By Dr. Mercola
Might soy impair your sex drive to the point of being an aid to celibacy?
Traditional wisdom says yes, and a fair amount of science backs it up.
Many studies have shown that soy's estrogenic isoflavones interfere with the production and usage of testosterone in your body.
There's also some evidence that soy can cause gynecomastia (male breast enlargement), and plenty of evidence for its reproductive toxicity.
The most recent piece of evidence is a case study of a 19-year-old man who become vegan, began consuming soy in large quantities, and soon after experienced loss of libido and erectile dysfunction.
Lab assessment revealed low levels of testosterone with increased levels of DHEA.
According to Dr. Kaayla Daniel in an article on the Weston A. Price Foundation website:
"During the year prior to this workup, the young man's diet had packed a whopping punch of soy isoflavones, averaging 360 mg per day, from soy milk, soy crisps, tofu, soy sauce, soy nuts and edamame.
This level of soy consumption is far above average, yet increasingly common these days as people quit meat and dairy products for soy substitutes...
After discontinuing his vegan diet and eliminating soy foods altogether, he noticed a gradual improvement in sexual function over the course of a year and his lab tests revealed gradual normalization of testosterone and DHEA levels."
Is the Soy Myth Harming Your Health?
You may have heard that the consumption of soy dates back thousands of years and has been cherished for its health promoting benefits ever since. If you believe this, you're not alone. The introduction of soy as a health food in the West has been one of the most successful myth-making campaigns in the food industry.
Unfortunately, it's only half-true at best, and dangerously misleading at worst.
Soy was first used as a food during the late Chou dynasty (1134-246 BC), after the Chinese learned to ferment soybeans to make foods like tempeh, natto and tamari. The key factoid here is that these foods are fermented, which alters the composition of the soybean and makes it suitable for consumption. Alas, this all-important fact has been conveniently swept under the rug, and many now claim unfermented soy has the same health benefits of fermented soy.
Nothing could be further from the truth...
Another common misconception is that Asians consume large amounts of soy foods.
But again, the facts have been twisted for profits. According to the Weston A. Price Foundation, the average consumption of soy foods in Japan and China is about 10 grams (2 teaspoons) per day, and it's used primarily as a condiment, NOT as a replacement for animal-based protein and dairy. And again, we're talking about fermented soy. Modern non-fermented soy products simply do NOT confer the same health benefits as traditionally fermented soy foods.
Non-Fermented Soy Foods Can Interfere with Sperm Production
At the end of this article, I'll summarize many of the health hazards associated with eating unfermented soy, but first, let's review its impact on your sexual health. Last year, a Chinese study published in the Asian Journal of Andrology found that genistein (a naturally-occurring isoflavone in soy beans) alter the male reproductive system by interfering with the production of enzymes involved in the process of producing sperm.
According to the authors:
"These observations imply that the ability of soy isoflavones to regulate androgen biosynthesis in Leydig cells is due in part to action on Leydig cell 3beta-HSD activity. Given the increasing intake of soy-based food products and their potential effect on blood androgen levels, these findings are greatly relevant to public health."
Non-Fermented Soy Implicated in Precocious Puberty
According to another study, young female hamsters fed the soy isoflavone genistein showed physical signs of sexual maturity and interest in mating much more quickly than female hamsters that matured naturally. For boys, soy isoflavones appear to have the opposite effect; delaying or retarding sexual development.
Part of the problem is that soy isoflavones mimic estrogen so effectively that they are able to bind to estrogen receptors.
In young girls, they can therefore "turn on" the physical and emotional characteristics of puberty. (Soy is not the only factor causing preconscious puberty however. Other environmental estrogens play a role too, such as BPA, pesticides, supermarket meats, tap water with estrogen from birth control pills, and more.) Precocious puberty is worrisome, as girls who go through puberty early in life are at increased risk of developing breast and uterine cancer, both of which are strongly influenced by estrogen.
The Added Dangers of Genetically Modified Soy
One of the worst facts about soy is that 90-95 percent of it is genetically modified (GM), and the results of animal studies on GM soy are troubling in more ways than one. While even organic soy can cause a host of serious health complications, GM soy makes things worse, and may even have a disastrous impact on future generations.
Genetically modified or GM seeds are designed to be "Roundup Ready."
It allows farmers to spray Monsanto's Roundup herbicide directly onto their fields without harming the crops. (Ordinarily, if you were to spray Roundup or any other glyphosate-based herbicide onto a plant, it would rapidly die.) Unfortunately, GM crops have become notorious for requiring more pesticides than conventional crops.
According to Jeffrey Smith with the Institute for Responsible Technology, by 2004 farmers used an estimated 86 percent more herbicides on GM soy fields compared to non-GM fields.
The active ingredient in Roundup is glyphosate, which, in addition to the soy itself, can also disrupt the delicate hormonal balance of the female reproductive cycle. Glyphosate is also suspected of causing genetic damage, birth defects, infertility, and cancer. Women who consume GM soy products are also at increased risk for developing retrograde menstruation (the menstrual cycle backs up into your body instead of outward), which can lead to endometriosis and, ultimately, infertility.
It's widely known that genetically modified (GM) Roundup Ready crops contain Roundup residues, and a 2009 study demonstrated just how toxic these residues may be to your health. Even when researchers tested formulations of Roundup that were highly diluted (up to 100,000 times or more) on human cells, the cells died within 24 hours!
So when it comes to GM soy—and more than 90 percent of all US-grown soy is GM—you have a triple whammy:
- The soy itself
- The genetic modification, and
- The increased pesticide load
Could GM Soy Sterilize Future Generations?
