All soys are not the same
by Luke Rickards

In health food land, the soya bean is considered king. From a nutritionist’s point of view, it’s the most concentrated plant protein available with all eight essential amino-acids, in ratios close to ideal for human needs. It’s high in all the vitamins, minerals and essential fatty acids so necessary for the malnourished. It has no cholesterol, is high in fibre and low in calories and saturated fats, making it the dieter’s dream. Soya beans contain phytoestrogens (isoflavones) said to prevent cancer, lower cholesterol, reverse osteoporosis and ease menopausal symptoms. And to put the icing on the cake, it’s versatile enough for even the most creative chef and you don’t have to kill anything to eat it.

Yet the elevation of soy to superfood may well be premature. Recent clinical observations suggest that while some soy foods offer distinct benefits, others pose significant risks, particularly when eaten in large amounts.

The modern marketing geniuses have managed to convince us that the traditional diet throughout Asia was based on soy foods. In reality though, the soya plant was used mainly in crop rotation, to fix nitrogen into the soil after staple food crops like rice, wheat, millet or barley had been harvested. The beans were considered unfit to eat and were used only by the poor in times of extreme food shortage.

This was because they found the beans nearly impossible to digest properly. Modern science has discovered that this is due to the unusually high levels of 'trypsin inhibitors’ present in soya beans. Trypsin inhibitors block the action of trypsin, a digestive enzyme secreted by the pancreas, which is necessary for the break down of dietary proteins into smaller units called amino acids, which can then be absorbed by the body. So although the actual protein content of soy foods is quite high, if a large portion of it isn’t being digested, its benefit may only be minimal. A secondary consequence is that when proteins aren’t effectively broken down by digestive juices before they pass from the body, they tend to putrify in the bowels causing the formation of harmful toxins and gas. High levels of trypsin inhibitors within the diet have also been associated with more serious digestive disorders, including pancreatic cancer.

The soya bean did not serve as a food in Asia until the discovery of fermentation in the late Chan dynasty (around 240 BC). The first soy foods were fermented products like tempeh, miso, natto, soy sauce and tamari. During the fermentation process specialised bacteria and molds not only eliminate the trypsin-inhibiting effect but also predigest the beans making them much easier to assimilate. Even then, these products were mainly used in small amounts or as condiments. The most liberal use of soy foods was by celibate vegetarian monks who found that tofu and soy milk were helpful because they dampened libido. The problems associated with trypsin inhibitors are more commonly observed with unfermented soy foods such as tofu, soy milk (as most people who have ever drunk a large amount can testify), soy flour products, soy protein isolate (SPI) and textured vegetable protein (TVP).

Another disadvantage of soy foods is their very high levels phytic acids (or phytates). These are compounds found in the bran or hulls of seeds, nuts, grains and beans. They bind essential minerals such as calcium, iron, manganese, copper and especially zinc in the digestive tract and prevent them being absorbed into the body. As well as the high levels, the phytates in soya beans seem to be so strong that many survive the usual phytate-reducing methods such as long, slow cooking. The soaking and fermenting process used to make tempeh, miso, natto, tamari and soy yogurt significantly reduce the phytate content of soya beans. But what about unfermented products like soy milk, tofu, soy flour, SPI and TVP? Sally Fallon, editor of the Price-Pottenger Nutrition Foundation Journal suggests that just 12 grams per day of these unfermented soy foods can contain enough phytates to lead to a shortage of essential minerals.

The phytoestrogens (isoflavones) found in soy have also come under scrutiny recently. A few years ago these plant oestrogens were credited with promising relief from menopausal symptoms among other benefits, as they mimic the natural oestrogens in the body. However, it’s believed these same isoflavones may cause disruption in the endocrine (hormone) system of healthy people, affecting particularly the thyroid gland, which is responsible for controlling metabolism. Although extra oestrogen may be helpful in controlling certain symptoms of menopause, what is its effect on males, non-menopausal females and babies?

In 1991, the James family, bird breeders in New Zealand, purchased a new soy-based feed for their birds. They soon noticed that they had male crimson rosellas, which usually acquire a red plumage at 18 to 24 months, already brightly coloured at just 11 weeks old. In the ensuing years they had birds with decreased fertility, precocious maturation, beak and bone deformities, immune system disorders, pathological behaviour and goiter and thyroid problems. Autopsies revealed digestive organs in a state of disintegration.

Many of these problems correspond with those observed in infants fed with soy-based formulas. Studies conducted in the US over ten years ago associated soy-based infant formulas with thyroid problems, such as hypothyroidism in babies. Recent reports of other health problems connected with children fed a soy-based formula include immune system disorders, infertility, emotional upsets, premature puberty in girls, learning disabilities in males and irritable bowel syndrome. This isn’t surprising considering that a baby fed with a soy-based formula receives the oestrogenic equivalent, based on weight, of at least five birth control pills per day! It’s no wonder soy milk was not a traditional food for babies in Asia.

