Soy Isolate vs. Whey Protein?

[Thursdayisgod]

A friend just gave me a jub of soy protein (it's isolate), what is the difference between that and whey protein?

I just read this article http://www.teenbodybuilding.com/todd12.htm on it and it claims there is really no major difference. I am not super into lifting like a lot of people here, I do it recreationally because it feels good, makes me better at sports, and makes me look good, so I don't think the marginal differences should matter to me personnally, but I'm still curious.

Thanks.

[in10city]

A friend just gave me a jub of soy protein (it's isolate), what is the difference between that and whey protein?

I just read this article http://www.teenbodybuilding.com/todd12.htm on it and it claims there is really no major difference. I am not super into lifting like a lot of people here, I do it recreationally because it feels good, makes me better at sports, and makes me look good, so I don't think the marginal differences should matter to me personnally, but I'm still curious.

Thanks.

Whey and soy are obviously sourced differently and have slightly different amino profiles, digestion rates, biological fractions, etc...

While the problems with soy and male hormones have been exaggerated and that consumption of soy proteins in moderate amounts may be OK, diets high in soy have been shown to have negative effects especially with higher amounts of isoflavones.

Something additional to consider ...

There is a reason we recommend soy products for post-menopausal (read: no estrogen or minimally reduced tallies as such). Phytochemicals called isoflavones (as someone mentioned) has been the source of a LOT of research, particular interest has settled on two specific ones - genistein (probably the worst one) and daidzen (but these shouldn't be your only concern). These are ESTROGEN AGONISTS (in other words, they DO in effect have estrogen properties) and as a result help reduce menopausal symptoms that reflect reduced estrogen levels.

The levels of isoflavones vary precipitously dependent upon both the quality of the soy food and so forth and it is probably not in your best interest to ingest a cummulative tally that exceeds certain proportions, which makes some soy foods COMPLETELY off limits for bodybuilders.

An example:

Soy Isolate: Genistein concentration - 1100 micrograms per gram of this protein // Total Isoflavone concentration - 2174 micrograms per gram of this protein

Soy Concentrate: Genistein concentration - 111 micrograms per gram of this protein // Total Isoflavone concentration - 195 micrograms per gram of this protein

So, you can see with these two alone, the concentration is completely different (it may also alert you to something like difference between whey isolate and concentrate manufacturers use to cut costs).

D_
__________________
Dana Houser, MD, MHSA, CISSN
MAN Sports, Inc. Consultant
Director of Pharmacovigilance, MAN Sports
Industry Author