Let me begin by saying that I am frustrated by the fact that it has become necessary to even write this paper. However, so much alarming foolishness has been purveyed over the past few years by pseudo-experts on the ‘horrific’ consequences of consuming soy that someone needs to set the record straight.
If you were to take the criticisms of soy at face value, and, unfortunately this is a real risk for the lay public, you would never know the truth. You might, in fact, believe that:
- Soy blocks thyroid function
- Soy prevents the absorption of minerals and vitamins and interferes with digestion
- Soy will promote breast and pancreatic cancer
- Soy is responsible for the real endocrine damage actually caused by the abundance of pseudo-estrogen toxins in the environment
- Men consuming soy will grow breasts
The reality is that none of these accusations are based upon verified facts. They have been generated, in many instances, by commercial interests threatened by the success of soy in the marketplace or by individuals seeking to build a reputation or garner attention through notoriety. But, even if the naysayers are sincere and simply misled or inadequately informed, their exaggerated criticism is not serving to advance the truth about soy.
Let’s take a look at the evidence of history. Millions of people over hundreds of years simply do not continue to consume significant quantities of a food that has devastating effects upon them or their posterity. The fact that soy consumption as a dietary staple has gone on for generations in large populations is the most compelling evidence that soy is not only safe but nutritious. This type of overwhelming epidemiological real world proof dwarfs any scientific study in importance but certain critics, who live in labs and not the real world, have missed this salient point.
Obviously, a product that has the versatility to allow it to be converted to oil for use in electrical transformers or into foam for extinguishing fires has the potential to be harmful, but no one, except a few fanatics, is suggesting that the soy used to produce printer ink or transformer oil is by any reasonable assessment, the same soy people eat!
There are over two hundred and fifty genotypes (varieties) of soy and, even if, you believe that the dangers of GMO manipulation are real, you don’t throw the baby out with the bathwater.
I am prepared to concede that the soy food products in the market place vary greatly in quality and value but none of them are poisonous or as noxious as the critics would have you believe. There are many that I would neither consume nor recommend but that is true of virtually all the food product lines available. For example, I believe we should eat meat and dairy products but I pick and choose among what is available, using reasonable selection criteria and that is the same type of vigilance I recommend to consumers of soy foods.
In my line of products, I use medical-grade soy and the isoflavones it contains are presented to the body accompanied by complete protein in a food and not solely with isolated amino acids. I do not recommend that soy isoflavones be consumed except in that manner.
I have over twenty years experience as a physician working primarily with human nutrition. I understand theoretical considerations but I work in the trenches with patients who have real health problems. I do not live in a lab and frankly, I am prepared to challenge those critics who are not involved in direct patient care, to keep your theoretical opinions to yourselves until they can be backed up with proof from the real world where I live and work with my patients.
I know a great deal about proteins and amino acids; how the body uses them and the real therapeutic value they have for patients struggling with disease. I want the best protein and amino acid sources for my patients and I have chosen soy after having worked extensively with other protein sources.
The State of the Evidence
I am not alone as the sole champion of soy as a useful medical food.
In 1999, The FDA allowed a heart health claim to be made for soy as a food. That decision was based upon the evaluation of all the available scientific research pertaining to soy up until that date. Additionally, numerous well-designed and competent studies also endorse the nutritional value of soy. In fact, soy may be among the most thoroughly investigated foods in the marketplace. There are over 10,000 papers on PubMed alone dealing with soy and its effects in a wide variety of health conditions including heart disease, cholesterol regulation, menopause, osteoporosis, cancer prevention and treatment, insulin sensitivity, recovery rates in athletes, asthma, pain control, metabolic syndrome etc… The overwhelming majority of these studies (I would underestimate greater than 95%) are positive and provide support for the benefits of soy and its isoflavones in humans.
There is certainly room for more study as more potential benefits of soy continue to emerge and, in the future, undoubtedly, a few diehard naysayers will continue to attempt to swim upstream against a current of positive evidence. Even God has detractors, but evidence is evidence and the rational mind should make judgments based on verifiable facts and not theoretical speculation.
