Soy May Be Riskier Than BPA

May 12, 2010
Ann Louise Gittleman, PhD, CNS

Ann Louise Gittleman, PhD, CNS

Award-winning nutritionist and New York Times bestselling author.

92098617Manufactured soy is linked to decreased fertility and possible thyroid problems.

Long-term consumption of soy protein may weaken fertility in males, a new animal study suggests. Compared to mice fed soy-free diets, those consuming soy protein had 25% lower sperm counts.

Consuming soy in the early years may decrease fertility in females. Researchers at the National Institute of Environmental Health Sciences recently linked genistein—a phytoestrogen in soy eaten from birth—with irregular menstrual cycles as well as ovulation and fertility problems in adult female mice.

Even “brief exposure to genistein can produce long-lasting effects in rats,” says biologist Heather Patisaul, PhD, at the NC State University. Why worry about toxic chemicals like bisphenol A (BPA) and not soy, she asks. “We see far more significant effects with soy than we do with bisphenol A.” A recent Korean study suggests that dietary exposure to soy phytoestrogens (like genistein) “poses a relatively higher health risk for humans” than do synthetic endocrine disrupters.

Dr. Ann Louise’s Take:

Finally researchers are getting onboard with my “unjoy of soy” bandwagon. I’ve been worried about the proliferation of soy “frankenfoods” for decades. First and foremost, soy is a relative newcomer to the human diet. Most soybeans grown in this country are genetically engineered—and these bioengineered foods have never been tested on humans.

While many people are highly sensitive or even allergic to dairy and grains (introduced about 10,000 years ago), soy foods are relative newcomers to the human diet—only about 200 to 300 years old—making them hard to assimilate even when they’re completely natural! In Asia, where soy is part of the traditional diet, it’s processed very differently, often fermented to make it easier to digest.

Swiss researchers at the University of Geneva Medical School even caution against feeding soy-based formula to infants, because of the potential long-term risk from phytoestrogens. Soy protein isolate—a manufactured form of soy—is the main ingredient in soy formula, which comprises one-third of the U.S. market, as well as soymilk and other soy foods.

Even after undergoing the high-temperature, high-pressure industrial processes used to make soy formula and milk, phytates and trypsin inhibitors remain, interfering with nutrient absorption. To make matters worse, some processing of soy produces lysinealine, a carcinogen that further reduces the already low cysteine content of soy.

A Mixed Message—at Best
Several recent studies even link soy consumption with breast cancer, although its phytoestrogens have been touted as a natural alternative to hormone replacement therapy in women. Premenopausal women do show lower estrogen levels when they take soy isoflavones, but pro-estrogenic effects have also been reported in breast tissue. In cell research, healthy breast cells from women who took soy isoflavones showed an increased proliferation rate, which may increase the risk for breast cancer.

While some years back manufacturers pushed for and obtained the right to publish a claim that soy foods may contribute to heart health, a year-long study of soy protein at Florida State University found no cardiovascular benefits in postmenopausal women who are at increased risk for heart problems. No wonder the FDA is reevaluating the soy protein claim.

Soy has also been linked to reduced thyroid function in a preliminary trial of its isoflavones among healthy Japanese. Infants with congenital hypothyroidism (sluggish thyroid) should definitely not be given soy—in formula or milk.

The Right Copper-Zinc Balance
The phytates in soy interfere with mineral absorption—particularly zinc, which is a critical component of 90 important enzymes in the body and the mineral antagonist to copper. Soy is an incomplete protein, notoriously deficient in the sulfur-bearing aminos (lysine and methionine). To add insult to injury, soy products are also very high in copper, further throwing off a healthy zinc/copper ratio.

Too much copper can suppress thyroid function as well as the liver’s ability to detoxify. That’s not all! Copper overload can lead to depression, fatigue, food cravings, frontal headaches, and weight gain.

Although I find zinc to be deficient in most Americans these days, vegetarians and vegans tend to be particularly low in zinc which makes it even more crucial for them to avoid most soy-based products.

