Here's a great piece by Dr. Stephen Chaney on the topic of "Soy and Boys."
You've probably seen some of those web sites talking about the dangers of soy - or read newsletters based on the information in those web sites.
If you believed those websites you would think that soy protein products were some sort of evil plot to undermine the health of the American public.
In my past e-newsletters I've talked about some of the distortions and misinformation found in those sites, but today I'd like to address a new topic - the effect of soy on guys.
The anti-soy web sites claim that the weak estrogenic effect of soy isoflavones can cause feminization of boys and weaken men's sexual drive and reproductive ability (Evidently, someone forgot to tell the Chinese about that last one!).
Chemically speaking that is nonsense because testosterone is structurally very similar to estrogen. The soy isoflavones resemble natural testosterone just as much as they resemble natural estrogen - which is probably why some studies show that soy isoflavones slow the increase in PSA levels for men with prostate cancer.
The claims found in the anti-soy sites are primarily based on animal studies, but that is misleading because mice don't metabolize the soy isoflavones in the same way that humans do.
So let's ask what studies with humans actually show. Two recently published studies have looked at the effects of isoflavones and isoflavone-containing soy protein in men. Both were meta-analyses - which means that they analyzed multiple previously published double-blind, placebo-controlled clinical trials. This approach increases the statistical power of the conclusions by smoothing out some of the natural variation seen in individual studies.
The first study (Hamilton-Reeves et al, Fertil. Steril., June 11, E-pub ahead of print, 2009) combined the results of 15 clinical trials and showed that soy isoflavones and isoflavone-containing soy protein intake had no effect on:
-total and free testosterone
-sex hormone binding globulin (a protein that binds to, and stabilizes, testosterone in the bloodstream
-free androgen index (FAI) - an index of all of the hormones in the bloodstream that have masculinization effects (Yes, guys - it's not just testosterone that makes us who we are).
The second study (Messina, Fertil. Steril., 93: 2095-2104, 2010) combined the results of 9 clinical trials and showed that soy isoflavones and isoflavone-containing soy protein consumption had no effect on:
-total or free testosterone levels
-circulating estrogen levels (Yes, guys - we do make some estrogen)
-sperm or semen parameters (Some guys might argue that this is the bottom line).
So the definitive results are in and, once again the Emperors (the doctors writing the anti-soy web sites) have been shown to have no clothes.
To Your Health!
Dr. Stephen G Chaney
P.S. The Wilson family drinks soy shakes daily...all 5 of us! I can tell when we miss a day (it's rare) because we are all a little less stabilized, have a little less "zip," and the boys are a little more whiney! Thank God for Energizing Soy Protein... a biologically complete, super-bioavailable, clean protein source!
If you believed those websites you would think that soy protein products were some sort of evil plot to undermine the health of the American public.
In my past e-newsletters I've talked about some of the distortions and misinformation found in those sites, but today I'd like to address a new topic - the effect of soy on guys.
The anti-soy web sites claim that the weak estrogenic effect of soy isoflavones can cause feminization of boys and weaken men's sexual drive and reproductive ability (Evidently, someone forgot to tell the Chinese about that last one!).
Chemically speaking that is nonsense because testosterone is structurally very similar to estrogen. The soy isoflavones resemble natural testosterone just as much as they resemble natural estrogen - which is probably why some studies show that soy isoflavones slow the increase in PSA levels for men with prostate cancer.
The claims found in the anti-soy sites are primarily based on animal studies, but that is misleading because mice don't metabolize the soy isoflavones in the same way that humans do.
So let's ask what studies with humans actually show. Two recently published studies have looked at the effects of isoflavones and isoflavone-containing soy protein in men. Both were meta-analyses - which means that they analyzed multiple previously published double-blind, placebo-controlled clinical trials. This approach increases the statistical power of the conclusions by smoothing out some of the natural variation seen in individual studies.
The first study (Hamilton-Reeves et al, Fertil. Steril., June 11, E-pub ahead of print, 2009) combined the results of 15 clinical trials and showed that soy isoflavones and isoflavone-containing soy protein intake had no effect on:
-total and free testosterone
-sex hormone binding globulin (a protein that binds to, and stabilizes, testosterone in the bloodstream
-free androgen index (FAI) - an index of all of the hormones in the bloodstream that have masculinization effects (Yes, guys - it's not just testosterone that makes us who we are).
The second study (Messina, Fertil. Steril., 93: 2095-2104, 2010) combined the results of 9 clinical trials and showed that soy isoflavones and isoflavone-containing soy protein consumption had no effect on:
-total or free testosterone levels
-circulating estrogen levels (Yes, guys - we do make some estrogen)
-sperm or semen parameters (Some guys might argue that this is the bottom line).
So the definitive results are in and, once again the Emperors (the doctors writing the anti-soy web sites) have been shown to have no clothes.
To Your Health!
Dr. Stephen G Chaney
P.S. The Wilson family drinks soy shakes daily...all 5 of us! I can tell when we miss a day (it's rare) because we are all a little less stabilized, have a little less "zip," and the boys are a little more whiney! Thank God for Energizing Soy Protein... a biologically complete, super-bioavailable, clean protein source!
