The expansion of soy and its derivatives into the global market began in the 1990s. At that time, and even now, it was marketed as a revolutionary meat alternative with numerous health benefits.
The revolutionary product promised to lower cholesterol levels, ease the transition of menopause in women, protect against breast and prostate cancer, and also solve the problem of protein deficiency in the diets of vegetarians.
Years later, scientists confirmed the baselessness of almost all claimed health benefits of soy and even more – its exceptional harm to health.
Soy became incredibly popular solely due to savvy marketing that skillfully pressed on the most valuable sore spot for humans – their health.
This is one of the main conclusions that runs like a red thread through the book The Whole Soy Story, the facts of which formed the basis of this article.
Main thoughts:
The most common form of soy in modern food industry is soy protein isolate.
Starting as glue for cardboard boxes, the isolate has now penetrated sausages, breads, ice cream, sports nutrition, and baby formulas; it is a key component of most soy products that mimic the taste of meat and dairy products.
In bodybuilding, soy protein is often presented as an alternative to whey protein and there are some grounds for this, as the protein in soy is unique. And if it were only about the protein, soy protein isolate could indeed be called a revolutionary product.
The main problem with soy lies in the active substances in its composition that have toxic effects on the human body. The isolate inherits many of them despite the harsh technological processing and acquires additional ones due to it.
This article will discuss what soy protein isolate is, how it is made, and introduce 9 reasons for potential harm that many experts talk about.
What this article is based on
Many may not like the information presented below.
This is evidenced by numerous comments at the end, among which there are “dissatisfied” ones.
Therefore, it makes sense to clarify where the facts presented below come from, to indicate to whom any dissatisfaction should be directed in case it arises.
The foundation of this article is the materials from the book The Whole Soy Story: The Dark Side of America’s Favorite Health Food, which is a comprehensive study of the harm of soy and its derived products, including soy protein isolate.
(The book is available in an English paid version on amazon.com).
In the preface to the book, the author Kaayla T. Daniel notes some of the sources from which she drew information:
- professional translations of scientific publications from Japanese and other languages;
- full-text studies from scientific journals, including hard-to-access ones;
- correspondence with representatives of the soy industry and government organizations;
- documents obtained at significant financial cost and distress under the Freedom of Information Act;
- consumer reviews of soy products from men and women who suffered themselves or saw the sad results of feeding their children soy-based infant formulas.
A large number of scientists contributed to the writing of the book, some of whom made tremendous efforts to make the facts revealed in it public.
Others wished to remain anonymous, as the soy industry provides them with salaries, funds laboratories, and allocates budgets for the functioning of research departments.
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What is soy protein isolate?
Soy protein isolate is the result of the manufacturers’ persistent efforts to remove harmful substances for human health from soybeans, which give soy products their characteristic unpleasant taste, cause bloating, and hinder the absorption of protein and minerals, exerting toxic effects on the thyroid.
The composition of soy protein isolate contains 90-95% protein, which is obtained from soybeans through certain chemical manipulations.
Today, soy protein isolate is used in such a large number of food products that consumers are even unaware that its original purpose was far from that of the food industry.
In the 1970s, the Federation of American Societies for Experimental Biology (FASEB) concluded that the only safe use of soy protein isolate was as an adhesive for sealing cardboard boxes.
However, researchers were very concerned about the leakage of carcinogens nitrosamines and lysinoalanine (see below) from soy protein isolate at the sealing points into food products placed inside such boxes.
But ultimately, it was concluded that the amount of toxins entering food is negligible and does not pose a serious threat to health 27.
Soy protein isolate is an attempt by manufacturers to create the perfect product by removing harmful substances from soy for humans and animals.
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How Soy Protein Isolate is Obtained
Soy protein isolate cannot be produced at home.
Its production is a very complex high-tech process that takes place in chemical factories, not in kitchens. Naturally, it is completely unnatural, and the trendy term organic is weakly applicable to the final product.
Although it slightly differs among various manufacturers, and some keep their patented methods secret, the main steps are roughly the same for all.
First, soybeans are ground, dehydrated, and defatted.
The defatted soy flakes are then mixed with an alkaline solution to remove fibers (cellulose), after which they are washed in acid to separate the protein (as in milk curdling) and again in alkali to neutralize the acid.
