SOYA AND CANCERS soya and prostrate cancer

History of soya
The soya plant (Glycine max) was cultivated in China before 3000 B.C., and was classified as one of the five sacred crops. The first written record is a 2200 B.C. farming manual advising Chinese farmers how to get the best from their crop. Missionaries brought soya to Europe in the 17th century but climatic and soil conditions were unsatisfactory. Soya was introduced in the USA in the early 19th century (originally arriving as ballast aboard returning clipper ships), but soya farming in the USA only expanded dramatically after World War II, when production in China was devastated.
Cultivation of soya
Soya is a frost-sensitive summer annual, and it takes about 75-80 days for the beans to fully mature; plants may reach 1 metre high. Seeds are borne in hairy pods which grow in clusters of three to five; each pod contains two or three seeds, which resemble peas. When the seeds are mature, the upright vine and foliage begin to shrivel and the leaves fall away. Harvesting by machine must be completed before the pods shatter.
Roundup. and other non-selective herbicides are used extensively for weed control in soya cultivation, but they cannot be applied to weeds within growing crops because they will kill the crop as well as the weeds. Using biotechnology, plants are being developed that are tolerant to Roundup. herbicide; farmers will be thus able to spray soya crops during the growing season.
Soya is now a global staple food and about 110 million tonnes of beans are produced, mainly in the United States (50%+), Brazil (20%), Argentina (10%) and China (8%). Individual farmer's crops are bulked before export. European oil mills process about 15 Mt of soya beans annually, mainly imported from the USA. Soya beans and their products account for 25% of US agricultural exports to the EU and were worth more than $2 bn last year.

Soya as a food ingredient
About two-thirds of all manufactured food products contain derivatives or ingredients made from soya. Before they can be used in food products the soya beans have to be cleansed, cracked, dehulled and rolled into flakes, which ruptures the oil cells for easy extraction. The oil is extracted using a food-grade solvent, n-hexane - mostly for production of vegetable oil and margarine. In its pure form as a vegetable oil, it is often used in salad dressings and mayonnaise; as a vegetable fat it is used for baking and frying. Soya lecithin acts as an emulsifier in some chocolate, breakfast cereals, ice cream, sweets and margarine. Soya oil is also used in a wide variety of non-food products eg soap, biological detergents, plastics, and CFC-free cooling agents; the derivative glycerine is used in the manufacture of emulsifiers for skin cream and softeners for gelatin capsules.
Soya flours were developed in the 1940s by grinding and screening defatted flakes; these are used to increase the shelf-life of many products and improve the colour of pastry crusts; the flour is free of gluten, so cannot replace all the wheat or rye flour in bread-making but can be used at about 15% to give a dense bread with a nutty flavour and moist quality. Texturised soy protein (TSP or TVP) is made from soya flour that is compressed until the fibres change in structure. It is available to home cooks as a dried, granular product and in chunk-sized pieces for rehydrating and use as a meat-replacer.
Following the development of methods to produce isolated soya proteins in the 1950s, it is also processed for use as soya protein in biscuits, sweets, diet drinks, pasta and frozen foods; it also improves the consistency of meat products. It is added to many foods including pizzas, noodles, bread, foods for special dietary needs, for instance soya drinks, which serve as a substitute for cows milk. Various cheese and other milk and meat substitute products, such as miso, tofu and tempeh, can be made by fermenting soya protein. In addition, naturally-brewed soya sauce uses a starter culture called koji, a member of the Aspergillus family, with a mixture of soya beans and wheat.

Soya in nutrition
Soya bean protein quality is comparable to meat and eggs. The vegetable oil is poly-unsaturated, has a low level of saturated fatty acids and is free from cholesterol, but contains both essential fatty acids - linoleic and linolenic. Soya beans and the foods made from them are also rich in iron, B vitamins, calcium and zinc. Soya protein is said to have the effect of reducing cholesterol levels in hypercholesteroaemic people (Anderson, 1995). The Food and Drug Administration (FDA) is proposing to authorise the use of a health claim for foods which contain soy protein which will allow them to state that they can reduce the risk of heart disease. The action comes in response to a petition filed by Protein Technologies Inc (PTI), a leading supplier of soy proteins and a unit of DuPont. If such as claim is allowed soy will join oats as a food allowed to claim on packaging and labels that it "may reduce the risk of heart disease, as part of a diet low in saturated fat and cholesterol". Foods that would be able to carry the claim include soy milk, vegetable burgers and tofu (New Nutrition Business, 4(3), 1999).

