T Nation

NSCA Journal Article On Soy


I just was looking at The NSCA Strength and Conditioning Journal and there was a study on 3 groups: 1 group weight trained and consumed 3 soy protein bars, the next consumed whey protein bars, and the last consumed no protein bars. Each group lifted weights in the same format.

It was determined that the soy and whey protein groups increased lean muscle mass while the group who just lifted without any proteinbars did not increase mass.

Jose Antonio suggests that soy is equal in value in adding muscle mass. If this is true, is there a negative effect from soy as in estrogen production or is that really just a myth?


They actually needed a study to determine that a lifting group who ate protein would gain more muscle mass than a group who didn't eat protein?

Anyway, on a point of relevancy, Whey, in its various forms, is a quick-absorbing protein, great for post-workout. Soy, on the other hand, absorbs slowly and stays in the system longer, but carries the drawback of containing phytoestrogens, which in clinical studies have been shown to be as effective as true estrogen hormone replacement.

Even if the muscle building properties were the same in a short-term study, I would personally rather not take my chances on using a soy product that is quite likely an inferior muscle building protein, tastes worse, and is going to make my chest rival my girlfriends in terms of composition.


The study determined that the whey and soy protein users gained the same amount of muscle.


Correct, but I'm assuming it was a fairly short term study?

If so, the negative effects of the estrogen promotion by the soy protein would not have had a chance to occur, or at least to be noticeable, as it would in the long-run, which is exactly what a weight training athlete would encounter, a long-term effect. Unless the study was a truly comprehensive one done over a long period of time, which I am unsure of.

Either way, Whey has no negative side effects that I'm aware of, and plenty of positive ones, so I just don't really see a case for choosing Soy over it.


I came across this study a while back dealing with the effects of soy protein on hormone levels.


If you skip the medical jargon (like I did) and go right to the conclusion, it pretty much explains the results.

"In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone with minor effects on other hormones, providing evidence for some effects of soy protein on hormones. The relevance of the magnitude of these effects to future prostate cancer risk requires further investigation."

Your best bet is to simply leave soy alone and stick with Grow! and dead animals for your protein.


Mike Mahler, one of the popular strength coaches here at T-Nation and elsewhere(a new article is pinned up as we speak) is a vegeterian, not small at all, and uses pea protein powder and rice protein powder for his shakes.


Nice plug. Yes, I have read that Bill Pearl was a vegetarian. I am not will eat anything that moves. I am using whey right now but am always open to economical choices.


soy protien isolate is not a slow protein


What are the rates of soy isolate compared to whey hydrosolate, isolate, and concentrate? Milk protein?



After reading through the study it seems that soy will reduce DHT levels and increase levels of DHEA with no significant effect on free testosterone (by the end of the (56 day?) study).

The decreases in other hormones on day 29 were gone by the end of the study (levels returned to approximately pre-study levels) which makes me think that the subjects had adapted to the soy consumption with respect to these hormones. I don't know what the effect of lowered DHT and raised DHEA will have on muscle mass but it appears that there is a possibility that soy consumption will decrease prostate cancer risk.

In my book low risk of cancer is good, and from the first study mentioned it appears that soy may not be THAT bad in terms of muscle growth. So maybe soy is alright after all.


What about other dry beans such as black beans and pinto beans that have a high deal of protein (for beans)? These have an incomplete amino acid profile but do they have the estrogenic effects? Maybe the soy fear is part wives tale, I don't know. I just saw this 1 study and was curious.