The resulting thick mass is dried at high temperature and pressure, then ground into a powder with a high soy protein content 28-31.
The goal of such complex technological processing is to concentrate the protein and remove harmful toxic substances, which will be discussed below.
However, as will be shown below, natural toxins are not completely removed, and the harsh technological processing leads to the presence of substances that are no less harmful to human health in the isolate.
Additionally, the quality of the protein deteriorates.
Apparently, realizing their vulnerability, soy product manufacturers often mask its presence in products with elaborate names, the range of which is quite broad 32, while the word “soy” almost never appears in the list of ingredients:
- lecithin;
- natural flavoring;
- textured vegetable protein;
- hydrolyzed vegetable protein;
- vegetable oil;
- mono-diglyceride;
- soya, soja, yuba;
- TFS (textured soy flour) and TSP (textured soy protein);
- TVP (textured vegetable protein);
- MSG (monosodium glutamate).
To obtain soy protein isolate, soybeans are subjected to acids, alkalis, and high temperatures. As a result, natural toxins in soy are not completely removed, new harmful substances for health appear, and the quality of the protein deteriorates.
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Pros and Cons of Soy Protein Isolate
The scientific community is very polarized on the benefits and harms of soy and soy protein isolate. It can be confidently said that this is one of the most controversial products in the world of modern catering.
Soy protein isolate indeed has both pros and cons. What outweighs what – it’s up to you to decide.
A significant advantage is its high protein content, the amino acid profile of which is unique among all plant proteins, as it contains all the essential amino acids needed by humans.
How good is this protein? We’ll discuss it below.
This “plus,” along with the low content of saturated fats (harmful to the heart), is often what supporters of soy and soy protein have in mind when talking about their health benefits.
This is hard to dispute, and it is indeed true.
Scientists from the opposing camp focus on the downsides of soy protein isolate – the presence of toxic substances, both natural and those that appear during the harsh technological processing.
“Why be so pessimistic, isn’t it better to think positively and enjoy life?”
Numerous studies indicate that the anti-nutrients in soy deserve special attention.
“The main problem with soy is that nowadays we consume it much more than before, especially in the form of soy protein isolate – a result of deep technological processing of soy,” says dietitian Stephanie Middleberg 1.
“And if at first glance we see a plant-based natural product, in reality, it is something very far from natural authenticity.”
The fact that industrial processing disrupts the consumer properties of natural products is not something characteristic exclusively of soy protein isolate.
Here for example, we discuss the harm of one of the most popular proteins in sports – casein. The reason is the same: the production technology.
Facts About the Harm of Soy Protein Isolate
Important note.
In the following text, when describing the harmful facts of soy protein, you will sometimes encounter the alternating terms “soy protein isolate” and “soy.”
This is valid regarding the isolate, as it inherits almost all characteristic harmful properties of soy associated with the presence of natural toxins in it.
Of course, the degree of manifestation of some of these properties in the isolate is lower, as the content of dangerous substances from soy is significantly reduced during production.
However, similar to medicines and poisons, certain substances can be harmful even in very small concentrations.
1 Most soy protein isolate is made from genetically modified (GMO) soy
More than 90% of the soy grown today in the world is genetically modified. This means that the unclear, yet already familiar three-letter abbreviation is also inherited by the soy protein isolate.
A logical question arises: what is dangerous about GMO soy and why are its genes modified?
Reason for the harm of GMO soy
Have you ever wondered why genes are modified in different products?
In the case of soy, it makes it resistant to the herbicide Roundup, which is used to kill weeds.
What does this mean for us, the consumers?
The active ingredient of the herbicide Roundup, glyphosate, when entering the human body, disrupts the hormonal balance in the bodies of women, men, and children 19.
It affects aromatase – an adrenal enzyme involved in the production of the female sex hormone estrogen.
Glyphosate is toxic to the placenta, through which nutrients are delivered from the mother’s body to the child’s body and harmful substances are filtered out. When the placenta is damaged, the fetus is harmed.
Children born to mothers who have been exposed to Roundup even in small doses may have very serious congenital defects.
Want an example?