On the website ‘clinicaltrials.gov’ (as of the 18th of January 2011) there were 180 ongoing trials for soy intervention in disease states. There is no question that enough evidence exists to come to the conclusion that soy is not some noxious deadly substance that people should avoid in all its forms. In fact, “the evidence from human studies does not suggest any worrisome adverse effects beyond mild gastrointestinal intolerance….”1
The Evidence Itself
Isoflavones are bioactive compounds, and recent studies find that the isoflavones contained in soy foods are associated with such benefits as improving the health of arteries,2 preventing certain cancers3, 4and reducing bone loss5. Unfortunately, there has been a lot of confusion resulting from a few studies in animals that were administered very high concentrations of isolated isoflavones compared to the bioactive compounds that one typically eats in soy foods. In some animal studies that were looking for adverse effects, investigators injected or fed a very concentrated source of one specific isoflavone, such as genistein, which is very different from the way isoflavones are consumed in food.6 Other problems seen in some animals but not humans are believed to be due to species-specific differences between humans and animals in the way soy isoflavones are metabolized.7
Isoflavones in soy based foods have no significant effects on hormone levels in men or women. (Isoflavones are not and should not be confused with the truly dangerous environmental toxins called phytoestrogens in petroleum-derived products.) Although soy isoflavones are called “phytoestrogens” because they share some of the molecular structure of estrogens, they act differently in the human body and should not be confused with the hormone estrogen. As a result, there is no validity to the claim that consuming soy leads to testosterone levels that are lower than normal. A recent study involving active young men found that soy protein did not lower testosterone concentrations in comparison to control groups. Soy protein did, however, produce a beneficial antioxidant effect.8 Other studies found that men consuming 40-70 mg/day of soy isoflavones from soy based foods or soy supplements had no significant changes in testosterone levels compared to control groups.9,10,11
Soy based foods are safe for the developing fetus. According to a scientific panel convened in March 2006 by the National Institute of Environmental Health Sciences (NIEHS), pregnant women who eat soy regularly consume such low amounts of genistein, the most heavily concentrated isoflavone in soy, that the likelihood of reproductive or developmental effects are of “negligible concern”.12 Potential problems have only been observed in targeted studies on animals, not humans, using very large amounts of isolated genistein.
Women who eat soy-based foods have a lower risk of developing breast cancer. Eating soy-based foods appears to have a protective effect against developing breast cancer at any age. This protection may be strongest when soy is consumed during childhood and adolescence.13,14 This could be a major reason why Asian diets are linked to lower breast cancer death rates. Observations have found that Asian women who follow a traditional Asian diet have a much lower breast cancer rate: in one estimate, one-fifth that of Western women15. And, when western premenopausal women eat soy, the estrogen exposure that leads to cancer is reduced16.
No studies demonstrate a link between eating soy and breast cancer recurrence or tumor growth in humans. Because some studies in mice observed that very high levels of soy protein or isoflavones led to faster tumor growth or recurrence, this has been an area of study in women, but no studies in humans have demonstrated a link between eating soy and tumor recurrence or growth. Nor has soy or its bioactive compounds been observed to cause certain changes associated with breast cancer, such as thickening of breast tissue,17,18,19, increasing the number of cells in breast tissue,20 or increasing estrogen circulating in the blood21. Researchers also make it clear that it is difficult to apply findings from animal studies using excessive doses of isoflavones to humans because mice and rats produce lower levels of hormonal estrogen than do women,22 and the digestion of isoflavones produces different end products23.
Soy based foods protect against thyroid cancer and have no effect on thyroid function in healthy people. A recent study indicates that eating soy based foods may actually protect against the development of thyroid cancer in women24. (More research needs to be conducted to determine if these benefits are consistent in men and women). In a recent review of clinical trials involving healthy men and women, the weight of the evidence found that consuming soy based foods or isoflavones had either no effects or only very modest changes (but still within normal range) on thyroid function25. It is important to note that the adults studied in these trials got enough iodine in their diet. In other studies or observations that linked soy based food consumption to goiter, iodine deficiencies, rather than soy, were to blame26.
Soy based foods are safe for people with hypothyroidism (under-active thyroid) who are under medical care. Soy based foods are among many commonly eaten foods, including high-fiber foods as well as iron and calcium supplements27 that have chemical components which can affect, to some extent, medication for hypothyroidism. Some physicians suggest taking the medication between meals, so that the chemical components in food do not interfere with the action of the medicine.28 This precaution is not unusual as many medication effects can be modified by food intake (ie. grapefruit and heart medications)
Traits of GMO Soy
While this paper is examining the traits of non GMO soy protein, it is important to note that most of objections raised regarding soy in general come from public perceptions and fears regarding genetically modified soy.
