Manufactured 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!
Sources:
Fat Flush for Life
Why Am I Always So Tired?
https://www.ncbi.nlm.nih.gov/pubmed/20215976 https://www.ncbi.nlm.nih.gov/pubmed/20171261
https://www.ncbi.nlm.nih.gov/pubmed/20088450
https://www.ncbi.nlm.nih.gov/pubmed/19919579
https://www.ncbi.nlm.nih.gov/pubmed/19889829
https://www.ncbi.nlm.nih.gov/pubmed/20088450
https://www.ncbi.nlm.nih.gov/pubmed/20077194
www.prevention.com/cda/vendorarticle/soy/HN2910007/