The author of one of the large studies on the harm of pesticides, Dr. Andres Carrasco, describes what happens to amphibian embryos when they are exposed to Roundup at doses significantly lower than those used in agriculture (diluted 5000 times) 19,20,21:
“The observed side effects include reduced head size, genetic changes in the brain, increased cell mortality from which the skull forms, deformed cartilage, eye defects, kidney development disorders. Moreover, glyphosate is not excreted from the body but accumulates in cells.
Similar disorders are observed in human embryos exposed to this chemical.”
Regarding humans, the scientist concludes that the high incidence of cancer, congenital defects, high fetal mortality, skin tuberculosis, kidney diseases, and respiratory diseases among the population of Argentina living near fields where soy is grown may be linked to the use of the herbicide Roundup19.
In April 2010, Russian researchers from the Academy of Sciences found that feeding GMO soy to hamsters for 2 years resulted in infertility in the third generation8.
Their conclusion:
“It is quite likely that it is not the GMO soy itself that is the cause… It could be chemical contaminants, herbicides present in the soy, and Roundup in particular.”
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Is the herbicide Roundup in soy a problem only for America or for the whole world? Including Russia?
Europe imports about 38 million tons of soy annually, most of which is used for animal feed. Of this, 50-65% is GMO, the rest is non-GMO 19.
In one analysis of 179 soy products on store shelves in Germany, the presence of GMO soy resistant to the herbicide Roundup was found in 34 of them 22.
Kaayla T. Daniel, author of The Whole Soy Story, notes an interesting fact regarding China:
“China – one of the Asian countries from which the USA borrowed the idea of using soy as food, is now one of the main importers of soy products… from the USA” 23, which is 95% GMO…
And what about Russia?
In Russia, there are indeed farms that grow natural (non-genetically modified) soy. I personally know a farmer known for his honesty who confirmed this to me. Of course, it is likely that not all do this.
Again, note that in the above study with hamsters, Russian scientists point to the herbicide Roundup present in soy as a possible cause of rodent infertility… and where there is Roundup, there is also GMO.
Now let’s answer a simple question: “Does it even matter to us how soy is grown in Russia?“
After all, the overwhelming majority of gainers, protein bars, and soy proteins that are on the shelves of sports and health food stores in Russia, Belarus, Ukraine, Kazakhstan, and that are popular among consumers are imported brands, German and American, which we somehow trust more…
Moreover, Russian manufacturers of sports nutrition openly state that they use foreign raw materials 24.
The harm of GMO soy and the soy protein isolate produced from it lies not in the alteration of molecular structures, but in the presence of toxic chemicals harmful to humans, which are used to combat weeds and inevitably end up on the consumer’s table.
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2 The consumption of soy protein isolate by women leads to infertility
The information provided below is important for every woman to know, especially those who cannot conceive, have irregular menstrual cycles, or are trying to combat menopause symptoms with soy phytoestrogens.
Scientists first spoke about some plants having hormonal effects in connection with the so-called clover disease in sheep: sheep that fed on clover could not conceive.
The reason was phytoestrogens – plant analogs of the female sex hormone, which are found in large quantities in soy.
Sheep that fed on clover exhibited endometrial damage: the inner layer of the uterus thickened, preventing menstrual flow from exiting, which provoked pathological processes.
Later, similar problems were found in domestic birds, cows, mice, cats, dogs, and humans 33-45,46.
Phytoestrogens are found in more than 300 plants, of which only soy is consumed by humans in large quantities.
The consumption of soy protein isolate by women (especially GMO), as well as other soy products (soy milk, “soy meat”) can lead to serious hormonal changes, including increased estrogen levels, damage to the pituitary gland and thyroid, menstrual irregularities, stimulation or suppression of hormones responsible for sexual function and the ability to conceive, and disruption of fetal development in pregnant women.
Today, scientists say that the widespread consumption of soy and its products may be one of the likely causes of female infertility in our time.
Look at the results of the following illustrative study.
In it, six women consumed 60 g of “soy meat,” containing 45 mg of isoflavones, for 30 days.
As a result, their menstrual duration increased, the level of luteinizing hormone decreased by 33%, and follicle-stimulating hormone decreased by 53%. After stopping the consumption of soy protein, the effect lasted for another three months 47.
These data clearly indicate that soy products at least disrupt the menstrual cycle and significantly negatively affect the ability to conceive.
