Soya is widely used in all kinds of food products. It is highly visible as soya milk, or tofu on our supermarket shelves, but these products remain the province of those on special diets, such as vegans and those who are lactose intolerant. However, soya is also found as an added ingredient in products everyone eats, ranging from bread to burgers. Debate still rages about whether all this soya is good for us or not. Soya is a mainstay of most vegan diets, and as such, many vegans are wedded to it, for better or for worse. But even meat-eaters, who may think soya has nothing to do with them, are consuming ever-increasing amounts of it too, and it’s hard to avoid.
Soya beans are processed in a multitude of different ways to produce a variety of products. The beans can be sprouted or just eaten whole; roasted to snack on; fermented to make tempeh, miso or soy sauce; ground to make flour for baking; extracted to provide oil for cooking or commercial processes, and the emulsifier lecithin; turned into animal feed; squeezed to make soya milk, which in turn may be converted into soya cream, cheese, yoghurt or ice cream; and, perhaps most ubiquitously of all, turned into tofu, which in itself is almost as versatile as the original bean.
Soya is a cheap source of easily digestible protein, which accounts for its main use as an animal feedstuff. This reason has also resulted in its popularity with manufacturers of meat products, leading to the widespread addition of soya protein to burgers, sausages and meat pies. Soya is a cheap way to increase the protein content of these meat products.
Anyone who thought soya was solely the concern of vegetarians should consider the implications of a quick trip to a fast food restaurant. There, you may eat a burger made from animals fed on soya. The burger itself probably contains soya to boost its nutritional content - as may the bun! The chances are it will have been fried in oil derived from soya beans too. Even reaching for that chocolate bar, you will probably be consuming soya lecithin, used as an emulsifier.
So why does this escalation of soya consumption matter? Surely soya beans are, like all vegetables, good for our health? Soya is an excellent source of protein, as it contains all twelve of the amino acids we require for health. It is also cholesterol free, and consumption is thought to actually lower cholesterol levels.
Soya also contains substances called isoflavones, but the health benefits of these are less clearly understood. Isoflavones, which are found in flaxseed and cereals, as well as soya, are plant oestrogens. They are similar in structure to oestrogen found in the human body, and are able to mimic it in some processes. Like most hormones, oestrogen plays a complex role in the body, and is involved in many different processes essential to health. To further complicate matters, isoflavones may have an oestrogen-enhancing, or, anti-oestrogen effect. This is because isoflavones are not identical to oestrogen, but are similar enough that they may replace oestrogen in some reactions in the body. In some cases, this may act to increase the apparent amount of oestrogen in the body, but in other cases, because the isoflavones do not react in exactly the same way, they may effectively prevent oestrogen from completing reactions required in the body.
There has been much conflicting health advice: some indicating that isoflavones are nothing short of a miracle, others suggesting that they may be rather harmful. Some of the reputed health benefits of isoflavones are: preventing certain types of cancer; contributing to the health of the prostate; relieving menopausal symptoms; reducing the risk of heart disease; improving bone density and acting as an anti-ageing potion through anti-oxidant activity. On the other hand, isoflavones may have a detrimental effect on thyroid function, and exacerbate breast cancer. The truth is probably somewhere in between, and depends on individual circumstances. In any case, most of this “advice” is aimed at people taking concentrated isoflavone supplements, and is based on animal tests, which are notoriously unhelpful for predicting effects in humans. However, the quantities of isoflavones found naturally in soya are relatively low, and in Asia, after generations of consumption of soya products, their rates of breast cancer are lower than those in the West. This cannot provide a definitive answer, as there are many other differences, such as environmental and dietary, to be considered.
Soya also attracts much attention for its environmental impact. Vast tracts of land across South America, especially Brazil, are given over to production of soya, at the expense of the lungs of the world – the tropical rainforests. Huge amounts of biodiversity are being lost as farmers try to satiate demand for this monster crop. A decade ago, concern was targeted at the meat industry, as rainforest was cleared to make way for resource-hungry cattle ranches. Now it seems that soya is the culprit. However, the huge majority of soya grown is actually used as a feedstock to rear animals. Much less land is needed to grow soya for people to eat, than is required to raise animals and animal feed, to provide people with a meat-based diet: 1 acre of land will feed up to 100 times more people if used to produce vegetables than if used to rear meat for food. In addition, the intensive rearing of animals has its own direct negative effect on the environment, in terms of huge amounts of waste requiring disposal.
The desire for high yield from soya crops has led to the use of genetically modified strains, in a huge unpredictable experiment, that is still being played out. Associated with this, is the spiralling use of pesticides and fertilisers. These chemicals are suspected to have a serious impact on the health of farmers, their neighbours and the environment.
The benefits of the soya bean as an excellent source of protein remain.
Unfortunately so do the negative effects on the environment, and, as with
most foods, we are a long way from fully understanding all the intricacies
of the effects of this bean on health. Judgement on the production and use
of soya remains in the balance. The magic bean itself is not the problem – the
real concerns arise from the way humans choose to exploit it.
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These pages were last updated 22nd May 2010
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