As for those modern, sophisticated soy products, soy protein isolate (SPI) and textured vegetable protein (TVP), witness how they’re manufactured. A slurry of soya beans is first mixed with an alkaline solution to remove the fibre. It’s then precipitated using an acid wash (which also leaches high levels of aluminium into the precipitate) and finally, is neutralised in an alkaline solution. The resulting curds are then spray-dried at high temperatures to produce a high protein powder, SPI. The final indignity is a high-temperature, high-pressure extrusion processing of SPI to produce TVP. Carcinogenic toxins, namely nitrates and lysinoalamine, are also formed during these processes.

Both SPI and TVP are highly denatured substances in which several of the protein molecules are rendered largely ineffective. That’s why animals fed with soy feed need lysine supplements for normal growth. In feeding experiments on animals, the use of SPI increased requirements for vitamins E, K, D, and B12 and created deficiencies of calcium, magnesium, manganese, copper, iron and zinc. With the addition of flavourings, preservatives, sweeteners, emulsifiers and synthetic nutrients, manufacturers have managed to turn something that was originally used as a binder in cardboard boxes into a New Age food miracle. Along with soy flour and soy compound, SPI and TVP can be found in breakfast cereals, breads, baked goods, biscuits, gluten-free foods and flours, convenience foods, snack bars, sweets, soy ice-cream, supermarket soy milks, soy chips and crisps, soy cheese, meat substitutes (soy sausages, vege burger patties, not-chicken etc), processed meats (sausages, salami, nuggets and fish fingers), smoothy mixes, body building products, infant formulas, dairy yogurt, pet foods and who knows where else.

What does this leave us with? Well as usual, it seems that ancient wisdom prevails. Choose the traditional, fermented soy foods such as tempeh, miso, natto and tamari. Conveniently, these also happen to be the tastiest, most nutritious and most natural of all the soy products. A small amount of tofu is fine on occasion, if you have a strong digestion, and is improved when prepared or cooked with mineral-rich foods such as the various seaweeds. Tempeh is a better choice for vegans and vegetarians alike as it has double the protein content of tofu, provides greater nutrition and is easier to digest. Rice, oat and almond milk are excellent alternatives to soy milk and often don’t need the addition of sweeteners to make them palatable.

So enjoy your soy, but choose wisely and remember it’s not a staple food. And don’t forget to read those labels.

First printed in the Alfalfa House Co-op Newletter March 2001. Luke is a co-op member and has a diploma in Traditional Chinese Medicine and a degree in Osteopathy.

SOURCES
Natural Health magazine, Mar. 1999 Sally Osborne
Nexus vol 7. no 3 Sally Fallon
Dictionary of Natural Health, N. and S. Drury
www.soyonlineservice.co.nz/

OTHER READING
www.healingdaily.com/detoxification-diet/soy.htmwww.ecologycenter.org/terrain/article.php?id=13578
www.ecologycenter.org/terrain/article.php?id=13579
http://news.bbc.co.uk/1/hi/talking_point/7490202.stm

FAQs
with Kaayla Daniel

Q. People in Asia have been eating soy for 10,000 years. So how could there possibly be a problem?

A. Soy has been a food in China for a little more than 2000 years. Farmers grew soybean plants only as "green manure" – as a cover crop plowed under to enrich the soil. Soy was a fertiliser, not a food. The Chinese originally developed the technique for making soybean paste (best known by the Japanese term 'miso') to preserve protein-rich animal foods. This process was first applied to soybeans and grains in the second century BC at the earliest and appeared in Japan around 500 AD. Legend holds that tofu was invented in China in 164 BC and came to Japan in the eighth century AD. Natto entered the food supply around 1000AD and tempeh no earlier than the 1600s.

Q. I attend lots of vegetarian potlucks. I buy very few soy products myself but still like to spend time with my vegetarian friends. How much soy is safe for me to eat?

A. If you are healthy, go ahead and enjoy the occasional vegetarian potluck. If possible, stick to old-fashioned soy products (miso, tempeh, natto, shoyu, tamari) and eat them at the levels traditionally consumed in Asia. The Japanese eat the most but still average just a few tablespoons. On a weekly basis, a few cups of miso soup, a small serving of tempeh or natto and the modest use of shoyu or tamari in cooking should not be a problem. A little tofu (such as three little cubes you'd typically find in your miso soup at a Japanese restaurant would also be okay. I wouldn't even worry about the occasional ingestion of Tofurky, Veat, Boca burger or other of the highly processed, high tech modern American soy foods. The important thing is don't "pig out."When you join your friends, be a vege-tarian not a soya-tarian.

Q. I've been drinking a soy protein shake every morning for breakfast. I have not increased the number of calories in my diet yet seem to be gaining weight. The only change in my diet is the soy yet I'm being told that soy helps you lose weight.

A. Traditionally, the Chinese only ate products made from whole soy beans. When the bean was split into oil and protein, the oil was used to fuel kerosene-type lamps and the soy protein was used as a fertiliser. It was only used for animal feed when the goal was to "fatten" the animals. Some brands of soy protein contain high levels of isoflavones. It only took 35mg of isoflavones a day in a clinical trial to cause hypothyroidism low thyroid function in healthy Japanese men and women. This is likely to result in a loss of energy and weight gain, as well as other possible symptoms such as hair loss and depression.

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