Soya -- Is It Part Of A Healthy Diet

When people talk about soya these days they usually focus on how it is produced – whether it is GM (genetically modified) or not. The biggest problem with it, however, is that it is another common food, like wheat and corn, that finds its way into a very large number of foods. It is cheap, and it is very high in protein, so food manufacturers find it very useful as an enricher and a life-extender.

Soy sauce. soy flakes, soya flour, soya bran, soya oil and soya milk are easy to spot as soya products. Tofu, miso and tempeh are also made from soya. However, soya is often an unnoticed ingredient in shop-bought bakery items such as breads, rolls, cakes, pastries, doughnuts, biscuits / cookies and other products including:

Soya can be disguised on food labels in many different ways: as hydrolysed vegetable protein, soy protein isolate, protein concentrate, textured vegetable protein (TVP), vegetable oil, plant sterols, or as the emulsifier lecithin.

Soya is also used extensively in agricultural feeds for intensive chicken, beef, dairy, pig and fish farming. Therefore we are very likely to be eating it indirectly whenever we eat eggs, milk, meat or fish.

So, unless we're actively avoiding it, or eating an all-natural diet, we'll probably be eating soya most days.

Well, is it a problem? Isn't soya supposed to be healthful, and in fact even encouraged for certain medical conditions?

It had been known since the early 1980s that phyto-oestrogens (plant oestrogens) such as the isoflavones in soya could produce biological effects in humans. Many health claims were made for soya on account of the isoflavones it contained, such as easing menopausal symptoms, improving bone density and protecting against certain hormone-related cancers. The rationale for the claims was that rates of these cancers, osteoporosis and menopausal problems were lower in east Asian populations, who, it was claimed, had historically eaten diets rich in soya.

However, in 2002, the British Government's expert committee on the toxicity of food (CoT) published the results of its inquiry into the safety of plant oestrogens, mainly from soya proteins, in modern food. It concluded that in there was no clear evidence supporting many of the claims made for it as a health food.

The committee pointed out that the Asian diet was not in actual fact high in phyto-oestrogens. Asians historically did not consume that much soya, and the little they did eat had usually been fermented for months. They did not consume unfermented forms such as soya milk, soya burgers or foods made with soya flour. This fact is critical, as the way soya is processed affects the levels of phyto-oestrogens. Traditional fermentation methods reduce the levels of oestrogenic isoflavones by a factor of two or three. Modern factory processes do not. Furthermore, modern strains of soya used in the West have significantly higher levels of isoflavones than Asian ones because they have been bred to be more resistant to pests (the higher levels of isoflavones make them infertile).

Toxicologist Dr Mike Fitzpatrick, who was instrumental in getting governments to start investigating the health issues surrounding soya, calculated that babies fed exclusively on soya formula could receive the oestrogenic equivalent, based on body weight, of five birth control pills a day.

Indeed, a Royal Society report on Endocrine Disrupting Chemicals in 2000 had already concluded that soya milk should not be recommended for babies and young children even when they had cow's milk allergies, except on medical advice, because of the high levels of oestrogenic isoflavones it contained. The report had also observed that mass exposure to soya isoflavones had only occurred in the past thirty years. Soya had not been part of the general food supply in the West until the 1970s, when incorporation of soya protein into processed foods became widespread.

The current advice of the UK's Food Standards Agency is that soya's potential to have an adverse effect on babies' hormonal development is still controversial, but that soya formula should only be given to infants under 12 months old in exceptional circumstances. Soya milk for babies has always been confined to a small minority in the UK. However, the situation is different in the US, where thirty to forty per cent of all infants are raised on soya formula -- not least because it is given away in welfare programs.

There are also concerns that a high intake of phyto-oestrogens from soya can disrupt the function of the thyroid gland. This is a potential major public health concern, since the incidence of hypothyroidism (underactive thyroid) is increasing in Western populations and has been found to affect many more people than had been previously been thought. Experts now believe that hypothyroidism is seriously underdiagnosed. Untreated, it can lead to obesity, heart disease and many other chronic health problems.

Further issues surrounding soya relate to the essential fatty acids omega-3 and omega-6. The importance to our health of having the correct balance of these fats is now becoming recognized. Unfortunately, most of us take in too many omega-6s and too few omega-3s. The oil produced from soya is high in the omega-6s. As it is used extensively in the manufacture of snack foods such as crisps or chips, confectionery, deep-fried take-aways, ready meals, ice-creams, mayonnaise and margarines, it is thought to be one of the reasons our balance of omega-3s to omega-6s is so out of kilter.

To conclude, there appear to be serious questions over whether soya in the form in which we generally eat it in the West is safe, let alone a 'health food'. Before we let it become a major constituent of our diets, perhaps we should remember the following:

More information on the concepts outlined in this article can be found in the e-book Why Can't I Lose Weight -- The Real Reason Diets Fail And What To Do About It at