To help people understand how soy has been genetically modified, I have included the following material with links to more specific commentaries.
There are three main variants of GMO Soy listed below.
- Agronomic Traits
- Weed control
- Tolerance to herbicides is by far the most important commercial characteristic of GM-soya beans. Roundup Ready-soya beans (with resistance against herbicides containing the active ingredient glyphosate) have been grown for many years on a large scale particularly in North and South America. These areas account for about 60% of the world's soya bean production.
- Resistance to Pathogens
- Fungal resistance
- Nematode (worm) resistance
- Resistance against pests
- Insect resistance against the larvae of different types of butterflies and moths, as well as against aphids.
- Adaptation to Climate and Location Factors
- Tolerance to drought and salinity
- Quality Traits
Modified Composition of Components:
- Increased content of oleic acid (86% instead of 23%), and less linoleic acid. Because of the lower levels of linoleic acid, less trans fat, with its possible health risks, is formed when processing such strains of soya beans. These form at high temperatures, e.g. by hydrogenation of fats or by deep-frying. GM-soya beans with a higher content of oleic acid are predominant in the USA.
- Modified protein and amino acid content: e.g. enrichment with methionine. This amino acid is normally only found at low levels in soya beans and has to be supplemented if animals are fed solely on soy-based fodder.
- Reduced content of the polysaccharides stachyose and raffinose: stachyose is an oligosaccharide that cannot be fully digested by many domestic animals or humans. In the small intestines, stachyose is broken down by bacteria producing gas (flatulence). Different studies have shown that feedstuffs with a lower stachyose content enhance growth in pigs and poultry.
Enrichment with health-promoting ingredients, such as:
- sterols and stanols, secondary plant compounds that have a cholesterol lowering effect
- vitamin E
Removal of harmful substances:
Dangerous Misdirection by Soy Critics
As I close, I want to alert you to a truly unethical tactic adopted by some soy opponents. I will illustrate my point with a story.
One day, while walking in the mountains behind my home, I came upon a miniature combat scene. Three boys accompanied by a dog were at the edge of the trail vigorously throwing rocks at two other boys who had taken refuge behind a tree, perhaps 30 feet down the slope from the attackers.
I intervened with a few shouted injunctions and the boys ceased their attack. When I asked why they were throwing the stones, one pointed to the largest boy behind the tree and said: “He threw a rock at our dog!”
I then asked if both their targets had thrown a rock and they admitted that the smaller boy hadn’t. When asked why they were attacking him, they answered “Because he was with the guy who threw the rock.”
This story illustrates the guilt by association seized upon opportunistically by the opponents of soy.
A large number of petroleum-derived products, such as many plastics, contain serious toxins which can seriously affect the endocrine (hormonal) balance of the human body. These dangerous toxins are called ‘pseudo-estrogens’ and they act as anti-testosterones or estrogen imitators and are the probable cause of several alarming medical problems including premature female puberty, decreasing male infertility and malformations of the genitalia in newborn males which require surgery to correct.
For more information about these dangerous pseudo-estrogens I refer you to an excellent book entitled “Slow Death by Rubber Duck” and to a website titled “Tedex”.
Soy contains isoflavones which are plant compounds (often called phytoalexins) which plants elaborate as defenses against microbial attacks, (one well-known phytoalexin receiving a great deal of merited praise in the scientific press lately is resveratrol.) Because these phytoalexin/isoflavones bear a structural resemblance to the steroid molecule estrogen, they have been called phyto-estrogens not to be confused with the environmental toxins called pseudo-estrogens.
The actions of these two groups of compounds are strikingly different in the body. To pretend that soy isoflavones share the toxic qualities of pseudo-estrogens is both unjustified and unethical, yet some uninformed critics of soy do precisely that. Shame on them! There are beneficial estrogen-like elements and toxic estrogen-like elements just like there are good and bad estrogens. But let’s tell the truth!
Conclusion
Soy has justifiably been used for hundreds of years by millions of people as a nutritious food. Although soy critics attempt to distort even this historical evidence to serve their cause, the facts remain. Soy isn’t perfect but it definitely isn’t poisonous. Soy, in my opinion, is the best source for protein and amino acids to address multiple medical conditions. That’s what I do everyday. Unfortunately, I have had to divert significant time from my patient care duties to address soy’s critics.
I will conclude by issuing a challenge to the critics: “Come out from behind your laboratory test tubes and compare your clinical evidence with mine.”
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