Soy products and cancer – good or bad?

By Dr Janey

Soy, the ‘miracle New-Age food’, has reached virtually all the corners of the globe in recent decades.  It has been having a notable influence on breast cancer (and several other conditions).  But just what is the nature of this influence?  Anyone with cancer (or anyone who wishes to prevent it), should make a point of knowing the facts!

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When you delve into the controversy of whether soy products as a nutritional source are a good or bad thing, you begin to unearth a vast array of conflicting opinions.  These range from ‘best nutritional discovery on the planet’, to extremely harmful with ‘disastrous consequences for millions of people!’  It is little wonder that people are so confused as to what they should, or shouldn’t be eating!

So what is the truth and how does soy influence cancer?

The supporters of soy products enthuse about a food that is an inexpensive way to consume large amounts of an ‘ideal’ protein, while being very low in calories and fat, and with zero cholesterol. They add that it can prevent osteoporosis and cancer and is protective of the heart. They also point to the fact that in Asia where supposedly large quantities of soy products are consumed, the incidence of breast cancer is very low, and even go as far as to say that this ‘miracle food’ will save the world from starvation! High praise indeed!

So how did the soy phenomenon begin? Mary Enig PhD (lipid specialist and nutritionist) explains: “The reason there’s so much soy in America is because they (the soy industry) started to plant soy to extract the oil from it and soy oil became a very large industry. Once they had as much oil as they did in the food supply, they had a lot of soy protein residue left over, and since they can’t feed it to animals, except in small amounts, they had to find another market.” And so the human population became the vehicle in which to dump what is effectively a waste-product, after the soy oil has been extracted.

A dedicated soy marketing machine was engineered and a new multi-billion dollar industry was born! Now if this ‘miracle food’ was everything the enthusiasts make it out to be, then that would indeed have been a great breakthrough for mankind; however, as we begin to probe beneath all the layers of propaganda, a darker side to this ‘Cinderella of food’ is revealed!

As Mary Enig PhD and Sally Fellon go on to explain; the success in establishing a world-wide soy-eating trend is all the more remarkable when you realise that the soya bean was considered unfit to eat, only a few decades ago.

While the Chinese have eaten soy since the Chou dynasty (1134-246BC) this only began when they had learnt how to correctly ferment the soya bean in a manner that destroyed the large quantities of natural toxins or ‘antinutrients’ in soy which are harmful when consumed. Soy in Japan is fermented using traditional methods which take at least 2 summers, or ideally over 5-6 years, during which the soy toxins are destroyed and the nutrients preserved such that they can be utilised by the body.

Crucially however, soy is not fermented in this appropriate manner with the modern soy products we consume in the western world, and most significantly, we consume more than we ever thought we did! (more on that below)

Added to this, the natural toxins which remain in our ‘modern soy’ after inadequate fermentation, are not deactivated during cooking.

So just what are these ‘natural toxins’ in soy?

  • Phyto-oestrogens (isoflavones) with regards to breast cancer are perhaps the most relevant ‘antinutrient’ of them all! The high content of isoflavones in soy act as oestrogen agonists (ie they mimic oestrogen), and therefore contribute to our oestrogen exposure.

The important role of oestrogen in connection with the development and progression of breast cancer has been well established; quite simply, when we increase our exposure to oestrogen over our life-time through a number of different routes, we increase our risk to breast cancer! If for no other reason then, this single ingredient in soy is reason enough for any woman to avoid soy!

  • Phytic acid in soy effectively blocks the uptake of essential minerals in our diet, particularly calcium, magnesium, iron and zinc. Because of this, phytic acid has contributed considerably to the suffering from widespread nutritional deficiencies in 3rd world countries where they eat a large proportion of grains and legumes. In fact soy has one of the highest levels of phytic acid of any grain or legume! When we consume soy, the phytic acid blocks our absorption of calcium which contributes to osteoporosis (contrary to what the promoters of soy advertise); it also reduces our iron uptake which results in anaemia and reduced oxygenation of the cells (which plays a role in all chronic degenerative diseases including cancer). When the absorption of Zinc is blocked, it causes reduced fertility (Japanese wives are known to feed their husbands soy when they wish to reduce their virility!). Zinc is also the ‘intelligence mineral’ so important in brain and nervous system functioning. Deficiencies cause accelerated brain-aging and is linked to Alzheimers and dementia


  • Potent enzyme inhibitors in soy which block the enzyme trypsin, result in reduced protein digestion and absorption. It also causes pancreatic disorders including cancer.


  • Haemaggluttins in soy which cause the clumping of red blood cells increase the risk of blood clots and associated strokes, while also reducing oxygen uptake at the tissues contributing to many disease conditions.