Pregnant women in particular need to beware of consuming GM soy as damage to your child may begin in the womb. Glyphosate is toxic to the placenta, which is responsible for delivering vital nutrients from you to your child, and eliminating waste products. If your placenta is damaged, it could result in miscarriage or serious birth defects.
So, if you are pregnant, stop consuming unfermented soy products immediately!
Furthermore, as described by Jeffrey Smith, author of the bestseller Seeds of Deception, and Genetic Roulette, there are growing concerns about the potential for GM soy to create sterility in future generations.
In one animal study, hamsters were fed GM soy for three generations to evaluate long-term effects. The second generation had a five-fold higher infant mortality rate than the controls, a slower growth rate, and reached their sexual maturity later than normal. By the third generation, nearly all the hamsters were unable to reproduce altogether; they had been effectively sterilized...
So, how is GM soy affecting human reproductive capability?
As of yet, we don't know if it can actually cause sterility because it will take decades before those effects become apparent in the human population. That's why animal studies are so important, as the lifespan of a rodent is much shorter than a human's—and if those results are any indication, the future for ardent soy lovers may be bleak indeed. Because, remember, more than 90 percent of ALL soy grown in the US is genetically modified, so while foods containing GM ingredients do not need to be labeled as such, you can be fairly certain that if you're eating soy, it's probably genetically modified, unless the soy is USDA 100% Certified Organic.
NEVER Feed Your Baby Soy Infant Formula!
It's important to understand that infants exclusively fed soy formula receive the estrogenic equivalent of at least four birth control pills per day, and can spell absolute disaster for their development.
Male infants undergo a testosterone surge during the first few months of life, when testosterone levels may be as high as those of an adult male. During this period, baby boys are programmed to express male characteristics after puberty, both in the development of their sexual organs and other masculinity traits. Animal studies indicate that phytoestrogens in soy are powerful endocrine disrupters, and when you feed your infant boy soy formula, his body is flooded with female hormones that inhibit testosterone.
In infant marmoset monkeys, those fed soy isoflavones experienced a 70 percent reduction in testosterone compared to milk-fed controls.
This abnormal hormonal state can disrupt the normal pattern of development, and in addition to "feminizing" his body can also lead to learning disabilities and attention deficit disorder.
Premature development of girls has also been linked to the use of soy formula and exposure to environmental estrogen-mimickers such as PCBs and DDE. Almost 15 percent of white girls and 50 percent of African-Americans girls now show signs of puberty, such as breast development and pubic hair, before the age of eight. Some girls are showing sexual development before the age of three.
Again, pregnant women need to be aware that consuming phytoestrogens even at moderate levels during pregnancy can have adverse affects on the developing fetus and the timing of puberty later in life.
The Many Health Dangers of Soy
As mentioned in the beginning, the health problems related to soy, whether organic or GM, are extensive. In her book The Whole Soy Story, Dr. Kaayla Daniel points out that thousands of studies have linked soy to malnutrition, digestive distress, immune-system breakdown, thyroid dysfunction, cognitive decline, reproductive disorders and infertility—even cancer and heart disease.
If you have symptoms of any of the following diseases or health concerns, I would strongly urge you to take a closer look at your diet and eliminate all unfermented soy:
Immune system impairment
Severe, potentially fatal food allergies
The following list highlights many of the problems related to unfermented soy:
- High levels of phytic acid in soy reduce assimilation of calcium, magnesium, copper, iron and zinc. Phytic acid in soy is not neutralized by ordinary preparation methods such as soaking, sprouting and long, slow cooking, but only with long fermentation. High-phytate diets have caused growth problems in children.
- Trypsin inhibitors in soy interfere with protein digestion and may cause pancreatic disorders. In test animals, soy containing trypsin inhibitors caused stunted growth.
- Soy phytoestrogens disrupt endocrine function and have the potential to cause infertility and to promote breast cancer in adult women.
- Soy phytoestrogens are potent antithyroid agents that cause hypothyroidism and may cause thyroid cancer. In infants, consumption of soy formula has been linked to autoimmune thyroid disease.
- Vitamin B12 analogs in soy are not absorbed and actually increase your requirement for B12.
- Soy foods increase your body's requirement for Vitamin D3.
- Fragile proteins are over-denatured during high temperature processing to make soy protein isolate and textured vegetable protein.
- Processing of soy protein results in the formation of toxic lysinoalanine and highly carcinogenic nitrosamines.
- Free glutamic acid or MSG, a potent neurotoxin, is formed during soy food processing and additional amounts are added to many soy foods to mask soy's unpleasant taste.
- Soy foods contain high levels of aluminum, which is toxic to your nervous system and kidneys.
What Soy Products are Good For You?
If you were to carefully review the thousands of studies published on soy, I believe you would reach the same conclusion as I have—which is, the health risks associated with unfermented soy products FAR outweigh any possible benefits.
However, there is ONE exception, and that's traditionally fermented organic soy products, which do have health benefits associated with them. This is because the fermentation process reduces the phytate and "anti-nutrient" levels of the soybean, making their beneficial properties available to your digestive system. Please note that tofu is NOT a fermented soy food and is therefore not on the list of recommended soy products.
The primary fermented soy foods I recommend are:
- Tempeh a fermented soybean cake with a firm texture and nutty, mushroom-like flavor.
- Miso, a fermented soybean paste with a salty, buttery texture (commonly used in miso soup).
- Natto, fermented soybeans with a sticky texture and strong, cheese-like flavor.
- Soy sauce, which is traditionally made by fermenting soybeans, salt and enzymes; beware however, as many varieties on the market today are made artificially using a chemical process.