Soya and phytoestrogens
Soya is an important source of a group of non-nutrients known as the phytoestrogens; compounds with structural and functional similarities to the natural oestrogenic hormones present in the body. Examples are daidzein and genistein, present at levels around 3mg/100g wet weight in raw beans. In certain situations these chemicals can behave like a very weak form of oestrogen.
Epidemiological studies (primarily from Japan, where soya consumption is high) suggest a beneficial, protective effect for the phytoestrogens against certain sex hormone-dependent cancers - including breast and prostate cancers. Phytoestrogens present in a wide range of food plants (including soya) may have deleterious effects on reproductive efficiency when consumed by animals; there is no evidence for a parallel effect in man. Work is under way which will give a better understanding of how the phytoestrogens in soya behave in humans, since these actions are complex and not completely understood.
Babies may be given soya-based formula milks for one of the following reasons: (1) a small number of babies cannot tolerate cows' milk; (2) some parents choose for themselves to feed their baby soya-based formulae because they have a family history of allergy or for other reasons; (3) soya-based formulae are made entirely from plants and this makes them acceptable to vegans and other groups who do not want to use feeds based on cows' milk. At present there is no evidence that phytoestrogens in soya-based formulae cause any problems.
The UK's Chief Medical Officer recommends that 'if your baby is under one year of age and your doctor has recommended that you feed your baby with a soya-based infant formula, you should continue to do so. If your baby is over one year of age, you should ask your doctor or health care professional about introducing your baby to cows' milk as babies can outgrow allergies. If you are using a soya-based formula, but not on the advice of your doctor or another health care professional, talk to your doctor or other health care professional about whether to continue using it or whether to switch to another type of feed'.

Genetically-engineered soya - the technology
Monsanto, the US-based multinational speciality chemical and pharmaceutical company, has developed a new soya bean plant which is genetically-engineered to be resistant to the Monsanto herbicide, Roundup.. In traditional soya varieties, Roundup. blocks the build-up of essential substances for growth of the soya plant, but the modified plant, Roundup ReadyTM produces a new type of protein enabling it to circumvent this blocker. One of the claimed advantages of using Roundup ReadyTM soya beans is that weeds can be controlled after the young beans have started to grow, with just one herbicide. Monsanto estimate that around one third less herbicide overall can be used with this variety compared with conventional crops.
Monsanto say that genetically-modified (GM) soya is indistinguishable from conventional beans in composition, nutrition and processing characteristics; a US company Genetic ID claims to have a test available that can detect the genetic alteration, but this method will only work prior to processing. The new protein is not found in soya oil or lecithin and it is claimed that protein traces in soya meal are inactivated during processing. People who are allergic to conventional soya products will also be allergic to the genetically-modified soya products.

Genetically-engineered soya - regulation
Oversight of this technology and other genetic modification techniques is provided by the US Department of Agriculture, the Food & Drug Administration and the Environmental Protection Agency. FDA ensures the safety of foods developed by genetic engineering through science-based risk evaluations. This requires developers of foods from modified plants to address whether known allergens have been transferred to the modified product; to demonstrate that the new food does not contain increased levels of previously-known toxic substances or new hazardous substances; and that the nutritional value of the product has not been compromised.
The final US approval for use of Roundup. herbicide with herbicide-tolerant soya beans was granted in Spring 1995 by the US Environmental Protection Agency. The EU authorities issued an import licence according to EC directive 90/220 (product release directive) in Spring 1996 - although this approval is restricted to import and processing. It is also approved as safe by Japan, Argentina and Mexico.