That’s one of the reasons I created the soy-free, hypoallergenic Fat Flush Body Protein. It combines yellow pea and brown rice proteins – the latter providing the missing aminos in soy – to create one of the highest bioavailability protein powders on the market. And it satisfies for four hours! In combination with a copper-free multi (like the Female Multiple),  Fat Flush Body Protein will keep your body from giving out before your mind does, free you from those midday slumps, and give you the energy breakthrough you’ve been looking for!

Fat Flush for Life
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Ann Louise Gittleman, PhD, CNS, is an award-winning New York Times bestselling author of more than thirty books including The Fat Flush Plan series and her latest book, Radical Metabolism. She’s been rewriting the rules of nutrition for more than 40 years and is internationally recognized as a pioneer in the field of diet, detox and women’s health issues. 

For a FREE daily dose of tips and strategies for maintaining healthy weight, conquering insomnia, and much more…check out my Radical Health Tips.

I’d like to meet and greet you on my Facebook groups, so won’t you check us out at the Radical Metabolism RevolutionFat Flush Nation, or my Inner Circle!


  1. Gwen

    Unfortunately, the benefits of soy have been touted for too long by vegans and others claiming to know what is best for us and the environnment. Fortunately, I started hearing about the problems of soy about 12 years ago and have tried to keep it away from my family as much as possible. The problem is our whole food system is infiltrated with GMO soy, from animal feed to almost everything on our grocery shelves. Thank you Dr. Ann Louise for continuing to expose the truth about what I consider a fruad!

  2. Maria

    A few questions I’ve long had re: soy infant formula – if it contains enough phytoestrogens to alter the fertility of females what does it do to all the males being fed this from birth? Is there any further information regarding developmental effects on boys? If 1/3 of babies fed formula receive the soy base is this not a significant concern for the long term?? Could the copper/zinc imbalance, which may also result, be yet another contributor to childhood obesity including obese babies (yes there seem to be a lot of them out there)? Why is this product still sold and being promoted?? Your input would be appreciated! Thankyou.

  3. Administrator

    We agree!

  4. Mumsy Baker

    I like my fruit and cereal in the morning, and switched to soy when I couldn’t drink cows milk. What do I use for milk if not soy? What do you recommend for those of us who can’t or won’t drink cows milk, cheese, yogurt???

  5. Julie

    What about eating non GMO soy … like edamame? Does the same apply?

  6. Julie

    Mumsy, My husband is lactose intolerant too. He drinks Vanilla Almond milk. He actually prefers it over soy.

  7. Bonnie

    If you don’t like or cannot drink cow’s milk, try coconut milk… It is available either sweetened or unsweetened. It’s delicious! I find it in the organic section of my grocery store and it is packaged just like a half gallon of milk.

  8. Carol

    What to do when you’re allergic to dairy, grains, and tree nuts? It seems soy milk is the only kind of milk I can tolerate. But I limit my consumption to 1/2 cup each day in my coffee. Does this relatively small amount pose significant risk? I have noticed that my menstrual cycles seem to be longer than most women’s… could this be the source of the problem?

  9. Accidental Tourist

    My daughter is pregnant and planning on breastfeeding but in the event she cannot, is there an infant formula you can recommend? I breastfed my daughter but at about 1 year she refused the breast. I made my own formula from a recipe I found in Adele Davis book. Can’t remember if it was soy based but I eventually switched her over to goat’s milk. Cows milk made her break out with eczema.

  10. Lisa

    I have recently discovered Hemp Milk as an alternative, and I really like it.

  11. Carol

    What brand and flavor of hemp milk do you get? I tried one brand & didn’t like it at all… but I’ve heard they vary widely.

  12. Cathy Owens

    Mumsy—-I use green tea in my cereal, or sometimes watered down cranberry juice. Another favorite is almond milk, and I even found a good recipe to make my own. Seems most milk, at least cow and soy, is NOT good for us!

  13. administrator

    Best milk substitute is the Fat Flush Whey protein or Fat Flush Body Protein. Both are non-GMO and basically hypoallergenic. You can also dilute heavy cream half and half with water.

  14. Jeanette

    I use rice milk instead of soy or dairy. We like it in our house. I tried a soy based protein drink last year and my period lasted for at least 10 days. Soy seemed to effect my cycle. I stopped that in a hurry.

  15. Dee Schardt

    I like edame.Is this a dangerous soy product?


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