Both mentioned hormones are gonadotropins, i.e., they stimulate the sex glands: in men – the testes, in women – the ovaries. The lower the level of these hormones, the lower the chance of conception.
Consuming soy and soy protein isolate can lead to heavy menstrual flow and increased duration. This condition is called menorrhagia.
Some pharmaceutical companies have even invented special pills for its treatment, although in some cases, it is sufficient to make adjustments to the diet.
But the negative side effects of soy protein isolate are not limited to women.
In the bodies of women who consume GMO soy, hormonal changes occur, and their risk of infertility significantly increases.
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3 The consumption of soy protein by men reduces libido, can lead to erectile dysfunction, and cause breast growth.
As with women, scientists first encountered the problem of the influence of phytoestrogens, which are found in soy and soy protein isolate, in the case of the same sheep described in the previous section.
Researchers found that male sheep fed clover had significantly reduced sperm volume and exhibited some other sexual deviations.
Healthy males became infertile by the time of sexual maturity, while castrated males had enlarged nipples and secretions 48,49.
Historically, it is known that monks in some monasteries in Asia consumed (and still consume) soy products to reduce libido (sexual desire), which was a desired effect for them.
There is also a suggestion that Japanese wives could take revenge on their husbands for marital infidelity by increasing the daily dose of tofu… 50,51
What does this have to do with soy protein isolate? Directly.
The likely cause of such sexual function disorders lies in two natural “medications” found in soy – the isoflavones genistein and daidzein, which belong to the class of phytoestrogens that mimic the action of the female sex hormone estrogen.
With a chronic increase in estrogen levels, a whole range of side effects may develop in men:
- breast enlargement;
- decreased facial and other “male” body hair growth;
- decreased libido;
- mood changes;
- erectile dysfunction;
- reduced sperm volume.
The content of phytoestrogens in soy protein isolate, as will be shown below, is NOT zero.
When consuming phytoestrogens, the level of the female sex hormone estrogen in the blood increases, which directly or indirectly affects testicular function, the level of gonadotropins in the blood (hormones that regulate the synthesis of sex hormones), or testosterone concentration in the blood 52.
Scientific studies confirm the fact of reduced testosterone levels and increased estrogen in men consuming soy products 53,54, as well as an increase in breast size and the appearance of secretions from them 55.
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A curious clinical case is as follows.
In one experiment, scientists recorded abnormal breast growth in a 60-year-old elderly man, complete loss of erection, and a fourfold increase in estrogen levels as a result of consuming 3 liters of soy milk per day 9.
After stopping the intake, the indicators gradually returned to normal.
– Hey! But he’s an old man! And that’s three liters!
True. But I repeat: the cause lies in the phytoestrogens. The determining factor is their quantity in the diet.
Do you know how much you consume throughout the day along with protein, soy burgers, and milk?
The content of phytoestrogens in various soy products varies widely. In soy protein isolates from different manufacturers, it ranges from 47 to 199 mg per 100 g.
– Should men completely exclude soy protein isolate from their diet?
It all depends on how much you consume of it and other products containing phytoestrogens.
Monks consume soy to reduce sexual desire (libido). Soy protein isolate may be the cause of breast growth in men, decreased testosterone levels, erectile dysfunction, and infertility.
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4 Soy protein isolate lacks many important micronutrients
Soybeans are a good source of protein, containing all the essential amino acids (just like meat), fiber, minerals, and complex carbohydrates.
However, during the production of soy protein isolate, the protein is chemically isolated, and along with it, many other beneficial nutrients that are present in whole soybeans are removed 1.
5 Soy protein isolate contains harmful chemicals and carcinogens
During the production of soy protein isolate, it is “enriched” with certain chemicals that are toxic to humans and may promote the development of cancer and other diseases.
Aluminum
One of the known issues is the presence of aluminum in the isolate.
Aluminum in the human body affects the function of the nervous system. Its excess is a factor in the development of dementia, memory loss, confusion, disorientation, coordination disorders, and some digestive disorders.
It also disrupts calcium absorption and leads to increased brittleness of bones 56-58,
Aluminum enters soy and soy protein isolate through several pathways:
- naturally, from the soil into soybeans;
- unnaturally, during the manufacturing process.