Genetically-engineered soya - production, processing and labelling
The 1996 USA crop of 64 million tonnes contained about 2% of GM soya beans. The 1997 crop contained approximately 15% GM beans. Monsanto says that segregating beans for mass markets would be economically and physically impractical for farmers, grain companies and shippers. The arrival of deliveries of mixed GM and traditional soya beans in Europe (9Mt out of a total European market of 13-14Mt) has resulted in widespread discussion over the safety and labelling of genetically-engineered ingredients in foods.
The UK's Advisory Committee on Novel Foods and Processes stated in 1994 that "the Roundup ReadyTM soya beans ...and products derived from these beans are equivalent to and as safe for human consumption as beans from conventional soya bean strains and products derived from them." At a UK press conference in August 1996, ACNFP Chairman Professor Derek Burke said:- "The beans are processed by a severe extraction procedures that destroy the plants' genetic material and also destroy the bacterial enzyme introduced to make it resistant... In the products there is no bacterial DNA or bacterial enzyme. Flour from the new soya is analytically indistinguishable from the traditional soya."
The USA's Institute of Food Technologists comments that 'food labels have been established to provide "material information" about a product, such as ingredients and nutrition information, or warnings about a health risk. Since genetically-modified foods do not pose any new or unique risks, such labels would not provide health or safety information and could mislead by implying that there is a risk'.
Commodity crops such as soya are traded on the international markets in huge amounts. Segregating of commodity crops requires separate production and handling facilities at every stage of the supply chain. The UK bread-baking industry has bought some supplies of 'identity-preserved' conventional soya from Canada, and the frozen-food supermarket chain Iceland is among many UK retailers avoiding the use of genetically-modified soya in their own-label products.
Agreement has been reached on an EC Regulation (1139/98) on the labelling of (GM) soya and maize (MAFF Food Safety Information Bulletin, July 98). This requires all food products containing GM soya ingredients to be clearly labelled. Declarations will appear in either the ingredients listing, for example, in relation to soya ingredients as follows: soya flour (produced from genetically modified soya); or soya (genetically modified) flour; or soya* flour; then as a footnote, which may be no smaller than the list of ingredients: * genetically modified; or * produced from genetically modified soya. In the case of products where there is no ingredients list, the words 'produced from genetically modified soya' must appear on the product label.
The Regulation came into effect on 1 September 1998. It will not however apply to products manufactured and labelled prior to the Regulation coming into force, nor to products in which neither novel protein nor DNA is present. The Regulation also contained a six month transition period for products where other forms of wording have been used to indicate the presence of GM material.
The UK Consumers' Association commented in the March 1999 edition of 'Which?' magazine that "any food ingredients containing GM material (protein or DNA) from soya are labelled. But where protein or DNA from the GM source is removed in the processing, the regulations consider that these ingredients are equivalent to conventional ones, and so don't have to be labelled. For example, some oils produced from GM soya, contain no detectable protein or DNA in the finished product.
Additives produced using GM technology are also exempt from GM labelling, although this is currently being reviewed and may change in the future. Currently, there is no list of agreed European ingredients that don't need labelling so it is up to the manufacturer to decide which ingredients are exempt. Outside Europe, the international agreements on labelling are still being debated."
Pressure group and public attitudes to genetic engineering in the food chain
Some pressure groups oppose all forms of genetic engineering, but others are either focusing on particular aspects of the technology in plants, or animals, or on environmental concerns. Some prioritise the issue of consumer choice - demanding the labelling of foods containing GM ingredients.
Providing effective communication about the benefits and risks of new technologies depends on understanding the underlying concerns of the public as well as the more technical issues. The public's perception of the risks of genetic engineering is mediated by their recognition of the tangible benefits of specific products of the technology, for example genetically engineered products with health- or environment-related benefits.
If information about genetic engineering in the food chain is perceived by the public as coming from a source that they do not trust, or promoting a particular vested interest, there is a danger that this could result in an unnecessarily negative perception of the technology by consumers. It is also useful to address some of the wider social issues (for example, worries about ethics) in the information provided, as these might also be driving consumer reactions (see publications by Dr Lynn Frewer and colleagues for further information).
