The Evils of Soy


We intially broke the "soy conspiracy" story back in issue #87 in an article titled Bad Protein. However, since it's such a potentially important story, and since new evidence has since surfaced, we figured it was a topic worth revisiting. Hence this article.


A little over a year ago, soy protein was the talk of the town. It was invited to all the parties, and it was even rumored to be having a little romantic fling with Jennifer Aniston from Friends (before she married Brad Pitt).

Likewise, the general media was touting it to be the best thing since sliced bread, or was that 100% stone ground wheat bread? Oh well. Anyhow, since the government gave soy a "thumbs up" to the public, stating that, "25 grams of soy protein per day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease," people began to think that it was indeed the best protein around. After all, it was relatively high in quality, cheap, and healthy! What else could you want?

And to boot, a few studies arose from the muck to indicate that this protein may enhance anabolic hormone levels and may increase thyroid hormone levels while dieting. Sounds soooo good. Right? Well, after a good amount of both scientific and "real world" evidence has surfaced, it turns out that soy may not be so good after all. Especially for the male bodybuilder.

Sounds all too familiar to me. Reminds me of the evil-painted women that I and other hapless men have encountered in the past. Sure, she's beautiful, classy, smart, loaded, and best of all, horny! Nothing could be better in life. That is, until you start to discover that your wallet's missing 200 bucks and it now burns when you take a pee.

Ouch! Sounds pretty harsh, eh? Well, even so, this still isn't even close to what soy has done to us. I'll let you in on all of the evil and destructive things that soy can do to you, should you decide to consume it. Sadly though, we must be careful, as many companies are still adding this vile crud into protein formulas, bars, and meal replacements. Hopefully, after you hear what I have to say, you realize that soy shouldn't be consumed by male bodybuilders. Not even your worst enemy deserves the horrid effects that soy is capable of producing. Okay, enough rambling, let's get to it.

First though, before we begin, I just want to go over some quick review material, just to make sure we're all on the same page. The reason why soy is so bad basically boils down to the isoflavones that it contains. Two of these isoflavones, genistein and daidzein, are what cause the majority of negative effects seen with soy protein use.

These two villains bind readily to Estrogen Receptors. One such receptor is the Alpha receptor and the other, of course, is the Beta receptor. The Alpha receptor is the one generally associated with breast tumors, increased body fat, water retention, etc. The Beta receptor really isn't something to worry about. Anyhow, genistein and daidzein can bind rather well to the Alpha receptor.

No big deal right? Well, it might actually be somewhat beneficial if they didn't activate transcription to any significant degree, as this would be what's considered an anti-estrogenic action. In other words, it would be good if the compound binded to the site and didn't cause any growth, while preventing any naturally-produced estrogen from binding (the estrogen "parking spots" would already be filled). However, genistein does activate transcription to a significant degree after binding to the Alpha receptor and therefore will cause growth of tissues.(1,2,3)


Two of America's Most Wanted

Unfortunately, the two soy isoflavones that I mentioned previously can have numerous adverse effects on everything ranging from Testosterone production, thyroid production, muscle growth, and even health.

Let's consider soy's affects on T production first. The ability of soy protein to decrease Testosterone levels has been well demonstrated. One study displayed a 76% reduction of Testosterone production in men, after ingestion of soy protein over a brief period of time.(4) In yet another study, an inverse association was found between soy protein intake and Testosterone levels in Japanese men.(5)

Finally, in yet another study, using healthy adult males, a diet containing soy was compared to a diet that consisted of meat protein in terms of sex hormone concentrations. Well, after evaluation, Testosterone levels were significantly lower in the soy diet. Not only this, but the estimated amount of free Testosterone was 7% lower after the soy diet as well.(6)

Hey, mice didn't fare much better. Testosterone and LH were also lowered in mice consuming only the isoflavone genistein.(7)

The evidence seems pretty conclusive. There may, of course, be other factors, but it's enough to give one pause when considering whether or not he should add some soy to his next protein drink.


