Let’s Talk About Soy – Is It Good or Bad for Health

For quite some time now, I have been against the consumption of soy, especially in the form of protein isolates and phytochemical isolates. My idea to put together this compendium (a veritable vade mecum) of evidence against soy came from an argument I had with a friend’s mom who, to this day, refuses to believe that soy is harmful.

The Evidence

I decided to start with the common screams pertaining to “save the children” that are often heard with regards to sports supplements (check the PH ban).

I quickly found that a recent study showed that soy-based infant formula might weaken babies’ immune systems. To give this report a little more credit, I included the fact that it was reported in several national newspapers, including the New York Times.

You know how people like things hyped by the media. There was also a study published in the March 1, 1997 issue of the American Journal of Epidemiology, which told the tale of a large number of asthma sufferers, numbers upwards of 200 people, who were seeking treatment to there ailment.

Further investigation showed the presence of cargo vessels carrying soy to be the probable cause of the people’s asthma problems. Was it a coincidence that the weather patterns and cargo history data linked up? Maybe. But similar outbreaks of epidemic asthma near a harbor in Barcelona, Spain, were also traced back to the release of soy dust when shipments arrived.

Soy and Immune Abnormalities

An article published in the Proceedings of the National Academy of Science (May 28, 2002) has raised concerns about soy. When researchers injected mice with the soy isoflavones genistein and daidzein, they found upon analyzing the thymus gland that the injections produced dose-responsive decreases in thymic weight of up to 80 percent.

The researchers are quoted saying, “Critically, dietary genistein at concentrations that produced serum genistein levels substantially less than those in soy-fed infants produced marked thymic atrophy. These results raise the possibility that serum genistein concentrations found in soy-fed infants may be capable of producing thymic and immune abnormalities, as suggested by previous reports of immune impairments in soy-fed human infants.”

Clinical Professor of Pediatrics at Georgetown University Medical College, Naomi Baumslag, an expert on breastfeeding, explains numerous reasons for parents to avoid soy infant formula:

Add to that the fact that soy products actually increase requirements for vitamin B12 and vitamin D, and you’ve set yourself up for the nutrient deficiency. In feeding experiments, the use of SPI (soy protein isolate) increased requirements for vitamins E, K, D and B12 and created deficiency symptoms of calcium, magnesium, manganese, molybdenum, copper, iron and zinc. She explains that this is because of high levels of phytic acid, enzyme inhibitors, lectins, manganese, and phytoestrogens. It has been shown that grain and legume-based diets high (which are inherently high in phytates) contribute to widespread nutrient deficiencies in third world countries. It turns out that the soybean has a higher phytate content than any other grain or legume, and because of the binding properties of phytates, soy products greatly inhibit zinc and iron absorption.

Trypsin is an important enzyme that is used to break protein down into its constituent parts, amino acids. A trypsin inhibitor is something that inhibits the action of the enzyme trypsin, or in other words, it deactivates it and may disrupt protein digestion.

To add to the mineral disrupting phytate content, soy protein isolate also contains trypsin inhibitors with content varying as much as five times between products. In rats, feeding results with even low-level soy protein isolate caused a reduction of weight gain compared to controls. Soy has also been implicated in contributing to fibromyalgia, no doubt, due to its many disruptive characteristics.

One quote (of many) says it all: “The treatments for fibromyalgia didn’t help at all. I stopped the soy immediately. Within 3 weeks, I was energetic, the muscle cramps started to melt away, and I was on my road to recovery.”

Eastern Cultures And Soy Consumption

As for those people who try to say that soy has been consumed for thousands of years and is used in huge amounts by Eastern cultures and look how healthy they are, blah, blah, blah. Do these people not consider that the health of Asian cultures, such as the Japanese, could be due to other factors such as Green tea consumption and an overall healthier diet than the average American?

They obviously don’t know that the soy plant was originally used as a nitrogen-fixing agent to help other crops grow (nitrogen is popular with plants as it is with bodybuilders). It wasn’t until the Chou Dynasty that soy began to be consumed, and even then, it was only after the discovery of fermentation techniques.

As for Asian cultures’ consumption of soy, it is actually lower than we have been lead to believe. Furthermore, the soy that is eaten in Asian cultures is usually in the form of fermented soya, which has been shown to be much healthier than popular soy protein isolates and phytoestrogens isolates. This includes TVP (textured vegetable protein), which is nothing more than dehydrated soy.

TVP is often used as a “healthy” filler in various processed foods and is very popular in school cafeterias to help cut the cost of such things like hamburgers, again being used as filler. It’s amazing how soy sneaks itself into our daily meals.

Soy caused enlarged organs in test animals. Most notably, the pancreas and thyroid gland where effected. Increased deposition of fatty acids in the liver was also reported. This effect could be due to a number of reasons ranging from soy’s hormonal influences to its tendency to bind essential vitamins and minerals or even one of the many toxins that SPI can contain.

An interesting aspect of SPI is in the way it is processed and what results in said manufacture. A potent class of carcinogens known as nitrites is formed during spray drying of SPI, and the toxin lysinoalanine is formed during alkaline processing.

Soy Isoflavones And the Endocrine System

I think that soy’s most profound and important influence isn’t necessarily on nutrient absorption, but in the way, it affects the endocrine system. According to researchers at the US Toxicological Laboratory in Arkansas, isoflavones (substances that are like estrogen and occur in abundance in the soybean) may actually be thyroid depressing compounds.

Does this make soy goitrogenic? Further evidence to support this idea comes from the University of Alabama at Birmingham, where reports of a case in which the absorption of thyroxine (an iodine-containing hormone produced by the thyroid gland; yes, it’s important) was decreased due to the consumption of a soy protein dietary supplement.

The subject of the case required oral doses of the thyroid hormone when consuming soy. Presumably, iodine ingestion was not a factor suggesting that iodine consumption did not stave off the goitrogenic effects of soy.

Soy has also been touted as an aid in menopause, but a study carried out at Monash University in Clayton, Australia showed that the daily ingestion of a soy supplement containing 188mg of isoflavones consumed for a period of three months did not improve menopausal complaints in 94 postmenopausal women compared with those taking a placebo.

The same conclusion can be found in a double-blind study carried out by the University of Milan, where patients were given 72mg of soy isoflavones or placebo. Both groups reported an identical decrease in the occurrence of hot-flashes showing that soy isoflavones were no better than placebo.

Indeed, the administration of soy isoflavones may have had many negative effects not monitored by the aforementioned studies.

Consider this quote from the March 5, 2003 edition of Psychopharmacology stated: “Isoflavones form one of the main classes of phytoestrogens and have been found to exert both oestrogenic and anti-oestrogenic effects on the central nervous system. The effects have not been limited to reproductive behavior, but include effects on learning and anxiety and actions on the hypothalamo-pituitary axis. Major changes in behavioral measures of anxiety and in stress hormones can result from the soya isoflavone content of rat diet. ”


This is but a small sample of all the evidence I found essentially proving that consumption of any non-fermented soy product is detrimental to many aspects of health. Furthermore, just to be fair and give soy a chance, I actually attempted to find some research that supported soy.

The funny thing is that I wasn’t able to find any credible sources claiming the health benefits of soy. There were, however, plenty of “studies” cited by various companies selling soy products.

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