In production, sources of aluminum include certain food additives (leavening agents, iron minerals, compounds of fluorine, calcium, potassium that enhance aluminum absorption), water, aluminum containers and storage bins, and foil packaging 59-62.
The aluminum content reaches particularly high levels in soy protein isolate: in infant formulas based on it, the concentration of aluminum can exceed 100 times its concentration in breast milk.
There is a clear pattern: the more high-tech the manufacturing process, the more aluminum appears in the final product.
This is true not only for soy protein isolate but also for whey protein, casein, and other types of products.
Thus, whole cow’s milk contains less aluminum than whey protein, while in hydrolysates of whey protein or casein or soy protein, its concentration is very high 63-66, 67.
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Chemical Toxins and Carcinogens
During the production of soy protein isolate, dangerous toxic substances and carcinogens can form as a result of exposure to acids, alkalis, and high-temperature drying.
Among them 68:
- nitrosamines;
- lysinoalanines;
- heterocyclic amines;
- excitotoxins;
- chloropropanols;
- furanones;
- hexane;
- and others.
We will only touch on the first two from this list: nitrosamines and lysinoalanines.
Nitrosamines are highly active chemical substances that have a damaging effect on the liver in the human body and are mutagens and carcinogens 69-71.
The potential harm of nitrosamines (as well as other toxins) is determined by how much of them enters the body or by the amount of soy protein isolate consumed.
Vegetarians, whose diet is based on soy meat substitutes, soy protein bars, milk, and other products, may consume toxin levels exceeding the FDA’s recommended safe amount by 100 times 71.
In a study conducted in the 1980s by the United States Department of Agriculture (USDA), scientists found that the nitrite content in soy protein isolate is twice that of other soy products, which is a result of multi-stage rigorous processing 72.
According to some estimates, a person who consumes 100 grams of soy protein per day may exceed the recommended safe dose of nitrosamines by 35 times 73.
Lysinoalanines are compounds of several amino acids that are formed when the essential amino acid lysine is subjected to the action of an alkaline solution.
Lysinoalanines are found in the highest concentrations in soy protein isolate, as alkaline solutions with very high pH are used in its production. This allows for the separation of soy protein and the removal of the unpleasant bean taste 74-78.
Rats that were fed soy protein made using alkalis with such high pH exhibited kidney damage and other organ issues, increased organ size, and the formation of kidney stones 74-77.
Food Additives
It is also important to realize that the meat flavor in soy products and cow’s milk in soy milk, as well as its white “cow” color, is achieved by adding artificial food additives, many of which are harmful to humans 79,80.
These additives also help to mask the strong characteristic unpleasant taste of soybeans and provide a pleasant desired aroma.
In the composition of soy protein isolate, aluminum, nitrites, and artificial food additives that pose health risks to humans can easily be found.
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6 Soy protein isolate contains isoflavones – an analogue of the female sex hormone estrogen
Soy isoflavones are a plant analogue of the female sex hormone estrogen (phytoestrogens).
They are attributed with most of the “beneficial properties” of soy: anticancer effects, benefits for cardiovascular health, combating osteoporosis, etc.
Scientific research on the benefits and harms of isoflavones is very controversial and indicates a high likelihood of the following health issues with regular consumption:
- disruption of thyroid function;
- increased risk of breast cancer, thyroid cancer, leukemia in children;
- development of infertility in girls, developmental pathologies of the reproductive organs in boys;
- disruptions in sexual function in adult men and women;
- and more.
For us, the important question is: do isoflavones exist in soy protein isolate?
Yes.
Their concentration varies significantly from manufacturer to manufacturer and is in the range of 45-200 mg per 100 g 6 (a table of isoflavone content in various soy products is provided in our material on the benefits and harms of soy isoflavones).
Is this a lot or a little?
For middle-aged women, 45 mg is sufficient for thyroid dysfunction. And even after discontinuing its use, the effect may persist for several months 7,16.
In comparison, the dose of isoflavones in soybeans can reach 120 mg per 100 g.
The discrepancy in both cases is explained by the fact that the growing conditions of soy and the method of its technological processing have a significant impact on their concentration 5.