IGF, Thyroid, and the Girly Hormones

It's fairly clear that soy protein lowers testosterone levels. How does it affect estrogen and progesterone levels? You'd figure that genistein would at least reduce the activity of estrogen to some extent, since it binds at the same receptor site, right? Well, apparently not. It turns out that genistein does not inhibit the effects of estradiol and in fact has been demonstrated to exert an additive effect when combined with estradiol.(2,8)

This means that they don't interfere with one another and can both exert the same negative effects at the same time, thus, packing a double punch. Furthermore, genistein may potentially increase estradiol levels as well. It's thought that this may occur because genistein may deconjugate estrone in the gut and allow for it to reabsorb into the bloostream and convert to estradiol.(9)

It's possible that it may also exert some progestational activity.(10) Even worse is that the estrogenic activity of these phytoestrogens may have been underestimated in the past, as there is evidence that they may be much more potent in vivo as opposed to in vitro [test tube] studies.(11) Oh, and while we're still on the topic or hormones, soy protein has also been shown to decrease IGF-1 concentrations in male rats.(12) Oh, and I'd feel bad if I forgot to mention that it can lower T4 levels, too.(13)


Protecting Our Future

While planting a seed definitely isn't an immediate goal of mine, I'm sure there are plenty of guys out there who wish to pass on their superior genes. So, for these men, I urge you to not let your child or pregnant wife consume any products that contain soy. While there isn't concrete evidence as of yet, there's still enough to warrant some caution.

For instance, when female rats were fed genistein while pregnant, their pups weighed significantly less than the groups that weren't fed genistein.(14) Also, when young rats were given genistein, spermatogenesis decreased, as did body weight, testicle size, and possibly the urge to mate. Another study found similar results.(15,16)

Oh, and before I forget, genistein has been shown to cause testicular cells to die, in vitro at least.(17)


Healthy? I Think Not

The main reason why the government decided to "sponsor" soy protein was because it can supposedly reduce the risk of heart disease. However, the funny, or scary, thing is that soy has actually been shown to decrease HDL cholesterol.(18,19) HDL cholesterol is the good kind.

Furthermore, it's possible that the isoflavones can induce growth and malignancy of the prostate. This is because the ER Alpha is thought to be at least partially responsible for the induction of growth. So, in theory, since genistein can agonize the ER Alpha in much the same way as estradiol, then it could cause growth of the prostate.(20)


Okay, So What About my Muscles?

Okay, now let's move on to the important stuff. How good is soy protein in terms of increasing muscle growth? Well, when compared to casein, it was beaten in terms of both protein synthesis and breakdown.(21) So, we know that it can't match proteins like casein or whey. What else? Well, even though this might make you cringe, I feel obligated to tell you. Get this, genistein was shown to inhibit myoblast proliferation and fusion in a dose-dependent manner!

It decreased protein synthesis and inhibited protein accretion as a result. These results occurred even at the lowest dose. The authors concluded that if animals consume enough soy, those concentrations of genistein could potentially affect normal muscle growth and development.(22)

Now that's some frightening stuff! Okay, so things couldn't get any worse for soy, right? Well not only may it interfere with muscle growth, but it may screw with your pro-hormone usage. Why is that? Well, genistein may interfere with the conversion of 4-androstenediol to Testosterone, thus, reducing the effectiveness of your favorite supplement to a good degree! This happens because it interferes with the enzyme 3 Beta-HSD.(23)


The End?

Boy, I wish it were the end, but the fact is that many companies, with the encouragement of the government, will continue to add soy protein to their products. However, like many of us fringe-element weight lifters have for so many years, we'll stand by and endure while the rest of the world makes a big mistake.

The next thing you know, there will be a big story about how truly harmful this stuff is to the male. Hopefully it won't be too late. But hey, maybe I'm being a bit hypercritical here. I mean, who knows, this may actually be a good supplement for the average woman. They seem to think they need more estrogen and less muscle, so more power to 'em.

For those T-Vixens, however, stay away from it! Especially while pregnant. Anyhow, my advice for you would be to read every food and supplement label that you have to make sure that there isn't any soy within the product. I mean, hey, you'll be checking the macronutrient profile anyhow, so just skim on down to the ingredients from now on. Be careful, you'd be surprised by how many items have been tainted. For now, good luck and keep your eyes peeled.


