Soy article [Archive] - John Stone Fitness Forums

JeremyLikness

Thu, February 24th, 2005, 07:06 PM

I love my edamame, too. Here is an interesting comparison of soy protein and whey protein:

Many people ask why [our company] uses soy as the major source of protein in its bars and drink mixes. A variety of factors have gone into this decision. The most important involves the fact that soy protein is complete and high quality; and that soy protein has been linked with many long-term health benefits…i.e. with reduced risk of several chronic diseases. In addition, soy protein has relatively low allergenicity and it is ecologically friendly (i.e. it’s production has a lower environmental impact than dairy-based proteins).

This does not mean that [our company] doesn’t appreciate the nutritional value of whey protein. We have used whey protein in [our company's] products in the past, and we may include it in products in the future. Whey protein is also high quality from a nutritional perspective. It may have some advantages for those whose primary goal is to build muscle. And it has some advantages in taste and mouthfeel, although newer, improved soy isolates are catching up in the sensory arena.

In general, though, our position is that a healthy diet is one that includes protein from a wide variety of sources, and that both soy and whey proteins can play a role as components of a healthy well-balanced diet.

But we often feel as though this position puts us in the minority. So much of what we see on the Internet and in certain fitness magazines is strongly pro-whey or strongly pro-soy, as if one of these protein sources were all good and the other all bad, in all situations, for all people. This is nonsense…pure Internet drivel…pure marketing hype. Yes there are people who are sensitive to, or allergic to soy. These people should avoid or limit their intakes of soy protein…just as people who are allergic to dairy proteins and should avoid whey. And yes, people who are vegan will want to avoid whey protein because it is animal-based. But these are not sufficient grounds to make the choice between whey and soy proteins on an all-or-nothing, black-and-white proposition for the vast majority of people.

The sticks and stones that get thrown back and forth between the soy and whey factions are “business as usual” within the food industry…all part of friendly competition. But on the home front, this industrial-grade bickering has left consumers confused, concerned, and generally hungry for objective information.

Several scales for assessing the nutritional value of protein have been developed over the years. These have been used to rate various proteins for their ability to support growth, supply important amino acids, and generally satisfy the human protein requirement. The first broadly accepted standard (developed in 1919) was the Protein Effectiveness Ratio (PER). This method focused on the growth supporting characteristics of a given protein, and it used rats (rather than humans) as the test animal. Because of the metabolic differences between rodents and humans, this method has been largely discredited and it is no longer used. A second method, the Biological Value (BV) scale, is based on the retention of protein nitrogen by the body. It is thought to be a measure of protein utilization. The BV scale stretches from 0 to 100, with a score of 100 indicating that virtually 100% of the protein nitrogen is retained by the body. Some people, particularly in the sports world, use this method, but it is not widely accepted within the community of nutritional scientists. Instead, the method that is now considered by most nutritionists (including many in the sports sector) to be the international standard for assessing protein quality is the Protein Digestibility Corrected Amino Acid Score (PDCAAS). This approach, developed by the Food and Agriculture Organization and endorsed by the US Food and Drug Administration, considers the amino acid balance of a given protein as it compares with the amino acid needs of humans (with specific reference to 2-5 year old children). It also takes into account the digestibility of the protein (how fully the protein is broken down and absorbed by the body). The PDCAAS scale stretches from 0.0 to 1.0, with a score of 1.0 indicating that the protein completely satisfies human needs from a quality perspective.

During the 1990’s, whey protein became the protein of choice among bodybuilders, due in large part to an intense and successful marketing campaign sponsored by the dairy industry. That marketing promotion was based on the fact that some whey protein isolates have a rating of 100 on the BV scale. In comparison, egg white protein (the traditional standard for bodybuilders) typically ranks in the 90’s, while fish, beef and soy proteins usually rank in the 70’s on the BV scale. (You will see a wide variety of BV scores for these foods because different people express the ratios in different ways, and because the techniques for measuring BV are imprecise and not easily replicated from one experiment to another.)

However, when the PDCAAS approach is employed (and again, this is the current international standard within the nutrition field), soy protein isolates, whey protein isolates, and egg white protein all score a complete 1.00, meaning that all exhibit very high, and essentially equivalent nutritional value in supporting human health.

The high PDCAAS score for soy protein isolates speaks to two important features. First, soy protein is well digested and absorbed by humans. (This is the “D” of PDCAAS). And second, soy protein is complete. It contains all of the essential amino acids in the proper balance required for human growth, development, and health. (This is the “AA” of PDCAAS.) Some authors will claim that soy is lacking in the essential amino acid methionine, as if to imply that soy contains no methionine. Not true. Soy is not rich in methionine but it contains enough of this amino acid to supply human needs under most circumstances. Furthermore, it is important to point out that the human methionine requirement can be partially met (reduced) by another sulfur-containing amino acid, cysteine. And when cysteine-plus-methionine content is considered, soy protein is nutritionally excellent.

Jeremy

I know soy, and Dr. Mercola, have been discussed on these forums. Both get mixed reviews. :D

I really have a hard time knowing what to believe when it comes to soy, but I just thought I'd post this in case in includes any "new" info:
http://www.mercola.com/article/soy/avoid_soy.htm

I still love my edamame...