Research indicates that soy isoflavones inhibit the synthesis of steroid hormones in the body, which are responsible for muscle growth and the formation of sexual differences in boys and girls.
This is important for athletes who consume soy protein isolate in an effort to increase muscle mass.
The content of isoflavones in soy protein isolate may be higher than in raw soybeans. Isoflavones have a complex effect on the body, inhibiting the synthesis of steroid hormones, affecting thyroid function, and increasing the risk of certain forms of cancer.
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7 Phytates in soy protein lead to mineral deficiencies
Soybeans contain high concentrations of phytates (phytic acid), which lead to deficiencies of important minerals as they inhibit their absorption: calcium, magnesium, copper, iron, and especially zinc.
Interestingly, a plant-based diet is generally rich in these minerals and other vitamins, but when consumed together with phytates, the latter block their absorption.
This fact is particularly important for vegetarians and vegans, for whom soy and products made from soy protein isolate are primary sources of protein.
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The phytate content in soy is among the highest of all plant foods. Thermal processing, even prolonged, does not completely destroy them.
In animal studies, when soy protein isolate was used as feed, it was found that the need for vitamins (E, K, D, B12) increased, as well as mineral deficiencies (calcium, magnesium, manganese, molybdenum, copper, iron, and zinc) 13, internal organs increased in size, particularly the pancreas and thyroid gland, and there was an increase in fatty acid deposition in the liver 14.
Phytic acid is referred to by scientists as one of the reasons for the low nutritional value of soy and its derived products.
– What does this have to do with soy protein isolate?
It is believed that during the production of soy protein isolate, most of the harmful substances in soy are removed. This is not entirely true.
The content of phytates in the isolate can differ by 5 times among different manufacturers 10.
What is important is that even a small amount of them has a negative effect: experiments on rats, for example, have shown that even a small amount of their presence in a diet based on soy protein isolate led to a decrease in the rate of muscle mass gain 11.
Interestingly, there is a technology for almost complete neutralization of phytates in soy protein isolate, but it is quite expensive, which is why most manufacturers neglect it 81.
From an economic point of view, it is much more profitable for the manufacturer to enrich soy products with trace elements, the risk of deficiency of which increases for those who consume soy products: zinc, iron, calcium, etc.
That is why the packaging of children’s soy formulas, soy milk, and soy protein isolate always includes an extensive list of vitamins, minerals, and amino acids that have been added to them.
This is perceived by us, the consumers, as an advantage (ask yourself the question, which milk will you buy: regular or calcium and vitamin D enriched?), while in reality, it indicates the inadequacy of the product itself and the presence of toxic substances in it.
Soy protein isolate contains phytates that inhibit the absorption of minerals even in very small concentrations
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8 The protein in low-quality soy protein isolate is degraded
Soy differs from other legumes by having the highest protein content: 35-38 grams per 100 grams compared to 20-30 g in others 82.
In soy protein concentrate and isolate, the protein content is even higher, reaching 70-90 g per 100 g, as almost all fat and carbohydrates are removed from them.
Additionally, soy protein is unique among all plant proteins, as it contains all the essential amino acids required by humans, which is not typical for plant products in general.
But how quality is the protein in soy protein isolate?
The quality of protein is determined not only by the presence of all essential amino acids needed by the human body but also by their ratio and availability (absorption).
The deficiency of even one essential amino acid is a significant problem and can halt our entire internal laboratory that sustains life, as it leads to disruptions in the synthesis processes of digestive enzymes, antibodies (which provide immunity), muscle proteins, and hormones.
It is dangerous not only to have a complete absence of one or several essential amino acids but also to have their intake in insufficient amounts.
In the case of soy protein, we have two problems:
- one of the essential amino acids – methionine – is present in limited amounts;
- the process of producing the isolate deteriorates the quality of the protein.
The deficiency of methionine is a common issue characteristic of all legumes. This is a fact.
That is why manufacturers of sports proteins and children’s formulas based on soy protein isolate almost always enrich their products with this amino acid.
Methionine is known for its role in supporting body growth and many athletes take it as a supplement for even greater stimulation of muscle growth. How justified is this? It’s a controversial question.
During the production of the isolate, at the stage of high-temperature drying, there is partial destruction (denaturation) of the protein, and consequently, its biological value decreases, making it less effective for muscle mass gain for athletes and for growth in children 12.
