FEATURE It is also necessary to analyse the accuracy of the claims being made, since the fact that most such reports have been based on the opinions of a few individuals means that the information - currently being put forward as fact - may be biased and flawed. For example, Sally Fallon and Mary Enig have suggested that eating soya foods dampens libido and makes people look older, and that feeding children on soya infant formula could influence their sexual orientation <5) (a statement that was later removed from further re-prints of similar articles). Not only are these claims subjective and completely unsubstantiated, but they also serve to create hysteria and anxiety amongst those who have quite happily been eating soya over the years. One of the main scientific findings cited was from a study on Japanese Americans living in Hawaii, which indicated that those participants who ate the most tofu in their mid-life had the greatest decline in brain function and incidence of Alzheimer's disease and dementia when they where elderly. However, the original study also pointed out that the men who ate the most tofu were also more likely to have spent their childhood in poverty in Japan, and that this nutritionally deprived childhood may have been more responsible for their accelerated brain ageing than their tofu intake! 12 ). J Another statement made was that "almost no phytoestrogens have been detected in dairybased infant formulae or in human milk". This is hardly surprising since phytoestrogens are plant compounds that are found in products derived from plants. However, what this and other articles fail to mention is that cow's milk itself is loaded with highly active mammalian oestrogens that are likely to exert far greater effects than weaker plant oestrogens <13>. In addition, many of the effects on unborn children attributed to soya are not in fact based on the results of studies on phytoestrogens, but relate to the effects of a synthetic oestrogen - diethylstilbestrol (DES) - which was prescribed to women with low oestrogen from 1948-71. This drug caused some of the male children born to these women to have small testes and malformed penises and so it has been assumed that other oestrogen-like substances could have similar effects - despite there being little evidence to support this. It is also interesting to note that much of the original research on phytoestrogens was commissioned by two aviculturists from New Zealand, who were concerned about the side-effects of eating soya on their pet parrots - and often claims about the potential effects of soya-formula on infants have just been extrapolated from this research. ( J This article is not trying to suggest that soya is completely safe and so should be eaten ail day and every day, but as with any food, it has both benefits and potential side-effects. For example, if we ate too many carrots we could get carotenosis (vitamin A poisoning) and turn yellow, but that does not mean to say that carrots should be excluded from the diet. The problem comes when trying to determine what is a safe amount to eat - when the benefits will outweigh the dangers. sumption of soya may also not be that likely to result in thyroid disorders, since one of the main studies on which this claim was based required the test subjects to eat 30g of pickled roasted soya beans per day for 3 months ! 18 ), something which is hardly common in the Western diet. ^ In Japan soya foods have been eaten for hundreds of years, and although the studies quoted in The Observer found that the average amount eaten in Japan was only 8g per day, this was probably a mean value derived from a sample where some people ate far more soya and many ate none at all, as is the growing trend in the more Westernised cities. In contrast, a study carried out in a village in rural Japan, where the traditional diet is still eaten, found that residents ate around 75g of soya bean products a day, including tofu, miso, fermented soya beans and boiled soya beans <14>. Other studies have also shown that oriental adults eat around 5560g of soya protein daily, equivalent to 2 servings per day, and in fact, the consumption of this amount of soya was also linked to the lowest breast cancer risk in females. The arguments against soya foods have often been aimed at producers in the USA where the big businesses involved have begun touting soya as a so-called 'miracle cure'. I can therefore well understand why it is necessary to look into these claims, since many of them may be as misleading as those being made in the articles discussed here. However, when it comes to vegans in the UK, their consumption of soya is generally not due to being barraged with advertising and marketing hype, but rather that soya foods are generally tasty and animalfree. In the end, although it is of course essential to understand the nutritional aspects of our food, the practice of regarding every food as a collection of chemical constituents should not necessarily be the overriding factor that affects our decisions about what w e eat. O When it comes to the negative components in soya, such as haemagglutinin, trypsin inhibitors and phytates, it should be pointed out that these are present in many legumes and seeds, and are not just found in soya beans. For example, haemagglutinin is one of the toxic compounds found in red kidney beans, but it is actually destroyed by traditional or industrial cooking methods so should not generally pose a problem to human health. Trypsin inhibitors, which are present in many foodstuffs including eggs, cereals and tuberous legumes, are also mainly destroyed during cooking and it is thought that any negative impact they could have on protein digestion would be insignificant because of the high protein intake in most Western diets. Also, at the levels consumed by humans, protease inhibitors are very unlikely to cause any of the adverse effects on the pancreas that have been observed in animals!15). Meanwhile phytates are abundant in all foods that are high in fibre, and soya may not have "a higher phytate content than any other grain or legume that has been studied"!16) - as was claimed in one article whose source of information was actually a study carried out on legumes in the Sudan. Other evidence seems to indicate that lima beans, peanuts and wild rice all have higher levels <17). In addition, all of these toxins are destroyed during the fermentation process, so are absent in foods such as tempeh or miso, and their levels are greatly reduced in the precipitation process that is used to make tofu. Soya foods also supposedly contain high levels of aluminium, which is toxic to the nervous system and the kidneys. However, research shows that most soya products contain such low levels of aluminium that they are difficult to detect and the levels of aluminium found in soya milk may have been exaggerated due to contamination during analysis. Finally, the con- It cannot be denied that soya has many health benefits because it is high in fibre, a good source of protein and low in fat. There is also a large body of evidence to support the view that it could help to prevent certain cancers and other chronic diseases. Soya has been eaten throughout history in many Asian countries and there seems to be little evidence in these areas of the supposed detrimental effects on health from eating soya foods. Soya can form an important part of a varied vegan diet, both in the form of traditional soya food such as tofu and tempeh, and also soya products such as milk, cheese or yoghurt substitutes. These can also be used to make interesting and delicious vegan dishes, and so there is no reason why they should be excluded from the diet - especially on the basis of limited scientific evidence about the potential effects of excessive intakes of some of the components of uncooked soya beans. Finally it has to be said that a vegan diet, whether it is rich in soya or not, will always be preferable to one based on milk and meat for a multitude of reasons - nutritional, ethical and ecological. REFERENCES: 0> Messina & Messina (1994), <2> Dwyer et al (1994), <3> The Vegan Society Soya Information Sheet, <*> Huck (1998) Health Supplement Retailer, <5> Fallon & Enig (2000) Nexus Magazine - April-May, <6> Baten et al (1989), PI McClenaghan (1999) The Nutrition Practioner - October, <*> The Vegan Society Soya Information Sheet, <*> Kurechietal (1989). <"Âť Phillimore (2000) The Observer Magazine - 27 August, <' '> British Nutrition Foundation (2000) www.bnf.co.uk tiz) www.NutritionNewsFocus.com 19 April 2000, l'3> Klaper as quoted in the Phytoestrogens Information Sheet, f'4> The Vegan Society Phytoestrogens Information Sheet, <15> McClenaghan 1999, <16> Hattersley (1997) Nexus Magazine Vol.4 No.3,(17' Messina & Messina (1994), <Âť> Nippon Naibunpi Gakkai Zasshi (1991). The Vegan. Autumn 2000 13