References Cited

1.Breinholt V, et al. "Estrogenic activity of flavonoids in mice. The importance of estrogen receptor distribution, metabolism and bioavailability." Food Chem Toxicol 2000 Jul;38(7):555-64

2.Casanova M, et al. "Developmental effects of dietary phytoestrogens in Sprague-Dawley rats and interactions of genistein and daidzein with rat estrogen receptors alpha and beta in vitro." Toxicol Sci 1999 Oct;51(2):236-44

3.Stahl S, et al. "Phytoestrogens act as estrogen agonists in an estrogen-responsive pituitary cell line." Toxicol Appl Pharmacol 1998 Sep;152(1):41-8

4.Zhong, et al. "Effects of dietary supplement of soy protein isolate and low fat diet on prostate cancer." FASEB J 2000;14(4):a531.11

5.Nagata C, et al. "Inverse association of soy product intake with serum androgen and estrogen concentrations in Japanese men." Nutr Cancer 2000;36(1):14-8.

6.Habito RC, et al. "Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males." Br J Nutr 2000 Oct;84(4):557-63

7.Strauss L, et al. "Genistein exerts estrogen-like effects in male mouse reproductive tract." Mol Cell Endocrinol 1998 Sep 25;144(1-2):83-93

8.Santell RC, et al. "Dietary genistein exerts estrogenic effects upon the uterus, mammary gland and the hypothalamic/pituitary axis in rats." J Nutr 1997 Feb;127(2):263-9

9.Harrison RM, et al. "Effect of genistein on steroid hormone production in the pregnant rhesus monkey." Proc Soc Exp Biol Med 1999 Oct;222(1):78-84

10.Zand RS, et al. "Steroid hormone activity of flavonoids and related compounds." Breast Cancer Res Treat 2000 Jul;62(1):35-49

11.Nagel SC, et al. "The effective free fraction of estradiol and xenoestrogens in human serum measured by whole cell uptake assays: physiology of delivery modifies estrogenic activity." Proc Soc Exp Biol Med 1998 Mar;217(3):300-9

12.Aukema HM, Housini I. "Dietary soy protein effects on disease and IGF-1 in male and female Han:SPDR-cy rats." Kidney Int 2001 Jan;59(1):52-61

13.Klein M, et al. "Energy metabolism and thyroid hormone levels of growing rats in response to different dietary proteins–soy or casein." Arch Tierernahr 2000;53(2):99-125.

14.Flynn KM, et al. "Effects of genistein exposure on sexually dimorphic behaviors in rats." Toxicol Sci 2000 Jun;55(2):311-9

15.Atanassova N, et al. "Comparative effects of neonatal exposure of male rats to potent and weak (environmental) estrogens on spermatogenesis at puberty and the relationship to adult testis size and fertility: evidence for stimulatory effects of low estrogen levels." Endocrinology 2000 Oct;141(10):3898-907

16.Whitten PL, et al. "Phytoestrogen influences on the development of behavior and gonadotropin function." Proc Soc Exp Biol Med 1995 Jan;208(1):82-6

17.Kumi-Diaka J, et al. "Cytotoxic potential of the phytochemical genistein isoflavone (4',5',7-trihydroxyisoflavone) and certain environmental chemical compounds on testicular cells." Biol Cell 1999 Sep;91(7):515-23

18.Ashton E, Ball M. "Effects of soy as tofu vs meat on lipoprotein concentrations." Eur J Clin Nutr 2000 Jan;54(1):14-9

19.Madani S, et al. "Dietary protein level and origin (casein and highly purified soybean protein) affect hepatic storage, plasma lipid transport, and antioxidative defense status in the rat." Nutrition 2000 May;16(5):368-75.

20.Risbridger G, et al. "Evidence that epithelial and mesenchymal estrogen receptor-alpha mediates effects of estrogen on prostatic epithelium." Dev Biol 2001 Jan 15;229(2):432-442

21.Schadereit R, et al. "Whole body protein turnover of growing rats in response to different dietary proteins–soy protein or casein." Arch Tierernahr 1999;52(4):311-21

22.Ji S, et al. "Soybean isoflavones, genistein and genistin, inhibit rat myoblast proliferation, fusion and myotube protein synthesis." J Nutr 1999 Jul;129(7):1291-7

23.Keung WM. "Dietary estrogenic isoflavones are potent inhibitors of beta-hydroxysteroid dehydrogenase of P. testosteronii." Biochem Biophys Res Commun 1995 Oct 24;215(3):1137-44


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