For this reason, farmers who feed animals with soy feed necessarily add dietary supplements in the form of individual amino acids (in particular, lysine) for normal growth.
The content of lysine decreases due to the formation of the toxin lysinalanine, which was mentioned earlier.
According to some data, in soy protein isolate, the concentration of the amino acid lysine decreases by ~20%, cysteine by 73-77%, threonine by 35-45%, and serine by 18-30%.
Moreover, the natural forms of some amino acids can be converted into isomers that are useless 83.
All of this combined leads to a significant reduction in the quality of protein in soy protein isolate compared to soybeans.
Popular methods for assessing protein quality provide the following values for soy protein isolate:
- biological value – 74 (whey protein – 100, whole egg – 100, egg white – 88, casein – 77) 84,85;
- PER – 70 (casein – 100, beef protein – 82) 86;
- PDCAAS – 100 (casein – 100, egg protein – 100).
Overall, the quality of soy protein (reflecting the degree of absorption and effectiveness) is lower than that of animal proteins.
The high rating according to the PDCAAS method is explained, according to the author of The Whole Soy Story, by the fact that this method was specifically developed with the involvement of soy product manufacturers to position soy protein alongside its main competitors (eggs, whey protein, and casein) 87,88.
The protein in soy protein isolate is of low quality: the amino acid profile and degree of absorption are significantly reduced during harsh technological processing.
9 Active substances in soy protein isolate hinder protein digestion
Many people experience allergies to soy and soy products, as well as digestive difficulties.
But even if this is not your case, soy protein isolate contains substances that block the action of trypsin – a digestive enzyme necessary for protein digestion. These are called trypsin inhibitors.
These are large, tightly folded proteins that are not completely broken down during normal cooking. They can cause serious stomach disorders, poor protein digestion, and, consequently, some diseases related to protein deficiency in the body.
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In soy protein isolate, a significant portion (80-90%) of trypsin inhibitors is neutralized. However, the content may vary significantly among products from different manufacturers.
Research has found very high concentrations of them in some infant soy formulas and soy protein concentrates 89-94.
The presence of trypsin inhibitors in food leads to an increase in the size of the pancreas.
This is explained by the fact that this gland is responsible for producing trypsin; since the inhibitors bind this enzyme, its concentration in the small intestine decreases, signaling it to produce more of this enzyme.
The need to work in overdrive over time leads to an increase in the size of the pancreas, both due to the enlargement of cells and their proliferation 95.
This, in turn, increases the risk of developing pancreatic cancer 96-107.
In soy protein isolate, there are inhibitors of the digestive enzyme trypsin, which hinder the digestion and absorption of protein. This may lead to the development of pancreatic cancer.
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If the isolate is so bad, how do we explain the “Asian phenomenon”?
Scientists who defend the benefits of soy protein isolate often argue their position by stating that Asians, whose diet is based on a large amount of soy products, suffer less from breast, uterine, and prostate cancer.
This may be true, but they deliberately omit two important facts (by the way, many such “scientists” receive private funding from soy product manufacturers, who, of course, do not want bad results):
- the same Asians, especially the Japanese, have a lower risk of the aforementioned types of cancer but are much more likely to suffer from esophageal, thyroid, stomach, pancreatic, and liver cancer 111,112;
- Asians primarily consume fermented soy – the only type of soy that has any health benefits.
The reason for the higher risk of some forms of cancer and the lower risk of others is the same – UNfermented soy 108-110.
Marketers often intentionally overlook this fact. But agree, for end consumers, there is not much difference between types of cancer – it is frightening in any manifestation.
So, what distinguishes fermented soy from unfermented?
Popular claims about the benefits of soy and soy protein isolate for preventing osteoporosis, cardiovascular diseases, senile dementia, prostate, tongue, and liver cancer are true, but ONLY for fermented soy products 108.
Why?
During fermentation, most of the health-harmful toxic substances in soy are broken down. However, the content of isoflavones remains unchanged.
Additionally, this soy is enriched with vitamin K2, which acts synergistically with vitamin D and has anti-cancer protective properties, positively affects blood viscosity, and specifically protects against osteoporosis and heart diseases 108.
