I last blogged about the dangers of unfermented soy here. And, actually, I'd only use fermented soy very sparingly.
Here's another article on soy (Thanks, Uwe), and interview with Kaayla Daniel. The whole thing is worth a read (though I do wish they'd ditch the exclamation marks), but what comes out most prominently is the danger of feeding infants soy-based baby formula.
Soy lowers Testosterone levels! Just about all soy products on the market contain the phytoestrogens (plant estrogens) known as isoflavones. Plant estrogens have lowered Testosterone levels in rats, monkeys, and other animals as well as humans. For grown men, this usually leads to decreased libido and lower sperm count. There's an old wives tale that Japanese women punish their straying husbands by feeding them a lot of tofu!
We can joke about that but not about the effect on baby boys fed soy formula. Pediatricians are reporting more and more cases of emasculated boys reaching puberty with breasts and tiny penises. Undescended testicles are also far more common than they were in the past. […]
Infants on soy formula are extremely vulnerable. Remember that soy formula constitutes most if not all of their diets. Based on figures from the Swiss Federal Health Service, some of my colleagues have calculated that an infant on soy formula is getting the hormonal equivalent of the estrogen found in three to five birth control pills every day! […]
Studies on rats, sheep, monkeys and other animals suggest that the estrogens in soy infant formula can irreversibly harm the baby's later sexual development. And this is exactly what we're hearing from both parents and pediatricians.
Did you know that baby boys are supposed to experience a Testosterone surge during the first few months of life and in the large amounts you'd expect from a grown man? Most people don't, but all that Testosterone is needed to program the boy for puberty, the time when his sex organs should develop and he should grow facial and pubic hair and start speaking with a deep voice. If receptor sites intended for the hormone Testosterone are occupied by soy estrogens, however, appropriate development may be delayed or never take place.
For girls, soy formula has the opposite effect. It's likely to accelerate puberty and may cause reproductive difficulties later in life. The studies which supposedly prove that infants on soy formula develop normally consider only height, weight and other measurements of growth as measured in infancy and early childhood. Many of the negative effects don't become obvious until puberty.
Folks, if you eat processed foods, you're getting a lot of soy. Even those low-carbing without a Paleo approach to what you eat are getting lots of soy.