Consumers around Europe have recently been questioned on their attitudes to GM foods. Across Europe, in a 5000-person MORI/Greenpeace poll, 59% were opposed to its development and 22% supported it, with the French and Danish coming out most strongly against. The British showed some of the most positive attitudes with only 51% opposing development. A separate survey in Germany found that 95% of consumers wanted mandatory labelling of these foods.
Some publications in the literature
Anderson, J. W., Johnson, B. M. & Cook-Newell, M. E. (1995) Meta-analysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine 333 276-
Burks, A. W. & Fuchs, R. L. (1995) Assessment of endogenous allergens in glyphosate-tolerant and commercial soybean varieties. Journal of Allergy & Clinical Immunology 96 1008-
Butler, D. (1996) Europe agrees a compromise on food labels. Nature 384 502-3
Frewer, L. J., Howard, C. & Shepherd, R. (1996) Effective communication about genetic engineering and food. British Food Journal 98 (4/5) 48-51
Frewer, L. J., Howard, C. & Shepherd, R. (1996) The influence of realistic product exposure on attitudes towards genetic engineering of foodstuffs. Food Quality & Preference 7 (1) 61-67
Frewer, L. J. & Shepherd, R. (1995) Ethical concerns and risk perceptions associated with different applications of genetic engineering: Interrelationships with the perceived need for regulation of the technology. Agriculture & Human Values 12 (1) Winter 48 -57
Tuley, L. (1996) Healthy outlook for soya proteins. IFI no 5 24/5 and 27/8
Items from Nature magazine
Distrust in genetically altered foods - editorial (1996). Nature 383 559
Genetic resistance spreads to consumers - news (1996). Nature 383 564
Trade war looms over gene-altered foods - news. (1996). Nature 384 301
Pros and cons of foreign genes in crops - correspondence (1997) Nature 385 290
Further information from:-
Advisory Committee on Novel Foods & Processes, Ergon House c/o Nobel House, 17 Smith Square, London SW1P 3JR tel. 020 7238 3000 (report on herbicide-tolerant soya beans in 1994 Annual Report)
Biotechnology & Biological Sciences Research Council PR Dept., Polaris House, North Star Ave, Swindon SN2 1UH tel 01793 413200 (including the booklet 'Ethics, Morality and Crop Biotechnology' by Roger Straughan and Michael Reiss)
Biotechnology in our Food Chain - website developed to provide a public information service on some of the key issues of interest to the public; explores the potential opportunities and risks associated with food-related biotechnology (
European Federation of Biotechnology tel +31 70 3653857 (biotechnology handbook and leaflets)
Food Advisory Committee, Ergon House c/o Nobel House, 17 Smith Square, London SW1P 3JR tel. 020 7238 3000 (including Q/A on GM soya beans attached to press release issued as FAC15/96)
Food & Drink Federation, 6 Catherine St, London WC2B 5JJ tel. 020 7836 2460 (for a copy of booklets in the 'Food for our Future - a guide to modern biotechnology' series); web site address:
Genetic ID, 500 North Third St Suite 208, Fairfield Iowa, 52556, USA
Genetics Forum, 94 White Lion St, London N1 9PF tel. 020 7837 9229 (for booklets including 'Spilling the Genes - what we should know about genetically-engineered foods')
Green Alliance tel 020 7836 0341 (for copy of 'Why are environmental groups concerned about release of genetically modified organisms into the environment?' and other briefing documents); web site address:
Greenpeace, Canonbury Villas, London N1 2PN tel 020 7865 8100 (for a handout entitled 'Health and Environmental Risks of Genetically Modified Soya' and other briefing information)
Institute of Food Technologists - 221 N LaSalle St, Suite 300, Chicago Il 60601-1291, USA; tel 001 312 782 8424 and world wide web site at
Institute of Grocery Distribution, Grange Lane, Letchmore Heath, Watford WD2 8DQ tel. 01923 857141 (for lists of soya bean growers and distributors offering supplies of non GM soya) and for other information on soya (use the 'search' facility on the site)
Monsanto Europe S.A./N.V., Avenue de Tervuren 270-272, Tervurenlaan 270-272 Letter Box No 1, B-1150 Brussels tel 00 32 2 776 41 11 (for information packs including 'Plant Biotechnology - harvesting solutions for tomorrow's world' - produced jointly with the American Dietetic Association)
National Centre for Biotechnology Education tel 0118 987 3743 and web site (for resources for biotechnology education)
National Farmers Union, 164 Shaftesbury Avenue, London WC2H 8HL tel. 020 7331 7200 (for information about their Biotechnology Working Party)
National Food Alliance, 5-11 Worship St, London EC2A 2BH tel. 020 7628 2442
The American Soybean Association, Rue du Commerce 20-22 bte 4 1040 Brussels - Belgium
The Food Commission (UK) Ltd, 3rd Floor, 5/11 Worship St, London EC2A 2BH tel. 020 7628 7774
The Soya Bean Information Centre, 59 Russell Square, London WC1B 4HJ tel. 0345 023288 (for handouts on soya and access to a 'Careline' operated by Monsanto)
Compiled and Issued by:
IFR Communications
Institute of Food Research,
Norwich Research Park
Colney, Norwich NR4 7UA, UK

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