The fermentation process removes most of the health-harmful natural toxins from soy, but does not change the content of isoflavones in soy!
Examples of fermented soy products:
- Tempeh: fermented soy cake with a firm texture and a nutty and mushroom flavor.
- Miso: fermented soy paste with a salty, buttery texture (usually used in miso soup).
- Natto: fermented soybeans with a sticky texture and a strong cheese-like aroma.
- Soy sauce: traditionally made from fermented soybeans, salt, and digestive enzymes, but nowadays produced chemically (stay away from them).
As can be seen, tofu is absent from the list – it is an unfermented soy product.
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An interesting study on the “benefits” of soy protein isolate
The facts mentioned above and many other facts about the harm of soy protein isolate do not prevent its widespread use today in the production of sausages, commercial baked goods, dietary drinks, baby formulas, and instant products, as well as in school lunch programs in the USA.
Despite poor test results of the isolate as animal feed, the soy industry sponsored a number of studies aimed at showing that soy products can be used in human diets as a replacement for traditional foods.
One such “evidence” is the “Nutritional Value of Soy Protein Isolate: Studies in Preschool Children,” which was funded by Ralston Purina Company 15.
In the study, a group of malnourished children from Central America was initially fed natural foods suitable for them to improve their condition: meat and dairy products. Then, for two weeks, these traditional foods were replaced with a drink based on soy isolate and sugar.
As a result, it was “found” that such nutrition contributed to maintaining nitrogen balance and provided adequate growth. The result was deemed a “success.”
The experiment did not demonstrate what impact a diet based on soy protein isolate has on health and what effect it has in the case of long-term consumption.
Researchers noted that “from time to time” the children experienced vomiting, usually after meals; that most suffered from diarrhea, some had upper respiratory infections, and others had rashes and fever.
It is also noteworthy that the researchers did not dare to use soy products to help the children recover from malnutrition in the first stage, and they were forced to supplement the soy-sugar mixture with vitamins and minerals that are largely absent in soy products: vitamins A, D, and B12, iron, iodine, zinc.
Many studies on the benefits of soy protein for human nutrition are fictitious and funded by commercial entities.
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The harm of infant formulas based on soy protein isolate
Infant formulas made using soy protein isolate are recognized as one of the most dangerous products for feeding newborns.
Consider the meaning of the following fact 17.
In a study on the harm of soy infant formulas conducted in 1998, scientists noted that “the concentration of isoflavones in them exceeds (when adjusted for body weight) that which produces hormonal changes in the bodies of adults consuming soy by 6-11 times.
In other words, the concentration of isoflavones in the blood of infants on soy formulas exceeds the level of estradiol (female hormone) in the blood of infants fed cow’s milk by 13,000-22,000 times.”
The consequences of feeding such a formula include 113-131:
- early sexual maturation in girls and gynecomastia (breast growth) in boys
- infertility;
- food allergies;
- asthma;
- behavioral disorders;
- thyroid diseases;
- cancer.
Infant formulas also inherit common issues associated with soy protein isolate: contamination with aluminum and herbicides.
According to some researchers, children fed soy infant formulas receive a dose of estrogen equivalent to several contraceptive pills that adult women use to prevent pregnancy. See the material on the harm of soy.
Children who are fed infant formulas based on soy protein isolate receive a dose of estrogen equivalent to several contraceptive pills.
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Afterword
Soy protein isolate was supposed to be a source of high-quality plant-based protein, a foundation for the nutrition of vegans/vegetarians, children with lactose intolerance, athletes, and people at risk for cardiovascular diseases, osteoporosis, and cancer.
However, the process of its production significantly deteriorates the quality of the protein in it and not only does NOT completely remove harmful toxic substances from soy, but also “enriches” the isolate with new harmful ingredients, including carcinogens, chemical toxins, and aluminum.
The content of soy isoflavones in soy protein isolate also does not decrease, and may even be several times higher than in the beans.
In summary, all this means that the consumption of isolate (as well as soy) increases the risk of micronutrient deficiencies, the development of infertility in women, sexual dysfunction in both men and women, as well as the development of cancer and the birth of unhealthy offspring.
The soy protein isolate is not very suitable for muscle mass gain in bodybuilding due to its low content of the amino acid methionine and poor protein quality.
