The Impossible Burger is made from soy. The idea that soy is estrogenic and feminizing has been around for a long time. So has study after study definitively debunking this myth. Cody Haun, a muscle scientist (Twitter, Instagram), published another one in 2018.

Setup. Scientists gave athletes a protein supplement twice per day and had them train three times per week. The supplement was either a placebo (PLA), soy protein concentrate (SPC), or whey protein concentrate (WPC).

The soy supplement (SPC) indeed contained soy estrogens. The other supplements did not.

There was no change in fasting serum estradiol (an estrogen) in the placebo (PLA), soy (SPC), or whey (WPC) groups. There was no change in testosterone in the placebo or soy groups and an increase in testosterone in the WPC group.

No difference in androgen receptor content in the muscle.

There is no difference in androgen-responsive genes in the muscle in any of the groups.

There is no difference in estrogen-responsive genes in the fat tissue in any of the groups.

Some more support. John Berardi from T-Nation and Precision Nutrition agrees.

So do leading nutrition experts.

In other words? Evidence overwhelmingly indicates, despite persistent myths, that typical intakes of soy protein have no impact on hormonal function in men.

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