate (PDCAAS of 44–67% vs. RPER or RNPR of 0) and heated skim milk (PDCAAS of 29–31% vs. RPER and RNPR of 0–5%). The scoring method also overestimated the protein quality of zein (true protein digestibility of 63%) supplemented with Lys, Met, Thr and Trp (PDCAAS of 63–71% vs. RPER and RNPR of 3–44%). These data demonstrate that the PDCAAS method is inappropriate for predicting protein quality of those protein sources which may contain naturally occurring growth-depressing factors or antinutritional factors formed during alkaline and/or heat processing.

[ajnast4r]

like skot said... soy is a complete protein on paper, but in the gi tract its a different story. rather than falling slightly short, its slightly over the 'line' of technically being a complete protein...

unfermented soy is high in various 'antinutrients'... phytate, trypsin inhibitors and such. the only soy i will eat on an even somewhat regular basis is sprouted tofu or various fermented soy products (tempeh being my fav)

you'll read a lot of 'things' about soy online... just keep in mind that the soy industry is a heavily financed political player and just like the other heavy hitters (dairy industry, meat industry) they have paid to shape how their products fit into modern dietetics.

Edited by ajnast4r, 10 January 2011 - 07:52 PM.

[yoyo]

Refined soy protein I think is ok. Though personally i use pea protein because it tastes better. I don't think fast protein is ideal unless all you want it muscle growth.