Will soy give you breast cancer or protect you? Will soy produce breasts in young boys? Protect girls from ever increasingly early onset of puberty? Does it speed up breast cancer, or make a useful contribution to both preventing and recovering from it? Does it really protect from difficulties during menopause?
It seems some people would have us believe soy is full on toxic. Others point to the low rates of breast cancer and menopausal difficulties in Asian women, link this to their regular soy consumption and suggest soy is something we would all benefit from.
So this is to revisit an earlier post on these matters that was evidence-based. To re-examine the science behind soy and breast cancer so we can bring some logic and clarity to this often steamy debate. Then I will tell you what Ruth and I actually do, and not shirk from drawing 3 compelling conclusions and making recommendations, but first
Thought for the day
Meditation (reflection) first purifies its own source, ie, the soul, from which it arises.Then it regulates the inclinations, directs activity, moderates excess, shapes morals,
Makes life honest and regulated,
And mediates knowledge of divine as well as human things.
It is this which replaces confusion with order,
Checks the inclination to lose oneself in uncertainty,
Gathers together that which is dispersed,
Penetrates into that which is hidden,
Discovers that which is true and distinguishes it from that which merely appears as such,
And brings to light fiction and lie.
St Bernard of Clairvaux
Soy products have gained widespread popularity in the West over the last 50 years. But whether they are really safe, and especially what to recommend in regard to breast cancer has been an issue of great contention this last decade. It is an area I have taken a great deal of interest in. I have read widely, spoken to many authorities and fielded many questions.
What follows then is a major piece that is evidence-based and comes in two parts, much of which first appeared on this blog in July and August of 2013, and now seems to warrant a re-run. This is the first blog I have repeated, albeit with some important research updates since one year ago.
The aim is firstly to bring further understanding to the soy bean itself. Particularly when it comes to nutrition, I am of the view that if we can understand the principles, then the details follow fairly simply and we will have the confidence to make good choices.
And then in Part 2, how does soy interact with breast cancer? Does it cause or prevent breast cancer? And what of its role for those who have developed breast cancer – does it help or hinder?
As it seems the answers to these questions may well vary depending upon what type of soy foods we eat, let us begin by understanding the range of options available.
THE SOY BEAN (Glycine max)
3 Forms – raw, traditional, processed
1. The raw soybean (or soya bean as it is called in the UK) is a legume that originated in East Asia but is now classified as an oilseed rather than a pulse by the FAO. There are 2 main types, those used for eating (which make up about 15% of world production), and those for oil (85%).
Raw soybeans contain trypsin inhibitors that make them toxic to humans and all other monogastric (single stomached) animals.
Happily, cooking with "wet" heat destroys the enzyme and solves this problem, so all edible forms of soy have been, or need to be cooked.
2. The traditional use of soybeans falls into 2 categories:
i) Non-fermented foods including tofu, tofu skin and soy milk.
ii) Fermented foods including soy sauce, miso (fermented soybean paste), and tempeh.
Fermentation does lower the phytoestrogen content found in the raw beans. People have claimed that historically soybeans were only used after fermentation, and we shall investigate whether or not this would seem to be a relevant issue.
3. Processed soy products are a more modern phenomena and usually stem from soy flour (made by roasting and grinding the beans) and its products.
One of the most common is TVP (Texturized Vegetable Protein – a similar form of which can be made from wheat, oats and cotton seeds). TVP is a de-fatted soy flour product that is a by-product of extracting soy oil. It has a protein content equal to that of meat and is often used as a meat substitute or extender.
Fat-free (defatted) soybean meal is a significant and cheap source of protein for animal feeds and many prepackaged meals.
Processed soy may be found in many things from vegetable sausages to Mars bars.
SOY BEAN FACTS
GMO
In 1997, about 8% of all soybeans cultivated for the commercial market in the United States were genetically modified. In 2010, the figure was 93%. Unless a soy product stipulates that it is GMO free, or organically grown, it is almost certain to contain at least some genetically modified beans.
Soy oil
Soy beans have a high oil content; around 20% and soy oil accounts for about 65% of all oil used in commercial and home cooking. However, soy oil is low in Omega 3 fatty acids and high in Omega 6s. The ratio of Omega 3 to 6 in soy oil is only .13 : 1, whereas in flaxseed oil it is 3.45 : 1; so for all the nutritional reasons why flaxseed oil is good for regular use, soy oil is not.
Tofu usually contains under 10% fat, so the oil type is not a major issue when eating it – unless you have very particular needs.
Soy protein
Soy beans are high in protein: around 38 - 45%.
