Soy Protein and Soy Supplements – Dangerous Food for Men?

They's not a healthy as you think. At least for men. (photo from

Soy foods and good health have become inextricably linked, as soy food supplements can offer several positive benefits. Soy is high in antioxidants, which, as we all know,  is beneficial to healthy living. It has been linked to helping lower cholesterol levels due to its high levels of omega-3 fatty acids and thereby reducing the risk of heart diseases. It can also lower the risks of prostate cancer because of its high content of isoflavones. Soy is also considered helpful in lowering blood pressure and building bone strength.

Various studies show, though, that soy is far from being perfect. The isoflavones and other substances found in soy protein such as phyto-estrogen and daidzein might actually present certain health risks for men. Several studies  have shown that soy consumption in men can have unwanted (at least by men) effects:

They's not a healthy as you think. At least for men. (photo from
They’s not a healthy as you think. At least for men. (photo from

Decrease  in testosterone

In a 2003 study published in the European Journal of Clinical Nutrition, researchers found that men who consumed 120 mg of soy isofavones a day, either thru soy food supplements or soy protein, experienced reduced levels of testosterone; and ironically, increased estrogen in their blood. Jamie Price, a retired military service man from the US, was dumbfounded at the  physical and psychological effects  of his soy milk consumption. As a health choice, he switched to drinking soy milk consuming almost 3 quarts daily. Pretty  soon,  he found himslef complaining about swollen and painful breasts. It looked as if gum balls were implanted underneath each nipple. His chest resembled that of a girl’s in her pre-pubescent years. The slightest touch triggered throbs. His emotions began to change as well, often in ways that were hard to separate from normal grief. He would have mood swings and had become more sentimental to a point that he would break out and cry at a sad movie, which he doesn’t do before. When he began dating again, it was as if the sexual aspect had evaporated. “I enjoyed the company of women,” he says, “but it was just like they were my friends. Even if I had wanted to do anything physical, I couldn’t have.”

Penis in peril

In a Harvard study published in the journal Human Reproduction, researchers have found a strong association between men’s consumption of soy foods and decreased sperm counts. Ninety-nine men reported their intake of 15 different soy-based foods, then underwent semen analysis. Those in the highest category of daily soy intake averaged 32 percent fewer sperm per milliliter of ejaculate than those who went without the soy.

Two other recently published papers reveal that at least one soy component impairs erectile function in animals—and may do so in men as well.  Jamie has also observed that while his penis has not completely atrophied, he says that it does not look as “dashing”  and wasn’t as “performing” as before.

The studies, published in the Journal of Andrology and Urology respectively, looked at the effect of daidzein on the sexual function of male rats. Moderate doses of the phyto-estrogen administered either in youth or adulthood significantly affected the quality of their erections. Among other changes, the daidzein-exposed males produced less testosterone, had softer erections, and experienced biochemical changes to their penile tissues that left these tissues less elastic and less capable of complete blood engorgement.

Some doctors have started recommending that soy be avoided by patients with erectile dysfunction, and because erectile dysfunction increases with age, it is also suggested that men ages 40 and above limit their soy intake.

Today, Jamie Price’s estrogen level is back to low to normal range, but the physical changes to his penis, his loss of sexual desire, and his heightened emotions have persisted.

Though it’s too early to conclude that soy can endanger men’s virility, all these findings from various studies can be a start. The scientific world , though, acknowledges that more studies need to be conducted. At this point, it is safe to say that soy is beneficial to men’s health when taken in moderation. Soy experts generally recommend consuming two to four servings of soy daily to take advantage of its nutritional attributes. Studies show that an intake of between 50 and 150 mg per day of isoflavones from soyfoods or supplements doesn’t lower testosterone levels. Similar amounts of isoflavones do not affect estrogen levels in men.

Like with everything else, everything taken in excessive amounts, even of the good things, can do more harm than good. To be sure, consult your doctor before adding soy to your dietary regimen to make sure soy protein doesn’t negatively interact with any of your existing health conditions or medications.

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