  • Goitrogens in soy suppress thyroid function and in doing so predispose to hypothyroidism, a common thyroid dysfunction particularly amongst women (1 in 5 women can now expect to get hypothyroidism).

soy free

Added to this, the modern processing method of soy as used in western countries is highly damaging in the following ways:

  • It undergoes spray-drying at high temperatures which denatures the protein and renders it biologically unavailable (useless) to the body.
  • The soy is separated from the fibre using an acid wash which takes place in aluminium baths responsible for leaching large amounts of aluminium into the final soy product (aluminium is linked to Alzheimers)
  • During the spray-drying process, nitrites, which are potent carcinogens, are formed in the final soy product
  • Several artificial flavourings, including MSG (well known for its numerous adverse health effects!), are added to mask the ‘beany’ taste and impart a more ‘meaty’ flavour

Therefore in reality, while the soy enthusiasts talk of an ‘ideal protein’ and a food that promises to ‘save the world’, this is based on theoretical ‘qualities’ which are destroyed during the modern fermentation process while carcinogenic compounds are formed!


When pointing to Asia’s low breast cancer incidence as evidence of soy’s positive influence, the ‘soy fans’ are mistaken when they give soy the credit for this. Not only is the soy in Asia fermented over several seasons thus removing the natural toxins of soy as explained previously, but one also needs to take into account other important factors that contribute to low breast cancer levels in Asia such as the high vegetable/low meat diet consumed, higher activity levels and lower obesity levels to name a few. In addition, contrary to western assumptions, the Japanese and Chinese actually consume small amounts of soy – on average 10g (2 teaspoons) per day – and only as a condiment rather than as a meat replacement.

Back in the West, the marketing and promotion of soy has been relentless.  It is now being extensively incorporated into school lunch programs, diet beverages and many of our day-to-day food items. In fact if you think you don’t eat much soy, consider this; soy can be found ‘hidden’ in over 60% of our food products such as most supermarket breads, canned soups, pizza, cake mixes, muffins, chocolate, tortillas, canned tunas, some baby foods, hot chocolate, frozen foods and the list goes on…..


A few additional points to keep in mind:

  • Contrary to what the proponents of soy will tell you, the growing of soy is not good for the environment! Most soy is genetically modified and grown on farms that use pesticides that are toxic and carcinogenic. In addition, soy often takes the place of locally grown crops that are grown by the indigenous population thus transferring the value of processing to that of multinational corporations.
  • It is strongly advised not to feed infants any soy-containing products. The phyto-oestrogens are responsible for oestrogen levels equivalent to those children receiving over 5 birth-control pills per day! This results in a suppression of testosterone in male children, with resultant abnormal sex organ development; while in female children, it causes excessively early onset of puberty (often before 8 years of age) with resultant raised risks of breast cancer later on in life due to the prolonged life-time exposure to oestrogens. In addition, as a result of the endocrine disruptive nature of phyto-oestrogens, these children become prone to auto-immune thyroid disease as they get older. If that were not enough, the inhibition of protein enzymes causes poor protein absorption and stunted growth.
  • Vegetarians have often been encouraged to consume soy as a source of Vit B12. However the compound that resembles B12 in soy cannot be utilised by the body and in fact creates a greater requirement for this vitamin thus causing or exacerbating deficiencies. When you add to that the blocking effect of the minerals calcium, magnesium, iron and zinc, those vegetarians and vegans who replace their meat and dairy intake with soy products, risk suffering multiple severe mineral deficiencies!
  • Soy can cause severe, and in some cases, fatal food allergies. For those who tend to be allergic, avoiding soy may be a good place to start!
  • soy weakens the immune system

say no to soy

Avoiding soy however, isn’t always easy, but here are some tips:

  1. Eat fresh and unprocessed foods – soy can’t be hidden in natural foods!
  2. Use real butter instead of margarine or butter substitutes, all of which contain soybean oil
  3. Avoid microwave meals -many contain soy
  4. Avoid using vegetable oil (which usually contains soy oil as part of the mix). Instead use olive oil, coconut oil, flaxseed oil or hemp oil.
  5. Make your own healthy home-made muffins, bread etc; that way you know what has gone into them
  6. Avoid all canned and frozen foods wherever possible
  7. Avoid the list of food products known to contain ‘hidden soy’ as listed previously

As far as soy itself goes; avoid soy, soy milk and tofu completely! Only the soy products that have been fermented the traditional way in the east such as miso, tempeh and natto are fine in small amounts.


In summary, the introduction of modern soy and soy products in recent decades is having, and will continue to have, extremely hazardous effects on the health of millions of people unless we begin to educate ourselves and find the truth!

If you wish to prevent or treat cancer, or if you simply want to optimise your health, you must take steps to avoid intentional (and inadvertent) soy intake wherever possible….         it simply is not safe for human consumption!

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