Soybeans are an excellent source of complete protein. A complete protein contains in the one food all the essential amino acids in a good balance necessary for human health. Meat is well known as a complete protein and concerns have been raised (probably in a way that is highly over rated) that vegetarians may miss out on some amino acids.
So, as confirmed by the US Food and Drug Administration, soy is a good source of protein for vegetarians and vegans. Soy protein has the nutritional equivalent of meat, eggs, and casein for human growth and health.
Tofu – how it is made
Soaked soybeans are ground; water is added and boiled. The pulp is then removed leaving soymilk. Next, a natural mineral coagulant such as calcium sulphate, magnesium chloride, or a mixture of both is added, leading to the soymilk curdling. The curds are removed, placed in cloth-lined forming boxes and varying amounts of pressure applied to form soft, regular, firm or extra firm tofu.
The firmer the tofu, the higher the protein and fat levels.
Silken tofu is made when either calcium sulphate or glucono-delta-lactone is added to a thick, rich soymilk. The mixture is put into a package that is then heated to activate the coagulation and produce the tofu in the package. Typically, tofu contains between 10 and 15% protein and 5 to 9% fat. It is relatively low in carbohydrates and in fiber (as the pulp was removed), making it easy to digest.
Soy production and the environment
Soybeans produce
1. At least twice as much protein per acre compared to most other major vegetables or grains.
2. Five to 10 times more protein per acre than land set aside for grazing animals to make milk.
3. Up to 15 times more protein per acre than land set aside for meat production.
Environmental groups have reported increased soybean cultivation in Brazil has destroyed huge areas of Amazon rainforest. However, most of the soybeans produced in this area are actually grown for livestock fodder and oil production.
Conclusion? There is great environmental merit in eating less meat and more soybeans.
STILL TO COME
The burning question – what impact does soy have on breast cancer? How is breast cancer actually affected by oestrogen? Do the phyto-oestrogens (natural, oestrogen-like substances) in soybeans cause breast cancer, or do they protect from it? Does soy help or hinder in recovering from breast cancer?
Part 2 will be posted Thursday
RELATED BLOG
Eating Well, Being Well
RESOURCES
You Can Conquer Cancer – the revised edition has many other explanations like this one on soy. What type of protein and how much? Which are the best fats to eat and to avoid, and so on. This book is about prevention and long-term good health, as well as cancer recovery.
NOTICEBOARD
Ruth and I leave this week to present our final meditation retreat for the year, Meditation Under the Long White Cloud at Mana retreat centre amidst the peace and beauty of the Coromandel Peninsula in New Zealand.
Then we travel down south to the exquisite landscape at Wanaka to present the 5 day cancer residential program, Mind, Meditation and Healing from November 10 - 14. It will be a delight to be back in New Zealand once more.
Hello Dr. Gawler. I am afraid I am getting very tired of the ignorance of so called educated people to the enormous value of animal production in view of environmental sustainability. I am an organic farmer in conversion and, so far, a successful one and I am going to make a statement.
ReplyDeleteThe success of healthy, large scale organics with the potential to feed a hungry world depends entirely on the availability of huge quantities of animal manures of all types which may be properly composted along with other organic materials (generally in lesser proportions) and added minerals according to the required prescribed needs of particular soil types. Otherwise farming is depended on (as is conventional cropping) huge inputs of artificial and chemical fertilizers and sprays MUCH to the detriment of our world.
Composts are carbon sinks and if all farmers began farming well and orgainically we would not have the climate change concerns not the hideous threat of growing pollution we now suffer in our seas, water courses and soils and the atmosphere.
This never ending persecution of those who farm animals must stop. Western people have eaten meat pretty well as long as they have existed and responsible and caring animal farming is of huge benefit to our soils. It creates a wonderful cycling of nutrients particularly in Australia where they exist where it is and always has been impossible to grow crops of any kind.
Also grass fed (grazed) livestock produce much healthier, nutrient rich meat as opposed to grain and lot fed meat and this is something you should be studying as we have a huge advantage with this in Australia.
I know how difficult it is for people to change their mindsets but at a time when finally the beauty of composting is finally being realized in areas of Australian agriculture, please don't damn it by turning one and all against those growing healthy livestock....and please look at the nutritional value of A2 milk. It is a very different product from what is now produced sin the last few decades where our ever diminishing farmers are being forced to produce more and more milk for less and less return which requires they milk huge non A2 producing Holsteins.
PS: Sorry about the previous grammar and typo's. Really should reread what I have written before publishing!
ReplyDeleteHi Liz, I've just read your response to Dr Gawler's article & found it most interesting. Are you saying there is no organic fertiliser other than that from animals?
DeleteI appreciate your hard work. you have put to write such a wonderful article.
ReplyDeleteorganic soybean meal